Primary cutaneous mucinous carcinoma on the cheek arising from a probable precursor lesion of endocrine mucin－producing sweat gland carcinoma

Abstract

A 74－year－old man presented with a left cheek nodule. He had a surgical history of excision of the cheek lesion nine years previously, which was diagnosed as a benign neoplasm with sweat gland differentiation. Histopathologically, the nodule consisted of nests embedded in mucin pools, while immunohistochemically, the tumor cells were positive for cytokeratin 7 (CK7) and gross cystic disease fluid protein 15 (GCDFP－15) and negative for CK20. No lesions were observed in the other visceral organs. Based on a diagnosis of primary cutaneous mucinous carcinoma (PMC) with left parotid lymph node metastasis, he underwent a wide local excision and radical neck dissection. He received additional excision and radiation therapy for local recurrence 20 months later. We retrospectively reviewed specimens from past excisions. The tumor consisted of sweat gland－like epithelium and was positive for CK7 and GCDFP－15. The pre－existing lesion was diagnosed as endocrine mucin－producing sweat gland carcinoma, which most likely progressed to PMC. [Skin Cancer (Japan) 2019 ; 34 : 57－62]