ORTHOPEDIC MCQS ONLINE OB PATHOLOGY 1A 

A 13-year-old boy is diagnosed with osteosarcoma of his distal femur. The treating surgeon samples the bone marrow from the resection margin of the femur during definitive limb salvage surgery and finds microscopic evidence of tumor. Assuming no change in the resection level, what type of resection would this be considered?

 

 

CORRECT ANSWER:1

 

Based on the Enneking classification of tumor resections, this would be classified as a intra-lesional resection as there are residual tumor cells in the resection margin of the femur. Intra-lesional resections occur in the lesion, as in this case, and are not appropriate for malignant sarcomas. For osteosarcomas, it is common to "sample" the marrow margin at the level of the bone cut during resection.

 

The referenced article by Enneking is the original description of resection margins used in soft tissue sarcomas. Because this referenced article was published when the surgical treatment for soft tissue sarcomas didn't include adjuvant therapy, the results aren't as applicable today. Today with adjuvant therapy, many sarcomas which are close to neurovascular structures can be safely resected without sacrifice of these critical structures.

 

Wrong Answers:

Answer 2: The Enneking classification does not use the term inter-lesional. Answer 3: Wide resections are those where the tumor compartment is maintained but a "cuff" of normal tissue surrounds the resected specimen. If you think of the tumor as the fruit of an orange, a wide resection takes a normal cuff of tissue (the rind) around the tumor in 360 degrees (Illustration A).

Answer 4: Marginal resections are those which occur through the periphery of the tumor in the zone of the pseudocapsule where tumor cells can be located.

Answer 5: Radical resections are those in which the entire "compartment " of the tumor is removed. In the case of Illustration A, a radical resection would require removal of the entire femur as that is the "compartment".

 

 

 

 

 

1. Intra-lesional

2. Inter-lesional

3. Wide

4. Marginal

5. Radical

A 14-year-old child presents to your office with 6 months of worsening knee pain. Figures A through D show the respective radiographs, bone scan, MRI, and histology. What treatment protocol has been shown to maximize survival in patients with this diagnosis?

 

 

 

 

 

 

 

 

 

CORRECT ANSWER:2

 

The history, images, and histology all suggest a high grade osteosarcoma. The appropriate treatment includes neoadjuvant chemotherapy, surgical excision, and adjuvant chemotherapy. The difference between neoadjuvant and adjuvant therapy is their relationship to the surgical excision. You could, for example in high grade soft tissue sarcomas, have neoadjuvant chemotherapy and neoadjuvant radiation therapy followed by surgical excision. It is just a matter of nomenclature and the effective protocols of management of the specific disease. In the referenced article by Bruce

 

Rougraff compared the aforementioned management combined with either limb salvage or amputation for the surgical resection. Turns out, while local recurrence and need for additional surgery is higher in patients undergoing limb salvage surgery, the overall mortality is about the same between the two groups. Limb salvage patients also function better - which is why the tumor society now encourages limb salvage when appropriate.

 

 

1. Neoadjuvant chemotherapy followed by surgical excision

2. Neoadjuvant chemotherapy, surgical excision, adjuvant chemotherapy

3. Surgical excision followed by radiation therapy

4. Neoadjuvant chemotherapy, surgical excision, radiation therapy

5. Surgical excision followed by adjuvant chemotherapy

6. A 7-year old boy experienced severe right hip pain following iceskating. He previously had no hip pain and is otherwise healthy. Radiographs are shown in figures A and B. What is the recommended treatment ?

    

    

    

    

    

    

   CORRECT ANSWER:2

    

   A pathological fracture is one that occurs through abnormal bone because the bone lacks its normal biomechanical properties. Benign tumors of bone that are associated with pediatric pathological fractures commonly include unicameral bone cyst, nonossifying fibroma, fibrous dysplasia, and aneurysmal bone cyst. With bone cysts, there is a high risk of fracture recurrence because of cyst persistence and the recommended treatment is ORIF with bone grafting.

    

   Dormans et al have proposed grouping the treatment of pathologic fractures. The four types of fracture treatments include: 1) no treatment-the fracture and lesion may heal spontaneously; 2) treating the fracture first and then the lesion; 3) treating the fracture and lesion simultaneously; and 4) treating only the underlying process-the fracture can heal with treatment of the underlying process.

    

   Ortiz reviews general principles of diagnosis, management, and treatment of pathological fractures in children. He emphasizes making the correct diagnosis prior to instituting any form of treatment with lesions that are not diagnostic based on preoperative imaging.

