X-ray showing a bone lesion of the proximal phalanx of the fourth toe
Coronal short tau inversion recovery sequence magnetic resonance imaging of the patient’s foot
A 45-year-old woman presents with a bone lesion found on x-ray by her primary care physician. The x-ray shows a bone lesion of the proximal phalanx of the fourth toe. Coronal magnetic resonance imaging was taken as well. The patient’s fourth toe has been painful during running for the last month and seems to be getting worse. You are concerned that the patient has a stress fracture through the lesion.
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A diagnosis of enchondroma was made. Enchondroma is the second most common benign bone tumor behind osteochondroma. The intramedullary lesion is thought to be an island of cartilage within bone that never ossified. Half of all enchondromas can be found in the small tubular bones of the hands and feet, with most found in the phalanges.
Enchondromas typically present asymptomatically as a solitary radiolucent lesion found incidentally or as a pathologic fracture. However, enchondromas of the hands and feet can present symptomatically as stress fractures. The patient’s x-ray in our case shows classic findings of an enchondroma, including a centrally located radiolucent metaphyseal lesion with cortical thinning of the proximal phalanx. The lesion appears benign and lacks findings that suggest malignancy, including soft tissue involvement, loss of matrix mineralization, or cortical destruction.1
Impending fractures or pathologic fractures of the small tubular bones of the hands and feet should be treated with immobilization until the fracture heals, followed by intralesional curettage and bone grafting. Biopsy at the time of curettage should be performed to rule out malignant transformation to chondrosarcoma.
In our case, after a period of immobilization, the patient underwent intralesional curettage, biopsy, and allograft bone grafting. A high-speed bur was used intraoperatively to ensure removal of the entire tumor from surrounding bone. The fourth toe was pinned in a reduced position, as the curettage destabilized the proximal phalanx. Postoperative pathology findings included fragments of hyaline cartilage consistent with an enchondroma. The pin was removed 4 weeks postoperatively when intralesional bone ingrowth was seen.
Prognosis following curettage and bone grafting is quite good, with recurrence rates of less than 5%. Any recurrence of an enchondroma suggests malignant transformation.2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Randall RL, Ward R, Hoang BH. Musculoskeletal oncology. In: Skinner HB, McMahon PJ. Current Diagnosis & Treatment in Orthopedics. 5th ed. New York, NY: McGraw-Hill Education; 2014:230-318.
- Woon C. Enchondromas.http://www.orthobullets.com/pathology/8018/enchondromas. Updated June 17, 2015. Accessed January 26, 2016.