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 (2000-2013 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 12-78 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.

HPV-negative Penile Intraepithelial Neoplasia (PeIN) With Basaloid Features

“…Interestingly, all 5 lesions showed low proliferative index with Ki-67 staining, which is in keeping with the findings reported in HPV-associated precursors throughout the anogenital tract 29,30. To the best of our knowledge, this unusual histologic pattern of HPV-negative PeIN has not been reported in detail in PSCC, although a few dPeIN lesions with mixed basaloid and differentiated features have occasionally been mentioned in a few reports 17,22,23…”

“…29,30 To the best of our knowledge, this unusual histologic pattern of HPV-negative PeIN has not been reported in detail in PSCC, although a few dPeIN lesions with mixed basaloid and differentiated features have occasionally been mentioned in a few reports. 17,22,23 IHC stains were supportive of an HPV-independent oncogenic pathway involved in these cases. Expression of p16 was consistently negative in all 5 cases, both in the basaloid dPeIN and the associated PSCC.…”

“…29 , 30 To the best of our knowledge, this unusual histologic pattern of HPV-negative PeIN has not been reported in detail in PSCC, although a few dPeIN lesions with mixed basaloid and differentiated features have occasionally been mentioned in a few reports. 17 , 22 , 23 …”

“… 21 In the penis, a few studies have occasionally briefly mentioned PeIN lesions showing mixed differentiated and basaloid or differentiated and warty features. 17 , 22 , 23 However, this HSIL-like pattern of dPeIN has not been thoroughly characterized in terms of HPV testing and p16 and p53 IHC staining patterns. In this study, we aimed to describe, in a series of well-characterized HPV-independent PSCC (negative for HPV DNA and p16), the prevalence and the histologic features of dPeIN with HSIL-like morphology, a lesion that can be easily misdiagnosed as HPV-associated penile HSIL.…”

An overview of benign and premalignant lesions of the foreskin

“…In this extremely uncommon situation, a negative p16 and positive GATA3, CK7 and uroplakin-III or thrombomodulin would favour meatal involvement by neoplastic urothelium. 27 Bowenoid papulosis Bowenoid papulosis is a clinical term used to describe multiple papular lesions that develop on the anogenital region. On the penis, these lesions typically affect the shaft and foreskin.…”