Bednar tumor: a rare neuromesenchymal neoplasm in a rare location

Bednar tumor or pigmented dermatofibrosarcoma protuberans is a rare slow-growing dermal tumor of neuromesenchymal origin having low malignant potential. It usually presents as a black, firm plaque or exophytic nodule on the back or shoulder, mostly in black people in their third to fourth decades of life. The head, neck, and extremities are less common sites. Herein, we reported a 55-year-old female presenting with a well-defined, dark-colored, ulcerated, painful plaque on the fifth toe of the right foot that had developed since two years beforehand. Malignant melanoma and dermatofibroma were considered as clinical differential diagnoses. An incisional biopsy was done. Histopathologic evaluation showed dermal proliferation of plump elongated cells and spindled cells (with oval to elongated hyperchromatic nuclei and scanty eosinophilic cytoplasm) arranged in storiform pattern and sheets. Melanin-laden dendritic cells were also present, interspersed with neoplastic elongated and spindle-shaped cells. Based on these clinical and histopathologic features, a diagnosis of Bednar tumor was made.