Dermoscopic and reflectance confocal microscopy findings in palisaded encapsulated neuroma (PEN): report of two histologically confirmed cases

These medical case reports discuss the reflectance confocal microscopy (RCM) features of palisaded encapsulated neuromas (PEN), a relatively uncommon benign neural tumor that predominantly manifests in middle-aged females, most notably on the facial cheek. These reports feature two middle-aged females who both presented with concern for progressively enlarging cheek papules. Dermoscopy revealed the presence of symmetrical, dome-shaped papules with arborizing blood vessels that were not in sharp focus. RCM images revealed a honeycomb pattern, replete with follicular openings and slight papillary dermal fibrosis. Horizontally oriented blood vessels and vellus hair follicles, as well as prominent vellus hair bulbs were noted. The findings were initially perplexing and collectively raised the possibility of a skin adnexal neoplasm. However, subsequent biopsy confirmed a diagnosis of PEN in both cases. In retrospect, the neoplastic cells were beyond the imaging depths of RCM but the observed changes, including alterations in hair follicles on confocal microscopy, were likely due to pressure from the underlying tumor. Consideration of these features aids in diagnosing this unique yet benign neoplasm.