Penile Basaloid Squamous Cell Carcinoma
Basaloid carcinoma (BC) is an aggressive tumor composed of a monotonous population of small-to medium-sized cells with basophilic cytoplasm resembling basal cells (Cubilla et al. 1998).
It accounts for 5–10% of penile carcinomas commonly arising in the glans, rarely in the foreskin. BC has a high incidence of nodal metastasis, with more than 50% of cases showing regional metastasis at presentation (Guimarães et al. 2009). The mortality rate due to systemic spread is very high (>60%), and particularly tumors deeply infiltrating the corpora cavernosa with a >10 mm diameter carry a bad prognosis.
Immunohistochemistry and Molecular Typing
High-Grade Usual-Type Squamous Cell Carcinoma (SCC)
Usual-type SCC shows pleomorphic cells with abundant keratinized cytoplasm, while BC shows uniform nests of small cells throughout the tumor and keratinization is confined to the central area.
Urothelial Urethral Carcinoma (UUC)
UCC most frequently occurs adjacent to CIS and papillary urothelial carcinoma in the urothelial mucosa, and absence of p16 immunostaining and positivity for GATA3 support the urothelial origin.
Small Cell Neuroendocrine Carcinoma
Neuroendocrine carcinoma, in particular metastasis of Merkel cell carcinoma, has organoid, ribbon/trabecular features that are absent in BC. Immunohistochemical staining for CK 20 and neuroendocrine markers is sometimes necessary for a definitive diagnosis.
References and Further Reading
- Chaux, A., Cubilla, A. L., Haffner, M. C., Lecksell, K. L., Sharma, R., Burnett, A. L., & Netto, G. J. (2014). Combining routine morphology, p16 (INK4a) immunohistochemistry, and in situ hybridization for the detection of human papillomavirus infection in penile carcinomas: A tissue microarray study using classifier performance analyses. Urologic Oncology, 32(2), 171–177.CrossRefGoogle Scholar
- Cubilla, A. L., Reuter, V. E., Gregoire, L., Ayala, G., Ocampos, S., Lancaster, W. D., & Fair, W. (1998). Basaloid squamous cell carcinoma: A distinctive human papilloma virus-related penile neoplasm: A report of 20 cases. The American Journal of Surgical Pathology, 22(6), 755–761.CrossRefGoogle Scholar
- Cubilla, A. L., Lloveras, B., Alejo, M., Clavero, O., Chaux, A., Kasamatsu, E., Velazquez, E. F., Lezcano, C., Monfulleda, N., Tous, S., Alemany, L., Klaustermeier, J., Muñoz, N., Quint, W., de Sanjose, S., & Bosch, F. X. (2010). The basaloid cell is the best tissue marker for human papillomavirus in invasive penile squamous cell carcinoma: A study of 202 cases from Paraguay. The American Journal of Surgical Pathology, 34(1), 104–114.CrossRefGoogle Scholar
- Cubilla, A. L., Lloveras, B., Alemany, L., Alejo, M., Vidal, A., Kasamatsu, E., Clavero, O., Alvarado-Cabrero, I., Lynch, C., Velasco-Alonso, J., Ferrera, A., Chaux, A., Klaustermeier, J., Quint, W., de Sanjosé, S., Muñoz, N., & Bosch, F. X. (2012). Basaloid squamous cell carcinoma of the penis with papillary features: A clinicopathologic study of 12 cases. The American Journal of Surgical Pathology, 36(6), 869–875.CrossRefGoogle Scholar