Frequent Detection of Merkel Cell Polyoma Virus in Cutaneous Basal Cell Carcinoma
A Andea, R Patel, P DeVilliers, S Ponnazhagan, S Kumar, G Siegal. University of Alabama at Birmingham, Birmingham, AL
Background: Polyomaviruses are frequently associated with malignancies in their hosts. Recently, a novel polyoma virus, named Merkel cell polyomavirus (MCV) was identified integrated to the genome of Merkel cell carcinoma (MCC) suggesting a role in its pathogenesis. Basal cell carcinoma (BCC) is the most common cutaneous neoplasm, characterized by basaloid cells with hyperchromatic nuclei and high nuclear to cytoplasmic ratio. We have observed that some BCC tumors show nuclear molding, finely granular chromatin pattern, high mitotic activity and expression of chromogranin, features that partially overlap with MCC however, in contrast to MCC are negative for CK20. In this study we evaluated the presence of MCV in a selected group of BCCs exhibiting morphologic or immunohistochemical neuroendocrine (NE) features.
Design: From our clinical database we selected 12 BCC cases that were deemed to exhibit NE morphology, and/ or expressed chromogranin. Following DNA extraction, we performed PCR using 2 prime pairs amplifying sequences within the T antigen of MCV. The identity of PCR products was confirmed by agarose gel electrophoresis. In addition, the selected cases as well as a control group of 44 BCC cases were evaluated for mitotic index / mm2, presence of necrosis, ulceration, apoptosis, squamous differentiation and peripheral palisading.
Results: All analyzed cases were negative for synaptophysin and CK20 ruling out MCC. Overall we were able to detect MCV amplicons in 9/12 analyzed tumors (75%). MCV positive cases compared to the rest of the cohort demonstrated a higher mitotic index (15 vs. 7 mitoses/ mm2, p=0.01), increase incidence of necrosis (37.5% vs. 12.5%, p=0.07), higher frequency of prominent apoptosis (50% vs. 12.5%, p=0.01) and less peripheral palisading (37.5% vs. 73%, p=0.04).
Conclusions: We have successfully identified the presence of MCV sequences in 75% of a subset of BCC tumors characterized by NE morphology and chromogranin expression. Our data shows that MCV is not specific for MCC tumors as initially described. MCV positive BCCs are characterized by higher mitotic rates, apoptosis, necrosis and lack of peripheral palisading. It is possible that MCV plays a role in the pathogenesis of both MCC and BCC tumors. Further studies are warranted to determine if the subset of MCV positive BCCs have a different biologic behavior.
Monday, March 22, 2010 1:45 PM
Platform Session: Section F, Monday Afternoon