The variable morphological spectrum of penile basaloid carcinomas: differential diagnosis, prognostic factors and outcome report in 27 cases classified as classic and mixed variants

ABSTRACT

Background: Basaloid carcinomas of the penis, HPV-related tumors, are morphologically less homogenous than originally thought. The study objective was to evaluate the prognostic influence of the basaloid pattern in mixed tumors. Methods: We studied 154 Mexican patients from the Hospital de Oncología, CMN, Mexico City (2000­2013) and found 27 with basaloid features in at least 20% of the sections classified as classic basaloid (8 cases), warty-basaloid (7), papillary-basaloid (5) and usual-basaloid squamous cell carcinomas (7). We evaluated patients' age, site and size of tumor, histological classification, grade, thickness, anatomical level, vascular and perineural invasion, prognostic index score and node involvement. Penile intraepithelial neoplasia in adjacent epithelia was documented. Follow up ranged from 12­78 months. Statistical methods were Fisher's exact test and Kruskal-Wallis test. Kaplan-Meier method and log-rank test were used for survival analysis. The cutoff for statistical significance was p <0.05. Results: There were not clinical differences. Microscopically types were distinctive and easy to separate. Usual-basaloid squamous cell carcinomas were smaller, thinner and rarely invaded corpora cavernosa, with a low prognostic index score. Classic basaloid, warty-basaloid and papillary-basaloid carcinomas had higher rates of vascular and perineural invasion and higher prognostic index scores. These findings correlated with the rate of nodal metastasis. The majority of patients with classic and papillary-basaloid neoplasms died from systemic metastasis (87.5 and 80%) whereas only 1 patient with usual-basaloid carcinoma died of the disease (14%). Conclusions: Basaloid carcinomas are not a single entity but a spectrum of variable histological architectures mixed with those of classic basaloid tumors. Identification of mature squamous cells in a basaloid carcinoma may be important to recognize and report because patients with these tumors may carry a better prognosis (AU)