Fibro-osseous pseudotumor of the digit: Presentation as an enlarging erythematous cutaneous nodule.

Fibro-osseous pseudotumor of the digit is an unusual ossifying fibro-proliferative lesion. The current case is a 54-year-old woman who presented with an enlarging reddish nodule on the distal aspect of her left big toe. Excision biopsy was performed and the histopathology featured a dermal-centered lesion composed of osteoblast-rimmed bony trabculae lying amidst fibrovascular stroma. This entity resembles and may be within the spectrum of myositis ossificans, the prototype post-traumatic reactive fibro-osseous proliferation, although the latter is typically more proximally located and features a zonation pattern on histopathology. The distinguishing features from other pathological differential diagnoses, such as subungual exostosis and extraskeletal osteosarcoma, are discussed. The growth is considered benign and local recurrence following complete excision is unusual.