Orthopedic Oncology cases enchondroma4

A 31-year-old male is seen in the emergency room after sustaining a knee injury. He reports he was playing pickup football this morning when he twisted his knee awkwardly. He felt a pop, and his knee swelled within 20 minutes. He was able to bear weight without much pain, but reports his knee felt unstable. X-rays taken in the emergency room are negative for fracture but demonstrate a lesion in the distal femur (Fig. 8–4).

 

 

 

Figure 8–4

 

What is the most likely statement regarding this lesion?

1. It caused weakening of the bone and he likely sustained a nondisplaced pathologic fracture in this area that is not visible on x-ray

2. This is likely an incidental finding, and his pain is unrelated to the lesion

3. Extensive calcification of the lesion is concerning for malignant transformation

4. A skeletal survey is required to evaluate extent of disease

 

Discussion

The correct answer is (B). X-rays reveal many classic characteristics of an enchondroma, which is a benign tumor comprised of hyaline cartilage located in the medullary canal. Over time, the lobules of cartilage calcify, giving it the stippled, “arcs and rings” appearance on x-ray. Calcification implies a slow-growing or latent process, and areas of lucency are more concerning than calcified areas: either for sites of necrosis or more rapidly proliferating and spreading cartilage that may

be aggressive. Enchondromas are rarely symptomatic and rarely cause pathologic fracture, and furthermore the patient’s history is more consistent with an intra-articular ligamentous injury than a distal femur fracture. This enchondroma represents an incidental finding on an x-ray performed for another reason, which is often the way these lesions are diagnosed.

The patient goes on to obtain an MRI of the knee, which reveals a tear of his anterior cruciate ligament. He is put in a knee immobilizer, nonweight bearing on the extremity, and is instructed to follow-up in the office within a week. What further management should be recommended regarding the lesion in his distal femur?

1. Follow with serial radiographs to ensure stability

2. Needle biopsy on elective basis to differentiate between enchondroma and chondrosarcoma

3. Curettage and bone graft at time of ACL reconstruction

4. Referral to medical oncology for workup of visceral malignancy

 

Discussion

The correct answer is (A). Asymptomatic enchondromas require no treatment, but should be followed with serial x-rays to monitor size, calcification, and other characteristics. If radiographs are suspicious for chondrosarcoma, further workup and possible surgery is necessary. Important to note regarding cartilage tumors is that pathologic examination is not reliable to differentiate between a benign enchondroma and a low-grade chondrosarcoma; instead, radiographic appearance is more accurate and important in this differentiation. Curettage and bone grafting is reserved for symptomatic enchondromas, but this patient has a reason for his pain (the ACL tear) and was asymptomatic prior to his acute injury. Surgical treatment for the enchondroma is not indicated.

Which of the following histologic slides (Fig. 8–5A–D) represents this patient’s lesion?

1. Figure 8–5A

2. Figure 8–5B

3. Figure 8–5C

4. Figure 8–5D

 

 

Figure 8–5 A

 

 

Figure 8–5 B–D

 

Discussion

The correct answer is (B). Enchondromas are composed of hyaline cartilage demonstrating a lobulated pattern. They have variable cellularity characterized by large, round chondroblasts surrounded by purple or blue matrix on hematoxylin

and eosin (H&E) staining. Chondroblasts can be recognized by a typical “fried egg” appearance with a high proportion of cytoplasm. Nuclei can have mild atypia, with bean-shaped or even binucleate appearance, making grading of cartilage tumors by histology alone difficult. A high-power slide is shown in Figure 8–6 demonstrating these features.

 

 

 

Figure 8–6

 

If the patient reported to you that he also had enchondromas in bilateral humeri and his contralateral femur, you become concerned about related conditions that involve multiple enchondromas. Which of the following is true?

1. Ollier disease is characterized by pancytopenia and multiple enchondromas, while Maffucci syndrome does not involve hematologic abnormalities

2. Maffucci syndrome involves vascular malformations and increased rate of visceral malignancy, while Ollier disease involves increased risk of malignant transformation of an enchondroma to a low-grade chondrosarcoma

3. Patients with Maffucci syndrome have an increased risk of fracture through their enchondromas, while patients with Ollier syndrome do not

4. A critical complication of both Ollier and Maffucci syndrome is hypercalcemia due to extensive bone destruction by the enchondromas

Discussion

The correct answer is (B). Ollier disease is characterized by multiple enchondromas with a 25% to 30% risk of malignant transformation to a low-grade chondrosarcoma. Maffucci syndrome involves multiple enchondromas, vascular malformations, and a high risk of developing a visceral malignancy. Hematologic abnormalities or electrolyte disturbances are rarely associated with these conditions.

The risk of pathologic fracture in these patients is no greater than those with solitary enchondromas.

 

Objectives: Did you learn...?

 

 

 

To recognize cartilage tumors on imaging? To recognize cartilage on a histology slide? The management of benign cartilage lesions?

 

Syndromes of multiple enchondromas and their relevance?