Penile warty mucoepidermoid carcinoma with features of stratified mucin‐producing intra‐epithelial lesion and invasive stratified mucin‐producing carcinoma

Aims Stratified mucin‐producing intra‐epithelial 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 ( HPV ) genotyping. The mucinous component was diffusely positive for cytokeratin 7 and largely negative for cytokeratin 5 and p63. Fluorescence in‐situ hybridisation did not detect rearrangement in the MAML 2 or EWSR 1 genes. The tumour was pathological stage pT 2, pN 1 ( 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 upon 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 intra‐epithelial neoplasia’.