    

    

    

   1. Open biopsy and pathological staging without fracture fixation

   2. Open reduction and internal fixation with bone grafting of the bone cyst

   3. Bedrest for 4 weeks followed by progressive weight-bearing as tolerated

   4. Immediate hip spica casting

   5. Tibial traction pin with 4 weeks of skeletal traction followed by open biopsy

7. Which of the following diseases carries greater than 50% risk of developing a malignancy?

 

1. Fibrous dysplasia

2. Maffucci syndrome

3. Ollier’s disease

4. McCune-Albright syndrome

5. Multiple hereditary exostoses

 

CORRECT ANSWER:2

Maffucci’s syndrome is characterized by multiple enchondromas and soft-tissue hemangiomas with at least 50% of patients developing malignancies, either chondrosarcomas, astrocytomas or visceral adenocarcinomas. A study by Schwartz of forty-four patients with multiple enchondromas, either Ollier's or Maffucci’s syndrome, were followed and approximately 25% of Ollier's patients developed a malignancy while more than 50% of the Maffucci’s patients developed malignancy. Solitary enchondromas have only a 1% chance of malignant transformation into chondrosarcoma while patients with multiple hereditary exostosis (MHE) have roughly 10% risk of malignant transformation into chondrosarcoma.

 

 

 

5 ) A 23-year-old male reports a firm, immobile mass behind his tibia that creates pain when he walks long distances or uses stairs. He reports no night pain or constitutional symptoms. His WBC, LDH, and Alkaline phosphatase are normal. Radiographs are shown in Figures A and B. A T1 MRI is shown in Figure C. What is the next most appropriate step in management?

 

 

 

 

 

 

1. Neoadjuvant chemotherapy followed by surgical resection followed by adjuvant chemotherapy

2. Radical margin resection with allograft-prosthetic reconstruction

3. Marginal resection

4. External beam irradiation

5. Curettage with adjuvant liquid nitrogen application

CORRECT ANSWER:3

 

The clinical presentation is consistent with a symptomatic pedunculated osteochondroma. The next most appropriate step is marginal resection.

 

Osteochondromas are benign lesions, and therefore treatment is dictated by the severity of the symptoms they produce, the skeletal maturity of the patient, and concern for malignant transformation. If the symptoms are tolerable, excision is delayed until patient reaches skeletal maturity or for as long as possible due to increased risk of recurrence. In a more symptomatic skeletally immature patient, marginal excision is performed. Depending on the location, an additional concern for these patients is periarticular deformity or limb length inequality after removal. In skeletally mature patients, marginal excision is the treatment with very low risk of local recurrence. Concern for malignant transformation, found in less than 1% of patients, is an indication for wide resection.

 

Gitelis et al. discussed osteochondromas addressing general characteristics, presentation, and management options. Nonsurgical management is used in asymptomatic patients with no concern for malignant degeneration. Surgical excision is indicated in patients who have pain, interference with joint function, or impingement of the mass on neurovascular structures. These symptomatic tumors are usually treated with marginal resection, but there is the option of intralesional excision in skeletally mature patients. If there is concern for malignant degeneration, wide resection is performed for all patients.

 

Figure A and B are radiographs of an osteochondroma in which the cortex of the lesion and the underlying cortex are continuous. Figure C is a sagittal cut of a T1-weighted MRI image showing the high signal features of fatty marrow extending from the medullary canal of the tibia up into the bony stock of the pedunculated osteochondroma.

 

Incorrect Answers:

Answer 1: Osteochondromas are not treated with chemotherapy.

Answer 2: Osteochondromas that have undergone malignant transformation undergo radical resection. There is no concern for this in the patient stem.

Answer 4: Osteochondromas do not benefit from radiation therapy. Answer 5: Surgical treatment options of osteochondromas does not include curettage or liquid nitrogen therapy.

 

 

 

1. A 51-year-old female with known metastatic breast cancer presents with acute right thigh pain and inability to bear weight. A radiograph is shown in Figure A. A biopsy is performed that confirms metastatic breast cancer. What is the next step in management?

    

    

    

    

    

   1. Local radiation therapy

   2. Intramedullary nailing only

   3. Intramedullary nailing and chemotherapy

   4. Intramedullary nailing, radiation therapy to the tumor site, and chemotherapy

   5. Intramedullary nailing, radiation therapy to the entire femur, and chemotherapy

    

   CORRECT ANSWER:5

    

   This patient is presenting with biopsy proven metastatic breast cancer and a pathological fracture. The treatment in this situation is intramedullary nailing with postoperative radiation therapy to the entire femur and chemotherapy.

