Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston, Texas, USA.
J Cutan Pathol. 2022 Sep;49(9):787-790. doi: 10.1111/cup.14282. Epub 2022 Jul 5.
Merkel cell carcinoma (MCC) is an aggressive, highly metastatic, cutaneous neuroendocrine malignancy with poor prognosis. Here, we describe a MCC excision specimen with a rare case of tumor-associated amyloid deposition in the absence of residual tumor cells. A 72-year-old man presented with a lesion of 5-6 months' duration on his left elbow, clinically thought to be a ganglion cyst. The biopsy specimen revealed a Stage IIA MCC with classic histomorphologic and immunophenotypic findings, with tumor extending to the tissue edges. The patient underwent wide local excision with negative margins and a negative sentinel lymph node biopsy. Although the patient did not receive any presurgical chemotherapy, immunotherapy, or targeted therapy, the re-excision specimen showed only amphophilic, feathery deposits that were salmon-pink with Congo red stain and further confirmed as amyloid by electron microscopy; there were no residual carcinoma cells. Amyloid deposition in MCC has been described in rare case reports. Our case was extraordinary in that there was only amyloid deposition and an associated granulomatous reaction, without identifiable MCC cells. This case demonstrates that amyloid deposition may be evidence of a prior MCC at the site of a prior procedure and may warrant careful evaluation for residual MCC.
默克尔细胞癌（Merkel cell carcinoma，MCC）是一种侵袭性、高度转移性的皮肤神经内分泌恶性肿瘤，预后不良。在此，我们描述了一例罕见的 MCC 切除标本，其中存在肿瘤相关淀粉样物质沉积，而无残留肿瘤细胞。一名 72 岁男性，因左肘部 5-6 个月的病变就诊，临床考虑为腱鞘囊肿。活检标本显示为 IIA 期 MCC，具有典型的组织形态学和免疫表型特征，肿瘤延伸至组织边缘。患者接受了广泛的局部切除，切缘阴性，前哨淋巴结活检阴性。尽管患者未接受任何术前化疗、免疫治疗或靶向治疗，但再次切除的标本仅显示嗜酸性、羽毛状沉积物，刚果红染色呈三文鱼粉红色，进一步通过电子显微镜证实为淀粉样物质；无残留的癌细。MCC 中淀粉样物质沉积已有罕见病例报告。我们的病例特别之处在于，仅有淀粉样物质沉积和相关的肉芽肿反应，而无可识别的 MCC 细胞。该病例表明，淀粉样物质沉积可能是先前手术部位存在 MCC 的证据，可能需要仔细评估是否存在残留的 MCC。
