Hypertrophy of the abductor digiti minimi muscle simulating a localised soft tissue mass

Soft tissue tumours of the foot are rare and often present a difficult clinical and diagnostic situation. We report of a 15-year-old male with a painless swelling at the lateral margin of the left foot. After X-ray and MRI an excisional biopsy was performed. Histology revealed true muscle hypertrophy without myopathic or degenerative changes, consistent with the diagnosis of congenital hypertrophy of the abductor digiti minimi muscle. At a follow-up of one and a half year there was no recurrence and the patient was satisfied with the shape and the appearance of the foot.