   Due to the process of placing the intramedullary nail, the treating surgeon contaminates the ENTIRE femur with breast cancer. The surrounding area is already contaminated with tumor cells from the fracture, however. While the intramedullary nail will stabilize the pathological fracture, it does nothing to control the local progression of breast cancer in this patient's leg. Local radiotherapy will not only improve the local control of disease but it will palliate the patient's cancer related pain.

    

   Weber et al review bone metastasis to the femur and propose valuable treatment pearls for clinical decision making and the biology which prevents cancer bearing bones to heal properly despite appropriate mechanical stabilization.

    

   Swanson et al review the role of the orthopaedic surgeon in evaluating and treating metastatic bone disease, paying close attention to the necessity to obtain a tissue diagnosis in the event of presumed metastatic disease PRIOR to proceeding with any treatment plan.

    

    

    

    

2. All of the following locations are common sites for giant cell tumor of bone to occur EXCEPT?

    

   1. Posterior elements of the spine

   2. Distal femur

   3. Sacrum

   4. Distal radius

   5. Proximal tibia

    

   CORRECT ANSWER:1

    

   As reviewed by Robert Turcotte in the referenced article, the most common locations for giant cell tumor of bone to occur are about the distal femur/proximal tibia, distal radius, and the sacrum. The spine is an uncommon location for giant cell tumors, and when they occur, they usually occur in the vertebral body, not the posterior elements. In the axial skeleton, the sacrum is a common location for giant cell tumor of bone. Outside of the sacrum, giant

   cell tumor of bone is characteristically an epiphyseal/metaphyseal lesion. As discussed in the in vitro study by Gortzak et al, treatment of giant cell tumor of bone includes aggressive intralesional curettage augmented with adjuvant treatment like hydrogen peroxide, argon beam, liquid nitrogen, or phenol. Due to the morbidity of the surgical treatment, and the less than perfect long term outcome, adjuvant therapy with an antibody against RANKL called denosumab is currently being investigated in multiple centers across North America as described by Thomas et al in their phase 2 study. Denosumab inhibits osteoclast mediated osteolysis and treatment is associated with improved bone stock and sclerosis of the GCT lesions. While denosumab doesn't obviate the need for surgical excision, the resulting surgical procedure is less extensive and early data may suggest a decreased risk of local recurrence.

   While giant cell tumor of bone is a benign condition, there is a small chance for pulmonary seeding of giant cell metastases. This occurs in somewhere between 2-5% of patients with primary giant cells and occurs more often in patients with recurrent disease.

    

    

    

    

3. A 59-year-old female presents with a metastatic spinal tumor and has a lytic lesion in the T12 vertebral body. The process of bone resorption in her lytic lesion is mediated by

    

   1. Direct resorption of bone by tumor cells

   2. Neoangiogenesis of the vertebral body

   3. Macrophage-mediated bony destruction

   4. Tumor induced activation of osteoclasts

   5. Necrosis of the vertebral body

    

   CORRECT ANSWER:4

    

   Metastatic tumors are thought to induce osteolysis not by direct resorption of bone (remember only osteoclasts can destroy bone) but rather by releasing osteoclastogenic inflammatory cytokines.

    

   Okeefe et al present a Level 5 review that states TNFa, RANKL, IL-1b, and IL-6 are osteoclastogenic inflammatory cytokins. Among these, RANKL is the most

   notable and important cytokine. It binds to RANK, a surface receptor, and initiates osteoclastogenesis.

    

   Goltzman presents a Level 5 review of the skeletal manifestations of malignancy. They report that by binding and neutralizing RANKL, osteoprotegrin (OPG) can diminish the production of functioning osteoclasts, and this factor has been shown to block bone resorption that is associated with malignancy.

    

   Illustration A is a schematic representation of tumor-cell induced osteolysis.

    

    

    

    

    

4. Patients with which of the following conditions have the highest incidence of malignant tumor?

    

   1. Single enchondroma

   2. Single osteochondroma

   3. Multiple hereditary exostosis

   4. Ollier's disease

   5. Maffucci's syndrome

    

   CORRECT ANSWER:5

    

   Of all the listed cartilage lesions, patients with Maffucci's syndrome have the highest risk of malignant tumor - estimated to be 100% over the lifetime of the patient.

   Single enchondromas and osteochondromas have a 1% risk of malignant transformation. Multiple hereditary exostosis patients have approximately a 10 % life time risk of malignant transformation. Ollier's disease is one of multiple enchondromas and carries a 30% risk of malignant transformation ( Illustration A) while Maffucci's syndrome is multiple enchondromas with hemangiomas (Illustration B). Maffucci's is also associated with a large number of other malignancies—particularly, pancreatic and hepatic adenocarcinoma, mesenchymal ovarian tumors, brain tumors such as glioma and astrocytoma, and various kinds of sarcomas.

