Penile warty-mucoepidermoid carcinoma with features of stratified mucin-producing intraepithelial lesion and invasive stratified mucin-producing carcinoma

Abstract

Aims

Stratified mucin-producing intraepithelial lesion (SMILE) and invasive stratified mucin-producing carcinoma (ISMC) are recently described cervical and penile lesions. We report an unusual case of mixed variant of penile squamous cell carcinomas with warty, usual and mucoepidermoid SMILE/ISMC features.

Methods and results

A 62-year-old Japanese man had a glans penis lesion of one and a half years duration, suggesting malignancy. Partial penectomy and left inguinal lymphadenectomy were performed. Pathological evaluation revealed a mixed squamous cell carcinoma with warty, mucinous and usual features. The mucinous component resembled mucoepidermoid carcinoma (MEC) and SMILE/ISMC. Glandular differentiation was absent. All the diverse tumour components were negative for p16 which was confirmed by negative human papillomavirus genotyping. The mucinous component was diffusely positive for cytokeratin 7 and largely negative for cytokeratin 5 and p63. Fluorescent in situ hybridization did not detect rearrangement in the MAML2 or EWSR1 genes. The tumour was pathologic stage pT2, pN1 (AJCC prognostic stage group IIIA) and was disease-free 26 months after surgery.

Conclusions

The lack of glands in the mucinous areas suggested that MEC should be separated from adenosquamous carcinoma (ASC) Penile SMILE/ISMC may occur without dependence on HPV status. Further studies will be necessary to determine the pathogenesis and definition of penile SMILE/ISMC, the presence of true MEC arising from the glans penis, and the clinicopathological differences of penile ASC, MEC, and SMILE/ISMC. Herein, we refer to the SMILE-like penile lesion as "mucinous penile intraepithelial neoplasia".

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