Benign Fibrous Histiocytoma of the Calcaneus: A Case Report of a Rare Bone Tumor

A benign fibrous histiocytoma (BFH) is a rare tumor that typically occurs in the pelvis and non-metaphyseal regions of long bones, making its presence in the calcaneus extremely unusual. We present the case of a 42-year-old male who experienced right heel pain for a year, initially worsening with weight-bearing on the right leg. Over the past month, the pain began occurring even at rest and was only relieved by over-the-counter analgesics. Clinical examination revealed a heterogeneous, tender swelling of the right heel without erythema or venous prominence. The calcaneal squeeze test triggered moderate to severe pain. Standard radiographs showed a cystic lesion occupying nearly the entire calcaneus, accompanied by cortical thinning and breaching. MRI displayed a lobulated area with altered signal intensity, appearing mildly hypointense on T1-weighted sequences and hyperintense on T2-weighted sequences, measuring 51 mm × 31 mm × 39 mm. A core needle biopsy from the lesion identified a few multinucleated giant cells without signs of mitosis or necrosis. After thorough discussion and obtaining informed consent, we performed an extended curettage of the lesion. We then placed ipsilateral autologous non-vascularized fibular strut grafts into the cavity, supplemented by autologous tricortical iliac crest grafts and synthetic hydroxyapatite granules as artificial bone grafts. Histopathological examination of the excised tissue revealed fascicles of spindle cells with elongated vesicular nuclei and moderate cytoplasm, interspersed with multinucleated giant cells. Correlating the clinical, radiological, and histopathological findings confirmed the diagnosis of BFH of the calcaneus. The patient achieved full weight-bearing mobility three months post-surgery. At the five-year follow-up, he remained pain-free with no signs of local recurrence and demonstrated a full range of motion in the right ankle. His American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score improved significantly from 55 at the initial visit to 100 at the final follow-up. BFH rarely affects the calcaneus, with this being only the third reported case. Due to the extensive involvement of the calcaneus, using autologous fibular strut grafts provided enhanced stability and mechanical strength. This approach proved to be more cost-effective than allogeneic bone grafts and avoided the need for additional stabilization with implants.