Giant, Multilobulated Spindle Cell Lipoma of the Ankle in a Middle-aged Female: An Extremely Rare Presentation

Spindle cell lipoma is a rare benign adipocytic neoplasm typically occurring in the posterior neck and back of middle-aged males. Its occurrence in the ankle region, particularly in females, represents an extremely rare presentation with only sporadic case reports documented in the literature. We report the case of a 41-year-old female who presented with a 7-year history of painless anterior ankle swelling following trauma. Physical examination revealed a 7 cm × 5 cm firm, nontender mass with preserved ankle function and normal neurovascular status. Magnetic resonance imaging (MRI) demonstrated a well-circumscribed, multilobulated, juxta-articular lesion measuring 96 mm × 61 mm × 47 mm with characteristic fat-intense signals, areas of cystic degeneration, and displacement of surrounding tendons and vessels. The lesion comprised two distinct polypoidal components causing splaying of the tibialis anterior and extensor hallucis longus tendons. Marginal excision was performed under regional anesthesia, revealing a well-encapsulated, multilobulated mass easily separable from surrounding structures. Histopathological examination showed mature adipocytes intermingled with bland spindle cells within dense collagen bundles and myxoid stroma. Immunohistochemical analysis revealed CD34 positivity in spindle cells and S-100 negativity, confirming the diagnosis of spindle cell lipoma. The patient's postoperative course was uneventful, with no evidence of local recurrence or functional deficit at 18-month follow-up. This case represents the first documented giant, multilobulated spindle cell lipoma of the ankle in a female patient. The presentation highlights the importance of considering spindle cell lipoma in the differential diagnosis of soft-tissue masses in atypical locations, particularly in female patients where unusual presentations are more common. While MRI provides valuable preoperative information, definitive diagnosis requires histopathological and immunohistochemical confirmation. Complete marginal excision offers excellent prognosis with minimal recurrence risk, reinforcing the benign nature of these lesions even in atypical presentations.