HPyV6- and HPyV7-negative parakeratosis and dyskeratosis in squamous cell carcinoma in situ.

Background Peacock plumage refers to a stratum corneum with columns of parakeratosis and dyskeratosis composed of pink circles, some with retained nuclei, that resembles the patterning of peacock feathers. Such patterning has been described in association with a pruritic dermatosis with detectable human polyomaviruses 6 and 7 (HPyV6 and HPyV7). Objective We observed a similar pattern of peacock plumage in squamous cell carcinoma in situ (SCCis). Methods These lesions were tested for evidence of HPyV6 and HPyV7 using RNA in situ hybridization (RNA ISH). Cases were also stained with immunohistochemical antibodies directed against human papillomavirus (HPV) and the SV40 polyomavirus. Results No staining of the peacock plumage was evident using RNA ISH probes specific for HPyV6 and HPyV7 or anti-HPV and anti-SV40 immunohistochemical antibodies. Conclusions While the pattern of peacock plumage in these cases has some resemblance to that described in HPyV6- and HPyV7- associated pruritic dermatosis, the current cases did not have detectable HPyV or HPV using a combination of HPyV6- and HPyV7- specific RNA ISH probes and anti-HPV and anti-SV40 immunohistochemical stains. Further study of these cases may allow for a better understanding of peacock plumage in keratinocytic neoplasms. This article is protected by copyright. All rights reserved.