Brown H A, Sawyer D M, Woo T
Department of Pathology and Laboratory Medicine/Faculty of Medicine, University of Calgary, Alberta, Canada.
Am J Dermatopathol. 2000 Feb;22(1):65-9. doi: 10.1097/00000372-200002000-00013.
Cutaneous Merkel cell carcinoma (MCC) typically involves the dermis. Less than 10% of MCC have epidermal involvement. Only one MCC confined exclusively to the epidermis has been previously reported but was not recognized until the lesion recurred with typical MCC in the dermis. We present a case of a wholly intraepidermal pagetoid MCC without dermal involvement in a 74-year-old man with a 2.0-cm solitary verrucous papule on the left index finger. The initial biopsy and complete excision specimens showed marked epidermal hyperplasia, focal prominent squamous cell atypia, and MCC with florid pagetoid spread through the epidermis. There was no evidence of tumor within the dermis. The pagetoid MCC tumor cells showed diffuse cytoplasmic staining with antibodies to cytokeratin 20, and negative staining for chromogranin, neurofilament, S-100, vimentin, HMB45, leukocyte common antigen, and CD3. The cell of origin of MCC is still debated. The existence of an entirely intraepidermal variant of MCC would lend support to the view that MCC is a neoplastic expression of Merkel cells in at least some cases. Dermal-based MCC is a high-grade primary cutaneous neoplasm, but MCC confined exclusively to the epidermis may have a better prognosis.
皮肤默克尔细胞癌（MCC）通常累及真皮。不到10%的MCC有表皮受累。此前仅报道过1例完全局限于表皮的MCC，但直到病变在真皮内复发为典型的MCC才被识别出来。我们报告1例74岁男性患者，其左示指有一个2.0 cm的孤立性疣状丘疹，为完全位于表皮内的派杰样MCC，无真皮受累。初次活检及完整切除标本显示明显的表皮增生、局灶性显著的鳞状细胞异型性，以及派杰样广泛播散至表皮的MCC。真皮内无肿瘤证据。派杰样MCC肿瘤细胞对细胞角蛋白20抗体呈弥漫性胞质染色，而嗜铬粒蛋白、神经丝、S-100、波形蛋白、HMB45、白细胞共同抗原和CD3均呈阴性染色。MCC的起源细胞仍存在争议。完全位于表皮内的MCC变体的存在将支持至少在某些情况下MCC是默克尔细胞的肿瘤性表达这一观点。基于真皮的MCC是一种高级别原发性皮肤肿瘤，但仅局限于表皮的MCC可能预后较好。