    

   While patients with enchondromas and osteochondromas do have a slight elevation in the risk for malignant transformation, it is not as great as those patients with Ollier's disease or Maffucci's syndrome. Distinguishing enchondromas from low grade chondrosarcomas can be done by looking at radiograph features such as the degree of endosteal scalloping on radiographs and the clinical presence of pain, both associated with low grade chondrosarcomas.

    

   Ryzewicz et al review the diagnosis, pathology, and recommended treatment for patients with benign cartilage lesions. They recommend periodic follow-up even for the most benign lesions to track for malignant degeneration.

    

    

    

    

    

    

    

5. A 44-year-old male reports a mass at his right iliac crest that bothers him when he wears a belt. He denies constitutional symptoms

    

    

    

    

    

    

    

    

   and has no bowel function disturbance. His ESR and CRP are normal. His chest CT is normal. Pelvis radiograph, CT, and MRI images are shown in Figures A-D. A biopsy is performed with histology shown in Figure E. What is the next most appropriate step in management?

    

    

    

    

    

    

   1. Repeat CT scan in 3 months

   2. Neoadjuvant radiation followed by marginal surgical resection followed by adjuvant chemotherapy 3 . Marginal surgical resection

   1. Wide surgical resection

   2. Neoadjuvant chemotherapy followed by marginal surgical resection followed by adjuvant chemotherapy

    

   CORRECT ANSWER:4

    

   The history, imaging, and biopsy is consistent with chondrosarcoma and is appropriately treated with wide surgical resection. Chondrosarcoma is a malignant tumor of cartilaginous origin. It can be a primary lesion but may also develop from a preexisting cartilaginous lesion (e.g., osteochondroma, enchondroma). On plain radiographs, chondrosarcoma is typically visualized as a destructive, lytic lesion. Extension into surrounding soft tissues is frequently seen and delineated well on MRI. The characteristic chondroid matrix (rings

   and arcs) can be seen on radiographs (70%), and better visualized by CT. The histology generally demonstrates enlarged, pleomorphic chondrocytes with multinucleated lacunae.

    

   Level 4 evidence by Lee et al reviewed 227 patients with chondrosarcoma with an average follow-up of 6 years. They found that “patients who had had a resection with wide margins (margins extending outside the reactive zone) had a longer duration of survival than did those who had had a so-called marginal resection (margins extending outside the tumor but within the reactive zone) or an intralesional resection (margins within the lesion) (p < 0.04)."

    

    

    

6. Sixty Gy is a typical radiation dose for which of the following indications?

 

1. Prevention of post-operative heterotopic ossification

2. Neoadjuvant radiation therapy for a high-grade chondrosarcoma

3. Adjuvant radiation therapy for a high-grade osteosarcoma

4. Adjuvant radiation therapy for a soft-tissue sarcoma

5. Palliative therapy for a painful adenocarcinoma metastasis in the thoracic spine

 

CORRECT ANSWER:4

 

Sixty Gy (or 6000 cGy) is a typical radiation dose for adjuvant radiation therapy for a soft-tissue sarcoma.

 

External beam radiotherapy plays a major role in the treatment of soft-tissue sarcomas following limb salvage surgery. Radiation doses can vary between 45 and 65 Gy. Any dose of XRT compromises wound healing, but especially those of 45 Gy (delayed healing) and 60 Gy (not expected to heal).

 

Incorrect Answers:

Answer 1: Prevention of post-operative heterotopic ossification typically uses radiation doses of ~ 6 Gy (600 cGy).

Answer 2: Radiation is not typically used for chondrosarcoma. Answer 3: Radiation is not typically used for osteosarcoma.

Answer 5: Radiation for metastatic bone lesions is usually around 30 Gy (3000 cGy).

 

 

 

12 ) Giant cell tumors of bone can occur in many different areas throughout the body. All of the following are common locations for giant cell tumors of bone EXCEPT?

 

1. Sacrum

2. Distal radius

3. Tibial diaphysis

4. Distal femur

5. Phalanges of the hand

 

CORRECT ANSWER:3

 

Giant cell tumors are common around the knee, distal radius, sacrum and hands. They are not typically found in the diaphysis of bone.

 

Giant cell tumors are one of the more common tumors in young adults 22-40 years of age. There is much argument as to whether giant cell tumors arise in the metaphysis or the epiphysis, but most authors agree that giant cell tumors are very uncommon in the diaphysis. The most common sites of giant cell tumors in bone, which are the distal radius, sacrum, distal femur, proximal tibia and proximal humerus. Treatment typically involves intralesional curettage with adjuvant treatment (e.g., phenol, hydrogen peroxide, argon beam, etc).

