Department of Pathology, Queen Elizabeth Hospital, Hong Kong SAR.
Ann Diagn Pathol. 2012 Oct;16(5):388-91. doi: 10.1016/j.anndiagpath.2011.01.011. Epub 2011 Jun 11.
Merkel cell carcinoma is an uncommon primary neuroendocrine neoplasm of the skin that may exhibit divergent differentiation. However, rhabdomyosarcomatous differentiation has only been rarely described and takes the form of isolated rhabdomyoblasts. We describe a case of cutaneous Merkel cell carcinoma with biphasic morphology imparted by discrete patches of embryonal rhabdomyosarcoma-like spindle cells alternating with islands of neuroendocrine small round cells, justifying a designation of "Merkel cell carcinosarcoma." The former component showed positive immunostaining for desmin and myogenin; and the later component, pan-cytokeratin, cytokeratin 20, synaptophysin, and chromogranin. The patient was an elderly man who presented with a temporal skin mass, and the biphasic morphology was evident in the recurrence and metastasis that developed 2 months after incomplete excision of the skin lesion.
默克尔细胞癌是一种罕见的皮肤原发性神经内分泌肿瘤，可能表现出不同的分化。然而，横纹肌肉瘤样分化仅被很少描述，并且表现为孤立的横纹肌母细胞。我们描述了一例皮肤默克尔细胞癌，其具有双相形态，由离散的胚胎横纹肌肉瘤样梭形细胞斑块与神经内分泌小圆细胞岛交替形成，这证明了“默克尔细胞癌肉瘤”的诊断。前者成分对 desmin 和 myogenin 免疫染色阳性；后者成分对 pan-cytokeratin、cytokeratin 20、synaptophysin 和 chromogranin 免疫染色阳性。患者为老年男性，表现为颞部皮肤肿块，在皮肤病变不完全切除 2 个月后出现的复发和转移中可见双相形态。
