The patient has sustained a pathologic fracture through an undiagnosed enchondroma of the proximal phalanx of the small finger. An enchondroma is the most common bone tumor of the hand.1 Enchondromas are benign, slow-growing, cartilaginous tumors that most commonly affect patients aged 20 to 50 years.2
Most enchondromas are asymptomatic and commonly present as an incidental finding or as a pathologic fracture.2 Large enchondromas that expand across the phalanx and erode the bony cortex can cause a pathologic fracture with only minor trauma. Cortical thinning, expanding, or disruption should raise suspicion of a more aggressive tumor such as chondrosarcoma or benign giant cell tumor.1,2
Most enchondromas can be diagnosed with radiographs alone but any suspicion of malignancy warrants magnetic resonance imaging with contrast. Patients who present with a pathologic fracture through an enchondroma can be treated conservatively with immobilization with a splint as the fracture may stimulate healing of the lesion. Recently, surgical treatment with immediate curettage and bone grafting has become popular to minimize the period of immobilization required.1,2
1. Lubahn JD, Bachour A. Enchondroma of the hand: evaluation and management.
J Am Acad Orthop Surg. 2016;24(9):625-633. doi:10.5435/JAAOS-D-15-00452
2. Woon C. Enchondroma. OrthoBullets. Accessed March 23, 2021. https://www.orthobullets.com/pathology/8018/enchondromas