Visiting Physician, Department of Pathology, Massachusetts General Hospital, Boston, MA.
Assistant Professor of Pathology, Department of Pathomorphology and Oncological Cytology, Wroclaw Medical University, Wroclaw, Poland.
Am J Dermatopathol. 2020 Sep;42(9):629-640. doi: 10.1097/DAD.0000000000001548.
Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine carcinoma of unknown origin. We performed a retrospective histologic review of primary cutaneous MCCs diagnosed from 1997 to 2018 in several clinical institutions and literature review to determine the frequency of various unusual morphologic appearances of MCC. Of the 136 primary MCCs identified, intraepidermal carcinoma or epidermotropism was noted in 11/136 (8%) cases. An association with pilar cyst in 1/136 (0.7%) case, with actinic keratosis in 2/136 (1.5%) cases, with either invasive or in situ squamous cell carcinoma (SCC) in 14/136 (10%) cases, with poroma in 1/136 (0.7%), and with basal cell carcinoma in 1/136 (0.7%) case was noted. Trabecular pattern and rosettes were noted in 7/136 (5%) and 3/136 (2%) cases, respectively. There was one case of metastatic MCC in a lymph node with chronic lymphocytic leukemia and one rare case of metastatic MCC and SCC in a lymph node. Although uncommon, differentiation toward other cell lineage can be observed in both primary and metastatic MCCs. The tumor can assume a variety of histologic appearances including association with SCC, basal cell carcinoma, melanocytic neoplasm, and follicular cyst; as well as exhibit glandular, sarcomatous, and mesenchymal differentiation. This diversity of morphologic appearance of MCC reflects the complexity of its underlying pathogenesis.
默克尔细胞癌（Merkel cell carcinoma，MCC）是一种起源不明的罕见且高度侵袭性神经内分泌癌。我们对多个临床机构在 1997 年至 2018 年间诊断的原发性皮肤 MCC 进行了回顾性组织学复习，并进行了文献复习，以确定 MCC 各种不同形态表现的频率。在确定的 136 例原发性 MCC 中，11/136（8%）例可见表皮内癌或表皮亲润性。1/136（0.7%）例与毛囊肿有关，2/136（1.5%）例与光化性角化病有关，14/136（10%）例与侵袭性或原位鳞状细胞癌（squamous cell carcinoma，SCC）有关，1/136（0.7%）例与汗腺瘤有关，1/136（0.7%）例与基底细胞癌有关。7/136（5%）例可见小梁状模式，3/136（2%）例可见玫瑰花结样结构。有 1 例转移性 MCC 伴慢性淋巴细胞白血病淋巴结转移，1 例罕见的转移性 MCC 和 SCC 伴淋巴结转移。尽管不常见，但在原发性和转移性 MCC 中均可观察到向其他细胞谱系分化。肿瘤可呈现多种组织学表现，包括与 SCC、基底细胞癌、黑色素瘤和滤泡囊肿相关，以及表现为腺性、肉瘤样和间叶分化。MCC 形态表现的多样性反映了其潜在发病机制的复杂性。
