Battistella Maxime, Durand Luc, Jouary Thomas, Peltre Bernard, Cribier Bernard
Department of Pathology, APHP Hôpital Saint Louis, Université Paris 7, Paris.
Am J Dermatopathol. 2011 Jun;33(4):383-7. doi: 10.1097/DAD.0b013e3181e3ceb9.
Merkel cell (primary cutaneous neuroendocrine) carcinoma is a rare neoplasm of the skin. Its occurrence has been reported in association with other cutaneous neoplasms (Bowen disease, squamous cell carcinoma) in cases regarded as collision tumors. It has recently been described in association with cysts of the follicle apparatus. We present a unique case of rapidly growing nodular tumor on the left forearm of an 84-year-old woman, which proved to be a Merkel cell carcinoma located within a cystic trichoblastoma. The malignant component located in the center of the lesion had typical histopathological and immunohistochemical features of Merkel cell carcinoma. It was surrounded by an epithelial proliferation, made of K17-positive basaloid cells, whose aspects where those of trichoblastoma in a retiform pattern. Both lesions were intertwined, suggesting that the Merkel cell carcinoma had developed within a previously existing trichoblastoma and that it derived from the follicular Merkel cells present in the trichoblastoma. The unique features of this case, together with the reported cases of Merkel cell carcinoma arising within follicular lesions, and the fact that numerous Merkel cells are normally localized in the adult hair follicle, further support the hypothesis of a histogenetic link between normal follicular Merkel cells and Merkel cell carcinoma.
默克尔细胞（原发性皮肤神经内分泌）癌是一种罕见的皮肤肿瘤。在被视为碰撞瘤的病例中，其发生与其他皮肤肿瘤（鲍恩病、鳞状细胞癌）有关。最近有报道称其与毛囊器官囊肿有关。我们报告了一例独特的病例，一名84岁女性左前臂出现快速生长的结节性肿瘤，经证实是位于囊性毛母细胞瘤内的默克尔细胞癌。位于病变中心的恶性成分具有默克尔细胞癌典型的组织病理学和免疫组化特征。它被由K17阳性基底样细胞组成的上皮增生所包围，其形态呈网状毛母细胞瘤的形态。两种病变相互交织，提示默克尔细胞癌在先前存在的毛母细胞瘤内发生，且起源于毛母细胞瘤中存在的毛囊默克尔细胞。该病例的独特特征，以及报道的在毛囊病变内发生默克尔细胞癌的病例，以及大量默克尔细胞通常定位于成人毛囊这一事实，进一步支持了正常毛囊默克尔细胞与默克尔细胞癌之间存在组织发生学联系的假说。
