Zoon balanitis: not a distinct clinicopathological entity?

Zoon balanitis (ZB) was originally described in the 1950s in patients with clinical features resembling erythroplasia of Queyrat, but with histology that demonstrated a plasma cell infiltrate without evidence of dysplasia. Subsequently, ZB has been extensively reported in the literature, reflecting widespread acknowledgement as an established distinct clinicopathological entity. However, its existence as such has been questioned and there have been suggestions in the literature that ZB represents either a non-specific irritant reaction pattern, or a part of the heterogenous clinicopathological complex of male genital lichen sclerosus (MGLSc). In this study, the entire historical literature of published cases of ZB was subject to review, to determine respectively whether clinical or histological features of MGLSc had been present and been overlooked. One hundred and one papers were reviewed. Seventy-five contained images purporting to be of ZB. Images that were deemed to be of inadequate quality or to present uninformative anatomical views were excluded. The images in 66 manuscripts were amenable to scrutiny; 98.5% of these images demonstrated clinical signs of MGLSc, such as adhesions, effacement of the coronal sulcus and the frenulum, tightening of the prepuce, constrictive posthitis, etiolation of the glans, lichenoid inflammation and sclerosis. These findings strongly suggest that ZB occurs in the vast majority of cases as a manifestation of MGLSc and that its recognition as a distinct clinicopathological entity should be questioned, if not discontinued.