Introduction: Enchondromas arise from cartilaginous cells derived from the physis that persists throughout development. They are difficult to diagnose and are often discovered on radiographs after a trauma.
Patient concerns: We discuss the case of a 32-year-old woman with a pathologic mallet fracture of the distal phalanx that was initially misdiagnosed as common mallet fracture.
Diagnosis: Magnetic resonance imaging revealed an eccentrically located lesion expanding to the cortex, with a high signal intensity at T2 weighted image, suggesting pathologic fracture.
Interventions: We performed a operation, involving curettage and bone grafting. Complete removal of the lesion was confirmed intraoperatively with the image intensifier, and the cavity was irrigated and subsequently filled with allogenous bone and demineralized bone matrix.
Outcomes: With an uneventful recovery, she gradually return to normal function within 3 months. Her symptoms improved and nearly full range of motion of the finger was seen at 1-year follow-up.
Conclusion: Our case of pathologic mallet fracture was misdiagnosed as a simple fracture, suggesting that the mechanism of fracture and radiological diagnosis should be carefully considered.