Orthopedic Teaching Cases 2023, Jan, 18 | 12:00 am

Orthopedic Oncology cases undifferentiated pleomorphic sarcoma

A 33-year-old male presents to your office with a slow-growing area of swelling

that he has noticed about the medial aspect of his ankle for the past 18 months. It is nontender, and he reports no history of trauma. He has received several injections into the ankle by his primary care provider, with no relief from the swelling. Extensive workup has been negative, and x-rays reveal small areas of calcification in the area anterior to the medial malleolus. MRI reveals a soft-tissue mass in the anteromedial ankle area, which is low intensity on T1-weighted images and high intensity on T2-weighted imaging.

You are concerned for a soft-tissue sarcoma. Which of the following is the most common soft-tissue sarcoma found in the foot and ankle region?

  1. Epithelioid sarcoma

  2. Synovial sarcoma

  3. Angiosarcoma

  4. Leiomyosarcoma

 

Discussion

The correct answer is (B). Synovial sarcoma is the most common soft-tissue sarcoma found in the foot and ankle region.

In addition to a staging workup you order an image-guided biopsy. The slide is shown in Figure 8–30. What is this patient’s diagnosis?

  1. Epithelioid sarcoma

  2. Synovial sarcoma

  3. Angiosarcoma

  4. Leiomyosarcoma

 

 

 

Figure 8–30

Discussion

The correct answer is (B). Histology of a synovial sarcoma shows a monophasic or biphasic pattern of cuboid epithelioid cells (lower right of slide and scattered areas) and fibrosarcoma-like spindle cells (remainder of slide). The epithelial cells are arranged in nests or chords, and the fibrous component involves plump, malignant spindle cells within minimal cytoplasm and dark nuclei.

Which of the following immunohistochemical stains is used to support this diagnosis?

  1. Keratin

  2. S-100

  3. Intracellular melanin

  4. Collagen

 

Discussion

The correct answer is (A). Synovial sarcoma stains positive with keratin. S-100 is positive in nerve tumors. With appropriate staining, intracellular melanin is noted in about 50% of patients with clear cell sarcoma.

What is the chromosomal translocation in synovial sarcoma, and what fusion products result from this translocation?

  1. t(12;22); EWS-ATF1

  2. t(12;16); CHOP-TLS

  3. t(11;22); EWS-FLI1

  4. t(x;18); SYT-SSX

 

Discussion

The correct answer is (D). The fusion product SYT-SSX1 or SYT-SSX2 is the result of a balanced chromosomal translocation t(x;18) in synovial sarcoma. Choice A represents the translocation associated with clear-cell sarcoma. Choice B represents the translocation in myxoid liposarcoma, and choice C represents the translocation in Ewing sarcoma.

 

Objectives: Did you learn...?

 

 

To recognize synovial sarcoma imaging and histology? Synovial sarcoma genetics and immunohistochemical staining?

CASE                               26                               

A 60-year-old male is diagnosed with a 6-cm deep high-grade undifferentiated pleomorphic sarcoma (UPS) of the soft tissue of his upper arm.

What is true about this malignancy?

  1. It is the most common soft-tissue sarcoma in adults 55 to 80 years of age

  2. It is derived from a neurovascular bundle, therefore neurologic symptoms are common

  3. The balanced translocation associated with this malignancy is t(12;16)

  4. Overall survival at 5 years is 95% if negative margins can be achieved

 

Discussion

The correct answer is (A). This diagnosis represents the most common soft-tissue sarcoma in adults 55 to 80 years of age. Although these tumors may involve nerves or vessels, UPS is not necessarily derived from a nerve or vessel, unlike MPNST or angiosarcoma. The translocation t(12;16) is associated with myxoid liposarcoma; there is no specific genetic defect associated with UPS, rather it is the category in which all sarcomas that are not otherwise specifically identified fall. Treatment is radiation and wide surgical resection, with chemotherapy in selected cases, and overall 5-year survival is 50% to 60%. UPS was formerly called MFH, or malignant fibrous histiocytoma, which is a term that is no longer used by modern sarcoma pathologists and is no longer acceptable nomenclature.

You recommend external beam radiation in conjunction with wide resection as treatment. Which of the following is true regarding external beam radiation therapy?

  1. Postoperative radiation is associated with higher risk of wound-healing complications

  2. Postoperative radiation is associated with a higher dose of irradiation

  3. Preoperative radiation is associated with a higher risk of long-term fibrosis

  4. Preoperative radiation is associated with a wider field of radiation

 

Discussion

The correct answer is (B). External beam radiation can be administered preoperatively or postoperatively with equivalent local control rates. Preoperative XRT followed by wide surgical resection is associated with a higher risk of wound-healing complications, a lower risk of long-term fibrosis, and a lower total dose of

irradiation, administered to a smaller anatomical field.

 

Undifferentiated pleomorphic sarcoma (UPS) can develop as a secondary malignancy in each of the following except:

  1. Fibrous dysplasia

  2. Radiation to an area for treatment of a prior malignancy

  3. Osteochondroma

  4. Bone infarct

 

Discussion

The correct answer is (C). UPS of bone or soft tissue has been associated as a secondary lesion with fibrous dysplasia, bone infarcts, Paget sarcoma, and postradiation. Chondrosarcoma can develop as result of malignant transformation of osteochondroma.

 

Objectives: Did you learn...?

 

Clinical features of undifferentiated pleomorphic sarcoma?