Definitive Radiation Therapy for Merkel Cell Carcinoma Misdiagnosed as a Metastatic Tumor: A Case Report

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine neoplasia. Surgical resection is the first-line therapeutic option, and radiation therapy is an alternative treatment for inoperable cases. Herein, we report a case of primary MCC (cT2N0M0, stage IIA) of the head and neck region. This case was misdiagnosed as a metastatic tumor and referred to the department of radiation oncology for palliative irradiation. Additional immunohistochemical analysis confirmed the diagnosis of MCC, and the tumor was treated with definitive radiation therapy (66 Gy in 33 fractions), leading to complete in-field control. This case indicates that even in patients with suspected metastatic tumors referred for palliative treatment, patient characteristics and pathology should be carefully examined to avoid missing potentially controllable primary tumors. In such cases, MCC, although rare, should be included in the differential diagnosis of head and neck lesions.

The frequency of Merkel cell polyomavirus in whole blood from immunocompetent and immunosuppressed patients with kidney disease and healthy donors

Merkel cell polyomavirus (MCPyV) is a rare, aggressive and related to human diseases in immunocompromised patients. MCPyV has been detected in skin neoplasms, various cancers, immunosuppressed patients and immunocompetent individuals. Several studies have confirmed the presence of MCPyV in patients with kidney dysfunction, such as kidney transplant (KTx) and long-term dialysis patients. The aims of this study were to quantify and compare the frequency of MCPyV in whole blood samples from immunocompetent and immunosuppressed patients and healthy blood donors and to compare MCPyV genotypes in a Korean population. DNA from Groups 1, 2, and 3 was screened for MCPyV using polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) with primer pairs targeting two regions of the large T-antigen. Thirteen of 122 whole-blood samples (12.7%) were positive for MCPyV. The virus was detected in the three groups of patients and healthy donors; specifically, in 5 of 30 (16.7%) KTx patients (Group 1), 6 of 52 (11.5%) dialysis patients (Group 2), and 4 of 40 (10%) healthy donors (Group 3). Low viral DNA loads 4.4-18 copies/μl were observed using qPCR DNA sequences from the two MCPyV-LT regions, which showed high homology with MCPyV sequences belonging to the TKS strain from Japan rather than the Chinese/European/North American strains. The MCPyV DNA was similarly amplified in whole blood from immunocompetent and immunosuppressed patients and healthy donors. This virus may be involved in establishing the persistence of infected peripheral leukocytes in the host, based on the incidence of detection of MCPyV DNA in blood samples from immunocompromised and immunocompetent subjects. This study is the first to identify a Korean MCPyV strain in whole-blood samples from Korean patients with kidney disease and healthy individuals.