 

Williams et al undertook a prospective study to evaulate the recurrence rate of giant cell tumors of the hand and they found that soft tissue extension of the tumor significantly increased the rate of local recurrence. This finding is significant because multiple previous studies have demonstrated similar higher recurrence rates for giant cell tumors with soft tissue extension in other areas like around the knee and the distal radius.

Illustration A are radiographs classic for a giant cell tumor showing a large lytic metaphseal-epiphyseal lesion in the distal femur. Illustration B is an axial CT of the distal femur showing the lytic giant cell tumor, abutting and fracturing the subchondral bone. Illustration C is histology classic for a giant cell tumor where the nuclei of the multi-nucleated giant cells look identical to the nuclei of the stromal cells.

 

Incorrect Answers:

Answers 1,2,4,5: Giant cell tumors are common around the knee, distal radius, sacrum and hands.

 

 

 

 

 

 

 

 

1. What is the most appropriate treatment for a 65-year-old female with a 100-pack-year tobacco history who presents with a new painful lytic lesion in her femoral diaphysis?

   1. Antegrade femoral nailing with reamings sent to pathology for analysis

   2. Antegrade femoral nailing with adjuvant radiotherapy to the lesion 3

      . Minimally invasive plating of the femur for stabilization and open cementation of the lesion

      1. Referral to medical oncology for chemo-radiotherapy

      2. Lesion biopsy with further treatment based on the results of the biopsy

       

      CORRECT ANSWER:5

       

      New lesions which are not diagnosed by imaging and require surgical intervention need to have an appropriate biopsy with treatment dictated by the results of the biopsy. While this patient has a significant tobacco history, incorrect treatment of this lytic bone lesion could affect both her overall morbidity and mortality. As an example, a lytic high-grade chondrosarcoma may look exactly like a metastatic lesion but requires wide surgical excision, not just stabilization of an impending pathological fracture. Intramedullary nailing of a chondrosarcoma would spread the tumor the entire length of the bone and likely require a major amputation, not a limb salvage operation.

       

       

       

2. A 14-year-old child is referred to your office for evaluation of a tibia lesion found incidentally after a minor ankle injury. A radiograph of the child's ankle is shown in Figure A. What treatment do you suggest?

    

    

    

   1. Endocrine consultation secondary to associated endocrine abnormalities

   2. Surgical consultation secondary to associated gastrointestional cancers

   3. Short leg cast and non-weight bearing for a minimum of 6 weeks

   4. Open biopsy and tumor staging

   5. Routine followup of tibial lesion

    

   CORRECT ANSWER:5

    

   The radiograph is classic for a non-ossifying fibroma given the classic eccentric position, sclerotic margin, and benign appearance. Other than routine followup for the tibial lesion, this child requires no subsequent treatment. Marks and Bauer review the diagnosis, imaging, and treatment of many different fibrous tumors of bone and review the diagnostic imaging criteria specific to each subclass of bony fibrous tumors.

    

    

    

3. The chromosomal translocation t(X;18)is found in which of the following conditions?

 

1. Myxoid liposarcoma

2. Synovial Sarcoma

3. Osteosarcoma

4. Ewing's Sarcoma

5. Clear cell sarcoma

 

CORRECT ANSWER:2

 

Synovial sarcoma is a rare soft tissue sarcoma with biphasic features of both spindle cell and epithelial differentiation. Synovial sarcoma is a rare high-grade tumor that spreads along fascial planes and, thus, can be much more widespread than apparent on initial evaluation. Males are more commonly affected than females with a ratio of 1.1:1. Synovial sarcoma is characterized by a specific chromosomal translocation t(X;18)(p11;q11) that is observed in more than 90% of cases. The t(X;18)(p11;q11) translocation fuses the SYT gene from chromosome 18 to either of 2 homologous genes at Xp11, either SSX1 or SSX2. The fusion proteins SYT-SSX1 and SYT-SSX2 function as aberrant transcriptional regulators, resulting in either activation of protooncogenes or inhibition of tumor suppressor genes.

 

Kawai et al found that SYT-SSX fusion transcripts are a defining diagnostic marker of synovial sarcomas. These fusion transcripts may yield important independent prognostic information and provide important information for different types of treatment.

