Scrotal carcinoma is a very rare skin cancer. This carcinoma has historically been associated with exposure to environmental or industrial carcinogens and has only rarely been associated with human papillomavirus (HPV). To determine the etiological relation between HPV and scrotal cancer we performed a comprehensive evaluation of the HPV involvement by using different genotyping techniques at the DNA and RNA level, and accurately stablishing the location of HPV in the tumor cells. P16INK4a overexpression was studied to determine its relation with HPV positive neoplasias and p53 expression to determine if this biomarker was mutated in HPV negative neoplasias.
Six scrotal carcinomas have been collected from Spain (n=2), Australia (n=2) and Nigeria (n=2) with a median patient age of 60.5 years. FFPE specimens were sectioned by sandwich technique under strictly non-contamination conditions for histological diagnosis, whole tissue PCR analysis and laser capture microscopy-PCR (LCM-PCR). Sections were stained by haematoxylin and eosin, for p16INK4a and for p53. Independent pathologists evaluated histopathology and immunohistochemistry. HPV analyses on whole tissue sections was performed at the DNA level by SPF10-DEIA-LiPA25 (version 1), by MPTS 123 PCR-Luminex assay, by Beta HPV assay and Cutaneous Wart-Associated HPV; and at the RNA level by E6*I mRNA Reverse Transcription (RT)-PCR and luminex genotyping system. To evaluate DNA/RNA quality and PCR inhibition RNaseP/PhHV qPCR and transcript ubiquitin C system.
Squamous cell carcinoma was the only histological type identified. HPV genotyping analyses (DNA/RNA) on whole tissue sections reveal the single presence of HPV16 in three out of six cases. Subsequently, LCM-PCR analysis on these three positive cases confirmed the presence of HPV16 in tumor cells. P16INK4a was overexpressed on these three HPV16 positive cases and p53 was overexpressed (75%) in two out of three HPV negative tumors. From one of these three HPV positive patients metastatic biopsies were available and in all of them HPV16 presence was confirmed with the same methodology
HPV16 is mostly associated to mucosal malignant lesions and it has only very occasionally been associated with scrotal cancer. This is the first time that HPV16 has been shown to be definitively present in invasive neoplastic cells of cutaneous cancer from the scrotum. A decrease in scrotal cancer incidence was expected with improved occupational hygiene and the removal of chemical carcinogens. However, such tumors still occur infrequently due to HPV infection.