Histopathology attributes of Fox-Fordyce disease.

Background: Fox-Fordyce disease is a rare chronic papular condition with a very characteristic clinical presentation but a nonspecific histopathology. Its traditionally described histopathologic features have been criticized as variable and indistinct. Recently, a perifollicular infiltrate of histiocytes with foamy cytoplasm has been described as a consistent and reliable diagnostic finding.

Methods: To evaluate the traditional and most recently described histopathologic and immunohistochemical attributes of Fox-Fordyce disease, we performed a computerized search of specimens in two dermatopathologic databases in Puerto Rico from the years 2000-2010. An additional specimen was donated by a dermatopathologist from an outside institution. Three cases were evaluated using hematoxylin-eosin-stained sections. The tip of an axillary lipoma excision specimen was used as the control tissue. Periodic acid-Schiff, colloidal iron, and immunoperoxidase staining for CD68 and c-kit (CD117) were performed in all specimens.

Results: We were able to verify traditionally described histological features such as infundibulum dilation, hyperkeratosis, plugging, acanthosis, and lymphohistiocytic infiltrate. Infundibular spongiosis was also common. A perifollicular foam cell infiltrate was the most distinct pathologic feature among our cases. The periodic acid-Schiff staining patterns suggested that the foam cell cytoplasm material might be similar in nature to the apocrine gland secretion content.

Conclusions: Our results confirmed that a perifollicular foam cell infiltrate is the most distinct histopathologic feature. In addition, findings suggest that the intracytoplasmic foam cell material may be similar in nature to the apocrine gland secretion.