 

Incorrect Answers

Answer 1: Myxoid liposarcoma is associated with chromosomal translocation t(12;16)

Answer 4: Ewing's sarcoma with t(11;22)

Answer 5: Clear cell sarcoma with (12;22), Myxoid Chondrosarcoma with t(9;22),

 

 

 

16 ) A 75-year-old man presents with a displaced femoral neck fracture. During your surgical exposure for a hemiarthroplasty, the femoral neck has fractured through a pathologic lesion which is diagnosed as a lymphoma on frozen section. The lesion is located in the center of the femoral neck and the calcar femorale is not involved.

Your treatment should include:

1. Closure of the wound and chemotherapy

2. Radical resection of the proximal femur and megaprothesis hemiarthroplasty

3. Hemiarthroplasty with postoperative staging and chemo-radiotherapy as indicated

4. Bone marrow transplantation

5. Hip disarticulation

 

CORRECT ANSWER:3

 

This case presents a treatment dilemma for most orthopaedic surgeons. However, because lymphomas are very chemo-radiotherapy sensitive, treatment is straightforward. Lymphoma isolated to bone is treated by resection and reconstruction as indicated. In this case, the resection is accomplished with neck osteotomy and the reconstruction with a hemiarthroplasty. Postoperative adjuvant radiotherapy and chemotherapy can be used to treat the local and distant disease as necessary. You wouldn't close the wound without surgical fixation unless the chemotherapy would be used to improve your surgical margin (such as for a osteosarcoma). Radical resection or hip disarticulation are very aggressive and morbid procedures for a tumor that is very sensitive to chemo-radiotherapy. Bone marrow transplantation is not used in the initial treatment of lymphoma, but can be considered for relapsed disease.

 

The clinical and radiographic features specific to lymphoma of bone are outlined by Dürr but on the whole are not diagnostic.

 

Vose describes the current treatment protocols for patients with non-Hodgkin's lymphoma including patients with impending/sustained pathologic fractures.

 

 

 

17 ) A 30-year-old man has had leg pain for 6 months. A lesion is identified in the proximal femur and biopsy it taken. Histology is shown in Figure A and is consistent with a low-grade intramedullary osteogenic sarcoma. Additional imaging studies confirm that this is an

isolated lesion with no metastasis. What is the standard treatment for this type of lesion?

 

 

 

1. chemotherapy and surgery

2. chemotherapy only

3. surgery only

4. radiation and surgery

5. radiation only

 

CORRECT ANSWER:3

 

The histology shows "lacey" osteoid with minimal cellular atypia. This is consistent with low-grade intramedullary osteogenic sarcoma. Low grade central osteogenic sarcoma is an uncommon form of osteosarcoma that is characterized by a long premorbid history and is compatible with prolonged survival after treatment. Treatment is surgery with wide margins alone and chemotherapy and radiation are not indicated. Good local control is associated with an excellent long term survival.

 

Choong et al. reviewed the long term follow-up of 20 patients diagnosed with low grade osteogenic sarcoma and found the 5 year survival rate was 90% and at 10 years was 85%. Local recurrence is a key feature in most cases and is typically the result of inadequate surgical margins frequently arising from initial misdiagnosis. Although amputation generally is successful for primary and recurrent tumors, limb salvage surgery is a definite option.

 

Kurt et al reviewed 80 well-differentiated osteosarcomas. They found local excision was almost always associated with recurrence. Wide excision was

almost never followed by recurrence. The recurrent tumor was a high-grade, conventional osteosarcoma in 15% of the patients, and this was associated with a poor prognosis. They recommend wide excision as the treatment of choice for this very rare variant of osteosarcoma.

 

 

 

1. A 32-year-old male sustains a the injury shown in Figure A after a high-speed motor vehicle collision. Which factor has been found to have the highest direct correlation with severe heterotopic ossification after traumatic knee dislocation?

    

    

    

    

    

   1. Injury Severity Score (ISS )

   2. Glascow Coma Scale (GCS )

   3. Timing of knee reconstruction

   4. Number of ligaments reconstructed

   5. Open ligament reconstruction

    

   CORRECT ANSWER:1

   Figure A shows a knee dislocation with cruciate ligament avulsion injuries. Development of significant heterotopic ossification (HO) formation has been shown to be most directly correlated to the ISS score.

    

   Mills and Tejwani looked at multiple variables including injury severity score

   ( ISS), Glascow coma scale (GCS), closed head injury (CHI), timing of surgery (> or < 3 weeks) and type of surgery (open vs. arthroscopic, number of ligaments reconstructed) in its relation to the formation of HO following knee dislocation. In the final group the sensitivity and specificity of the ISS in relation to HO formation was 100%, while presence of CHI had a specificity of 97 %. Timing, type of surgery and approach did not influence HO formation.

