Dermatofibroma of the eyelid with monster cells.

Dermatofibromas are most frequently encountered in women on the lower extremities, often after minor trauma. A recurrent lesion of the right lower eyelid developed in a 64-year-old woman. It harbored "monster cells" that were large, with either multiple nuclei or a single, large, convoluted, and hyperchromatic nucleus. The presence of these cells does not signify a malignant transformation. The background cells were either histiocytoid (many were adipophilin positive), spindled cells, or dendritiform cells without mitoses. Factor XIIIa, CD68, and CD163 immunostaining was positive, and a subpopulation of CD1a Langerhans cells was intermixed. Facial and eyelid dermatofibromas are more likely to recur and deserve wider, tumor-free surgical margins. Their microscopic differential diagnosis includes a cellular scar, peripheral nerve tumor, atypical fibrous xanthoma, and dermatofibrosarcoma protuberans.