Cytological findings in a case of endocrine mucin‐producing sweat gland carcinoma with metastasis to salivary glands

Abstract

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade skin adnexal neoplasm. It usually affects elderly patients, is more frequently observed in women, and has a predilection for the periorbital skin. It shares the same histological and immunohistochemical characteristics as solid papillary carcinoma (SPC) of the breast. 1 Local recurrences are common in EMPSGC, but metastases have not been reported until recently; 2-4 to date, only three cases have been reported, all of which involved ipsilateral parotid glands. Fine-needle aspiration cytology in these cases is difficult and is not usually performed. Herein, we report a case of eyelid EMPSGC metastatic to the contralateral eyelid and multiple salivary glands 8 years after the primary diagnosis.

Metastatic Endocrine Mucin-Producing Sweat Gland Carcinoma to the Lung: A Case Report

“…Endocrine mucin-producing sweat gland carcinoma was previously believed to be a low-grade neuroendocrine neoplasm with an indolent clinical course and a low rate of recurrence (<10%) following excision [2,3,5,12]. There have now been seven reported cases since 2020 of metastases, including this case, with the majority metastasizing to the parotid gland and none metastasizing to the lungs [3,7,8]. It is important to differentiate this lesion from mucinous carcinoma and breast solid papillary carcinoma with neuroendocrine differentiation (SPCND).…”

“…It is important to differentiate this lesion from mucinous carcinoma and breast solid papillary carcinoma with neuroendocrine differentiation (SPCND). Mucinous carcinoma is differentiated due to its small clusters of cells with cribriform or tubular structures in large pools of extracellular mucin, whereas metastatic SPCND shows similar features and an immunohistochemical profile [2,3,13]. Although classically thought of as having more than 90% extracellular mucin, neuroendocrine and non-neuroendocrine mucinous carcinoma is now well known to exist in either pure form (>90%) or in a mixed pattern, which can lead to diagnostic confusion if the mucinous component is not properly sampled, as its presence, even in mixed form, should classify the lesion as a mucinous carcinoma [12,14,15].…”

“…EMPSGC is known to be a well-circumscribed, nodular, and multilobulated lesion with both solid and cystic areas and minimal intracellular and extracellular mucin [2,3]. The solid areas can also show rosette-like structures and focal cribriform architecture with apical snouts.…”

“…Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare low-grade cutaneous neuroendocrine neoplasm believed to be of sweat gland origin, the cutaneous analogue to solid papillary adenocarcinoma of the breast, and a potential precursor to mucinous adenocarcinoma of the skin [1][2][3]. This entity was first described in 1997 [4], and to date there have only been just over 110 cases reported, with a predilection for females in their sixth to seventh decades of life and arising mainly in the periorbital skin [2,3,5]. The current suggested treatment is surgical excision alone [6].…”

“…The current suggested treatment is surgical excision alone [6]. Prior to 2020, this entity was believed to be non-metastasizing, and since then there have only been six reported cases of metastatic disease [3,[7][8][9][10][11], primarily to the parotid gland, with one also showing metastases to a rib and one with more systemic involvement. All cases have occurred after a prolonged clinical interval.…”