Microsatellitosis in Merkel cell carcinoma: a staging quandary

摘要

Merkel cell carcinoma（MCC） is a rare small cell cancer of the skin with a high rate of metastasis and mortality. Although microsatellite disease-disease deposits in close proximity to, yet discontinuous from, the site of the primary tumor and revealed only on pathological assessment-has been characterized as an adverse prognosticator in melanoma, its significance has not yet been established in MCC 【1】. We investigated the frequency of microsatellite disease in a 5-year cohort of patients with primary cutaneous MCC by reviewing pathology reports available from the Mass General Brigham electronic medical record and examined the real-world staging decisions made in these situations 【2】. Of 213 patients, only 6 cases （2.8%）were clearly described as featuring microsatellite disease at presentation（Table 1）。 Of these cases, four were upstaged to Stage llb disease in the absence of any further metastasis, whereas one patient with microsatellite disease was classified as"local"or"Stage I "disease. The cases displayed variability in the size, number, and depth of the microsatellites（Table 1）.