    

    

    

2. A 52-year-old male presents with 6 months of swelling and pain in his leg. He states the lesion has not changed in size for several months and doesn't bother him. He is otherwise healthy and has no other complaints. Representative photograph and MRI are shown in Figures A through C. What is the best initial step in his management?

    

    

    

    

    

    

    

    

   1. Follow-up in 6 months with repeat radiographs

   2. Biopsy

   3. Marginal excision

   4. Radiation therapy

   5. Neoadjuvant chemotherapy and wide excision

    

   CORRECT ANSWER:2

    

   The initial step in management of a patient presenting with a large soft tissue mass deep to the fascia is to obtain a tissue diagnosis, via biopsy. Initiation of treatment prior to tissue diagnosis is inappropriate and can result in significant patient morbidity and potential mortality. While some soft tissue sarcomas may benefit from chemotherapy, this cannot be initiated prior to diagnosis.

   Radiation therapy is used in the treatment of soft tissue sarcoma, but again, only after tissue diagnosis. Peabody et al review the appropriate evaluation and staging for musculoskeletal neoplasms and present flow-charts useful in the work-up of bone (Illustration A) and soft tissue (Illustration B) neoplasms. Skrzynski et al performed a comparison of outpatient core-needle biopsy with open surgical biopsy for musculoskeletal tumors. They found the diagnostic accuracy of core-needle biopsy was only 84% with many samples yielding no or different histological samples when compared to final resected specimens. They conclude that while core-needle biopsy is significantly less expensive

   than surgical biopsy ($1106 vs. $7234), there is higher concern for sampling error or general diagnostic inaccuracy associated with a core-needle biopsy compared to open biopsy, the "gold standard".

    

    

    

    

    

    

    

    

3. What is the appropriate treatment for a 10-year-old boy with Ewing's sarcoma isolated to the proximal femur?

    

   1. Neoadjuvant chemotherapy and surgical excision

   2. Neoadjuvant chemotherapy, surgical excision, and radiation therapy

   3. Neoadjuvant chemotherapy, surgical excision, and adjuvant chemotherapy

   4. Neoadjuvant radiation therapy and surgical excision

   5. Surgical excision and hormonal therapy

    

   CORRECT ANSWER:3

   Ewing's sarcoma is a malignant small round blue cell neoplasm which has a predilection for long tubular bones, pelvis, and ribs. The radiographic appearance of "onion-skinning" seen in illustrations A and B is due to the body's periosteal reaction. Illustration C shows the large soft tissue extraosseous mass characteristic for Ewing's sarcoma. Finally, Illustration D shows the histology where the multiple small round blue neoplastic cells are seen.

   Ewing's sarcoma is most commonly treated with neoadjuvant chemotherapy, surgical excision, and adjuvant chemotherapy - in particular for tumors located in bones which can be easily resected and reconstructed. For large tumors in areas which either cannot be completely excised or where excision is associated with significant morbidity, some centers consider chemotherapy and radiation therapy without surgical excision. There is a current trend towards surgical resection and away from irradiation for Ewing's sarcoma even though it is radiosensitive, because of the risk of secondary malignancy and growth disturbance due to radiation.

   Pierz et al review many of the common bone tumors including Ewing's sarcoma and discuss the relevant diagnostic factors as well as specific treatment protocols for each tumor.

    

    

    

    

    

    

    

    

4. A 30-year-old female presents with a painful posterior knee mass. The mass gets larger and more painful with activity. Examination reveals a boggy soft tissue mass about her knee. Radiograph and MRI are shown in Figures A and B. What is the most likely diagnosis?

 

 

 

 

 

 

1. Synovial sarcoma

2. Hemangioma

3. Lipoma

4. Parosteal osteosarcoma

5. Pigmented villonodular synovitis (PVNS )

 

CORRECT ANSWER:2

 

This patients history, physical exam, and imaging studies are suggestive of a hemangioma. Pain in hemangiomas is thought to occur due to vascular engorgement secondary to activity and increased blood flow to the lesion. The calcification on the plain radiograph and the fat of the T1 MRI are diagnostic for hemangioma. Current treatment for symptomatic hemangiomas includes some combination of sclerotherapy or vascular coiling, with surgical excision

reserved for few cases. The two attached reviews by Gilbert et al and Damron et al review the history, diagnosis, treatment, and controversial issues in soft tissue sarcomas and benign sarcoma like conditions such as hemangiomas.

