Histologic Findings
The proposed apocrine origin of Fox-Fordyce disease was based on the finding of a keratin plug in the follicular infundibulum that occluded the apocrine acrosyringium. Reports also include a rupture of the apocrine duct and a resulting spongiotic inflammation. Plasma cells may be noted, and the deeper apocrine duct may be dilated with sialomucin. The dermis may show fibrosis and chronic inflammation. These latter findings depend on the condition's chronicity.
Transverse sectioning may allow for a more accurate diagnosis of Fox-Fordyce disease. Bormate et al contend that perifollicular xanthomatosis (foam cells) is a specific, relatively consistent, and distinct histologic feature in 7 cases. [13] Perifollicular xanthomatosis may result in a histologic misdiagnosis of planar xanthoma due to sectioning error (author). Apocrine acini dilation may be another helpful nonspecific histologic finding. [14]
