Subungual Reactive Eccrine Syringofibroadenoma: A Case Report

Eccrine syringofibroadenoma was initially described by Mascaró in 1963 as a possible "eccrine" counterpart of Pinkus fibroepithelioma. Later, Nomura et al, reported a case of bullous pemphigoid associated to syringofibroadenomatous hyperplasia of the palms and soles, suggesting that this entity corresponds to hyperplasia of the eccrine ducts rather than a true neoplasm. There are currently numerous publications that support this hypothesis, describing similar changes induced by different alterations of the papillary dermis, either associated to inflammatory reactions or even neoplastic diseases. Despite the fact that these changes are already well-known, there are very few published cases of this condition in its subungual location. We believe that it is important to highlight this information so dermatologists and pathologists can include it among their differential diagnoses. Histopathological findings can be very subtle, and if not known, they can go unnoticed, leading to a nonspecific diagnosis, creating uncertainty for both the patient and the treating physician.