Current treatment for soft tissue sarcomas includes radiotherapy and surgical excision. While many centers in the world use chemotherapy for soft tissue sarcomas, the data supporting its use is quite limited and likely too controversial to be tested. With regard to the other answer choices, synovial sarcoma and lipoma can show calcification on radiographs, but they are usually not painful and image differently on T1 MRI. Parosteal osteosarcoma typically occurs in this location (posterior distal femur) but occurs as a lesion stuck on the bone. PVNS can have a similar appearance on imaging, but doesn't cause this type of pain.

 

 

 

 

22 ) A 62-year-old male with a 50-pack-year history of tobacco use presents with complaints of productive cough and increasing leg pain for the past 6 months. Proximal tibial radiographs are shown in Figures A and B, and are concerning for an impending pathologic fracture. CT of the chest, abdomen, and pelvis, and staging blood work are negative. MRI of the tibia shows a multi-focal cortically based lesion without significant soft tissue mass and whole body technetium bone scan shows this to be an isolated lesion. What is the next most appropriate step in management of this patient?

 

 

1 . Intramedullary nailing of the tibia and send canal reamings to pathology

2 . Radiotherapy for palliative pain control as the risk for pathological fracture is very small

1. Open incisional biopsy

2. Chemotherapy and surgical stabilization with intramedullary nailing of the tibia

3. Radiotherapy and surgical stabilization with intramedullary nailing of the tibia

 

CORRECT ANSWER:3

 

Treatment for musculoskeletal oncology depends on a correct tissue diagnosis, which in this patient requires an open incisional biopsy. Despite the concern that this lesion may represent a metastasis from lung carcinoma, without tissue diagnosis, treatment cannot ensue. Regarding concerns for pathologic fracture, this patient would be best managed with no weight bearing until a diagnosis can be determined. If this lesion is a sarcoma, then despite the patient's pain and risk of pathologic fracture, neo-adjuvant chemotherapy and wide surgical resection will be needed for the best chance at local control and patient survival. While intramedullary nailing of the tibia and sending canal reamings to pathology may either appear appropriate or be performed at

some centers, this procedure may contaminate the entire bone with tumor and make limb salvage nearly impossible if this is a sarcoma. If the incisional biopsy shows carcinoma, then intramedullary nailing with adjuvant radiotherapy would be completely appropriate.

 

 

 

23 ) A 10-year-old boy has 2 months of right knee pain that started at summer camp. The patient denies constitutional symptoms. There is no lymphadenopathy present. CT of the chest shows no signs of metastatic disease. Imaging studies and biopsy results are shown in Figures A-E. What is the most likely diagnosis?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1. Synovial sarcoma

2. Malignant fibrous histiocytoma

3. Chondrosarcoma

4. Ewing's sarcoma

5. Osteosarcoma

 

CORRECT ANSWER:5

 

The age, imaging and histology are consistent with an osteosarcoma. The radiograph shows an aggressive (lytic, mottled, sclerotic) appearing lesion around the distal femur metadiaphyseal region. The T2 weighted MRI image shows a significant soft tissue mass which appears to arise from the distal femur with destruction of the adjacent cortex. The biopsy shows an infiltrative pattern with elements of osteoid and bone.

Treatment for osteosarcoma includes neoadjuvant chemotherapy, wide resection, and adjuvant chemotherapy.

 

 

 

 

24 ) A 79-year-old healthy male has 1 year of progressively worse left hip pain. He denies any significant weight loss but does complain of night pain. Radiograph and MRI are shown in Figures A & B. Bone scan and histology is shown in Figures C-E. What is the definitive treatment of this?

 

 

 

 

 

 

 

 

1. observation

2. radiation therapy alone

3. wide resection and reconstruction

4. wide resection, reconstruction and chemotherapy

5. wide resection, reconstruction and local radiation therapy.

 

CORRECT ANSWER:3

 

The history, imaging and pathology points to chondrosarcoma as the diagnosis, and therefore wide resection and reconstruction is the most appropriate treatment.

 

Chondrosarcoma tends to occur in an older individuals and the most common sites of origin are the femur, tibia, humerus, ribs, scapula then pelvis.

Chondrosarcomas grow slowly and patients present with dull aching pain.

 

X-rays typically have a subtle, radiolucent, permeative lesion or may have hazy or speckled calcifications with either a diffuse "salt & pepper" pattern or a more discrete "popcorn" pattern. The MRI defines the amount of marrow and soft-tissue involvment, and typically has high T2 signal intensity. Bone scintigraphy will be positive.

 

In pathological sections, low-power imaging demonstrates lobulated clusters of chondrocytes, and high-power imaging demonstrates a bland cellular appearance, extensive basophilic cytoplasm, and no mitotic figures (low grade chondrosarcoma).