Human papilloma virus infection and mismatch repair protein expression in sebaceous neoplasms of the genital area.

AIMS: This study aimed to investigate the clinical and histopathological features of sebaceous tumours of the genital area and their association with human papilloma virus (HPV) infection and mismatch repair (MMR) protein deficiency.

METHODS AND

RESULTS

Ethical approval was obtained, haematoxylin and eosin (H&E)-stained sections were reviewed, and immunohistochemistry (IHC) for p16, p53, mismatch repair proteins and HPV RNA-in-situ hybridization or HPV genotyping were performed. Clinical follow-up was retrieved from patient records. Six tumours presented in adulthood (median: 69; range: 48-73 years; M:F = 2:1) and were located on the penis, mons pubis and labia majora (median size 1.3 cm). There were four sebaceous carcinomas, one sebaceoma and one sebaceous adenoma. Three of four sebaceous carcinomas showing an overlying in-situ component were positive for high-risk HPV-ISH or subtypes, p16 block positive and p53 wild-type by IHC. The sebaceous adenoma showed loss of mismatch repair proteins and was associated with Muir-Torre syndrome (MTS), while all remaining tumours showed intact MMR protein staining, were negative for HPV, and p16 and p53 wildtype by IHC. The patient with MTS died of oesophageal adenocarcinoma; all other patients were alive without recurrences (median follow-up: 16 months, range 7-60 months).

CONCLUSIONS

In conclusion, the study emphasizes a pathogenetic role of HPV in genital sebaceous carcinomas that typically present with an in-situ component.