Histology of lichen nitidus

Scanning power view of lichen nitidus identifies a focal dermal inflammatory infiltrate enclosed within collarettes of epidermal acanthosis (Figures 1 and 2). Focal erosion of the epidermis in figure 1 indicates excoriation. Higher power view identifies a well circumscribed lymphohistiocytic infiltrate with multinucleated giant cells (Figures 3 and 4).

Figure 1

Figure 2

Figure 3

Figure 4

Differential diagnosis of lichen nitidus

Micropapular sarcoidosis: The inflammatory infiltrate is also seen focally within the papillary dermis, but is predominantly histiocytic forming non caseating epithelioid granulomas.

Lichen scrofulosorum: The non caseating granulomas are typically centred on the hair follicles or sweat ducts.

Papular granuloma annulare: Shows localized changes, but otherwise retains the typical infiltrate and collagen changes of granuloma annulare.