Histopathologic and Immunohistochemical Assessment of Penile Carcinomas
Mark J Mentrikoski, Stephen Culp, Edward B Stelow, Henry F Frierson, Helen P Cathro. University of Virginia, Charlottesville, VA
Background: Despite an increased incidence in developing countries, penile carcinoma remains uncommon and relatively understudied in the United States. This study therefore examines the histologic and immunohistochemical features of penile carcinomas from a North American cohort in order to provide additional information about the malignancy.
Design: 61 penile squamous cell carcinomas from 57 patients were retrieved from the archives; 25 patients had metastatic disease. A tissue microarray including both primary and metastatic tumors was constructed. Cases were evaluated for pathologic stage, grade, histologic variant, perineural invasion (PNI), and lymphovascular space invasion (LVSI). Immunohistochemical stains for p16, p53, EGFR, and cyclin D1, as well as chromogenic in situ hybridization for high-risk HPV and Her2/neu were performed on all primary and metastatic tumors.
Results: 93% of cancers were T2 or T3. 47% were poorly differentiated, 21% were well-differentiated, and 32% were moderately differentiated; 72% were of usual-type histology, 10% were warty, 7% were basaloid, and 11% were other variants. PNI and LVSI were seen in 44% and 11% of cases, respectively. PNI alone was significantly associated with local groin metastasis (59.1% vs. 32.4%, p=0.048). p16 was overexpressed in 30% of cases, including almost all warty and basaloid variants, and significantly correlated with poorly differentiated tumors (p=0.031). High-risk HPV was detected in 25% of cases; all HPV positive tumors were p16 positive and the majority (67%) were associated with non-usual type histologies. p53 immunoreactivity, present in 35% of tumors, was inversely correlated with p16 positivity (p=0.001). Both p53 and cyclin D1 positivity were most commonly seen in usual variant cancers. EGFR overexpression occurred in 79% of cases, and was most often present in the usual variant (91%). Her2 overexpression was not detected in any tumor. Metastases consistently showed the same alterations as their corresponding primary tumors.
Conclusions: Similar to previous studies of penile carcinomas, the usual-type variant of squamous cell carcinoma is the most common. Perineural invasion is predictive of local metastasis. p53, cyclin D1, and EGFR are overexpressed most often in tumors showing usual-type histology. p16 overexpression was seen in almost one-third of all cases, and was strongly associated with basaloid and warty variants. As with studies of squamous cell carcinoma at other anatomic sites, p16 overexpression predicted high-risk HPV infection.
Category: Genitourinary (including renal tumors)
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 216, Tuesday Afternoon