Dermoscopic and reflectance confocal microscopy findings in extra-genital HPV16-associated pigmented squamous cell carcinoma in situ

Squamous cell carcinoma in situ (SCCIS) affecting the ano-genital area (also termed Bowenoid papulosis, BP) is mostly associated with high-risk strains of human papilloma virus (HPV) (1). Isolated HPV-associated SCCIS in the extra-genital area, without concomitant genital HPV infection, has been reported infrequently (2); such cases may present as pigmented papules or plaques, which may be difficult to differentiate from melanoma. We describe here the clinical and dermoscopic features of isolated HPV-associated pigmented SCCIS (termed extra-genital BP) in a small case series. We also describe the findings of reflectance confocal microscopy (RCM), a bedside imaging technique that is useful for differentiating keratinocytic from melanocytic neoplasms. We use histopathology and immunohistochemistry (IHC) to elucidate the tissue correlates of the RCM findings. Finally, we compare the dermoscopic and RCM findings of the present series with those observed in 2 cases of classic genital BP.