Characterization of different clinical presentation of Merkel cell carcinomas and their potential prognostic implications

Background: Recent studies analyzed the impact of Merkel cell polyomavirus (MCPyV) on the prognosis of Merkel cell carcinoma (MCC) patients. No data on specific morphological clinical differences of MCPyV+ or MCPyV- are currently available neither on the possible prognostic implication of different clinical presentation of MCC.

Objectives: 1) to describe clinicopathological characteristics of MCC patients and the prevalence of MCPyV infection in an Italian cohort of patients; 2) to define possible differences in clinicopathological and prognostic features among MCPyV+ and MCPyV- MCCs.

Methods: Retrospective, multicenter, cohort study conducted in two Italian tertiary referral centers. MCPyV presence was detected by immunohistochemistry (IHC) and PCR with two different primers amplifying VP1 (VP1-PCR) and LT viral region (LT-PCR). Clinicopathological features were compared between MCPyV+ and MCPyV- tumors and between red exophytic nodules and subcutaneous cyst-like MCCs.

Results: 62 MCCs were included, presenting as red exophytic nodules (69.3%) or with a subcutaneous cyst-like appearance (19.3%); MCPyV was detected in 40.3% of cases by IHC, 56.4% by VP1-PCR and 79% by LT-PCR. No correlation was found between clinical morphology and viral status. Mortality rate was 40.8% for MCPyV- and 23.1% for MCPyV+ (p-value 0.239) and 69.8% for red nodules and 25% for cyst-like lesions (p-value 0.005). By multivariable analysis, age at diagnosis, ki67 and treatment with surgery/radiotherapy remained the only factors significantly affecting the OS.

Conclusions: This study highlights the potential impact of clinical morphology of MCCs on prognosis. Subcutaneous cyst-like morphology may provide a survival benefit to the patients, regardless the presence of MCPyV.