Giant cell reparative granuloma of the calcaneus in a 32-year-old man without recurrence at 7-year follow-up: a case report.

Background: Giant cell reparative granuloma (GCRG) is a rare benign lesion, with calcaneal involvement being particularly uncommon. The differential diagnosis of osteolytic lesions in the foot remains challenging due to radiographic overlap with other entities. Case report: A 32-year-old man presented with a five-year history of recurrent left heel pain that acutely worsened over ten days. Radiography revealed an expansile, well-defined lytic lesion with a sclerotic margin in the posterior calcaneus. The patient underwent curettage and bone grafting. Histopathology demonstrated a proliferative stroma of spindle-shaped fibroblasts and myofibroblasts, accompanied by numerous osteoclast-like giant cells, foamy histiocytes, and focal hemosiderin deposition. Immunohistochemistry was positive for CD68 and EMA, negative for P63 and SMA, and showed a low Ki-67 proliferation index. At 7-year follow-up, the patient remained asymptomatic with no evidence of recurrence. Conclusions: GCRG of the calcaneus should be considered in the differential diagnosis of osteolytic foot lesions in young adults. Definitive diagnosis relies on histopathological and immunohistochemical examination. Curettage combined with bone grafting is an effective treatment that achieves long-term recurrence-free survival.