Case Report: Limb-threatening desmoid-type fibromatosis of the foot requiring transtibial amputation

Desmoid-type fibromatosis (DTF) is a rare myofibroblastic/fibroblastic neoplasm characterized by infiltrative growth and a tendency towards local recurrence. In its extra-abdominal form, DTF arises in the extremities, head, neck and trunk, and the chest wall, but Desmoid fibromatosis in the foot is exceptionally rare. We present the case of a 41-year-old man who presented with recurrence of a right foot tumor initially diagnosed as a benign spindle cell lesion. The diagnosis was revised to desmoid-type fibromatosis based on a CTNNB1 p.T41A mutation. Despite systemic therapies, the tumor progressed locally, requiring transtibial amputation. Foot involvement in DTF is uncommon and challenging due to anatomical constraints. Even though this condition is not considered to be malignant, the natural history of DTF may be totally unpredictable warranting radical surgical management. This case emphasizes the importance of early diagnosis and multidisciplinary management, as delayed care may result in limb-threatening progression requiring salvage amputation.