Merkel's Cell Carcinoma in Organ Recipients

Abstract

In the general population Merkel's cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer. More than 600 cases have been reported. MCC seems to be common in transplant recipients, with 41 cases being reported to the Cincinnati Transplant Tumor Registry, and another 11 in the transplant literature. In the general population, it is a disease of older adults, with only 51% of cases occurring below the age of 50 years. In transplant patients, the mean age at diagnosis was 53 (range 33-78) years, and 29% of recipients were <50 years old. The tumor appeared from 5 to 286 (mean 91.5) months after the transplant. Of 44 lesions that occurred in 41 patients, the distribution was similar to that seen in the general population, with 36% occurring on the head and neck, 32% on the upper extremities, 16% on the trunk, 9% at unknown sites, and 7% on the lower extremities. Twenty of the patients (49%) had 22 other malignancies, the great majority of which (91%) were other skin cancers. Treatment depended on the stage of the disease and included wide surgical excision, radical lymph node dissection, radiation therapy, and chemotherapy. In transplant patients, MCC probably proved to be more aggressive than in the general population in that 68% of patients developed lymph node metastases and 56% died of their malignancies. Furthermore, one third of surviving patients still have active cancers from which they may die. Also, follow-up of survivors has been relatively short, with a mean of only 18 (range 0-135) months.

Rationale For Immune-Based Therapies in Merkel Polyomavirus-Positive and -Negative Merkel Cell Carcinomas

“…While 90% of MCC patients do not have clinically apparent immune dysfunction, patients on immunosuppressive regimens following organ transplantation or with compromised cell-mediated immunity (such as those with chronic lymphocytic leukemia and HIV/AIDs) are 10-30-fold more likely to develop MCC and suffer a higher MCC-specific mortality rate than the general population [5,[31][32][33][34]. This suggests that impaired cellular immunity predisposes individuals to not only developing MCC, but also to poorly controlling their disease.…”

Radiation monotherapy as regional treatment for lymph node‐positive Merkel cell carcinoma

“…It is a disease that primarily afflicts white elderly individuals and is associated with ultraviolet exposure, immunosuppression, and a newly described Merkel cell polyomavirus. [1][2][3] The reported incidence of MCC has tripled in the past 20 years primarily due to increased detection through the development of immunohistochemical staining for cytokeratin-20, which is specific for MCC. In addition, increases in relevant risk factors (age >50 years, ultraviolet exposure, human immunodeficiency virus, solid organ transplantation) have likely resulted in true increases in the incidence of MCC.…”

Prevalence of Merkel cell polyomavirus in Merkel cell carcinoma

“…Although the estimated annual incidence of Merkel cell carcinoma in the United States is only about 470 cases a year, there has been a threefold increase of cases since 1986. 6 Interestingly, the incidence of Merkel cell carcinoma is significantly higher in populations with organ transplants, lymphoma, and reduced immunity; 7,8 patients with HIV have a relative risk for the tumor of 13.4 compared with the general population. 9 Merkel cell carcinoma was recently shown to harbor a novel polyomavirus aptly named the Merkel cell polyomavirus, in the majority of cases.…”