2432 Incidental Diagnosis of Merkel Cell Carcinoma in a Liver Transplant Patient Admitted for Diverticulitis

Abstract

INTRODUCTION: Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine skin cancer. Most patients (80%) who develop MCC have been infected with a Merkel cell polyomavirus. Sun exposure, fair skin, and age are risk factors; however, it occurs most commonly in immunosuppressed patients, specifically organ transplant and HIV-infected patients. Though the exact mechanism is still unknown, it is thought thatimmunosuppression contributes to viral integration, mutagenesis, and carcinogenesis of the virus. CASE DESCRIPTION/METHODS: 75-year-old white male with a history of liver transplantation for NASH cirrhosis, maintained on mycophenolate and tacrolimus, was admitted to the hospital for diverticulitis. Lab results showed pancytopenia. CT abdomen showed acute diverticulitis, and a nonspecific soft tissue density near the porta hepatis encasing the common and proper hepatic arteries (Figure 1). A focused physical exam showed a large axillary mass (Figures 2 and 3). His diverticulitis improved with a course of broad-spectrum antibiotics. The mass was biopsied and positive for MCC, suggesting the lesion near the porta hepatis represented metastasis. The axillary mass was excised and he received local radiation therapy. He was unable to undergo chemotherapy due to poor performance status. Within 10 months of the diagnosis, the patient died. DISCUSSION: While MCC is most commonly associated with the long-term immunosuppression following solid-organ transplantation, its occurrence is also rising in older adults whose immune function naturally declines with time. The median onset of MCC is greater than 65 years of age, and occurs most often in white patients. The most common site of origin is the head and neck region, but it can arise anywhere in the body. The diagnosis of MCC can be challenging due to the innocuous appearance of the primary tumor. This case demonstrates the importance of understanding the potential sequela of immunosuppressive medications in organ transplant patients and performing regular and thorough physical exams in order to quickly detect and treat diseases like MCC.