Unique histopathologic features of the eyelid dermatofibroma.
Purpose: Dermatofibromas are common cutaneous lesions, but rarely occur in the eyelid skin. The reason for the low incidence in the palpebral skin has not been elucidated. In this study, we analyze the histopathologic features of an illustrative case of dermatofibroma and review previously published cases to determine whether eyelid dermatofibroma develops differently from the prototypical dermatofibroma. Methods: Histopathologic analysis of a new illustrative case of eyelid dermatofibroma and retrospective review of published cases. Results: The distinguishing features of the illustrative lesion included a rounder gross appearance, nonacanthotic epithelium, basophilic staining, cellular character, and a paucity of "collagen trapping." These features deviated from the typical features associated with classic dermatofibroma. Review of the 11 previously published cases of eyelid dermatofibroma revealed that they were more similar in appearance to the illustrative lesion than to classic dermatofibroma. Discussion: The rarity and histological deviations of the eyelid dermatofibroma suggest that the dermal substrate from which the lesion develops differs from that of the classic dermatofibroma. This difference may be explained microanatomically based on the fact that the dermis of the eyelid is predominantly papillary, whereas the dermis of extrapalpebral skin where dermatofibromas are more common is predominantly reticular. Conclusions: Although related, eyelid dermatofibromas appear to be histologically distinct from classic dermatofibromas, owing to the unique dermal composition of the site of origin.