Endocrine Mucin-Producing Sweat Gland Carcinoma: Case Presentation with a Comprehensive Review of the Literature

Abstract

(1) Background: Endocrine Mucin-Producing Sweat Gland Carcinoma (EMPSGC) is a rare, low-grade, neuroendocrine-differentiated, cutaneous adnexal tumor, officially recognized by the World Health Organization (WHO) Skin Tumors Classification in 2018 as a separate entity and homologue of endocrine ductal carcinoma in situ (eDCIS)/solid papillary carcinoma of the breast. Although it is more frequent in the female sex, between 60 and 70 years old, in the peri-orbital region, EMPSGC has also been described in the male sex, in subjects under 60 and over 80, and in extra-eyelid localizations (cheek, temple, scalp), but also in extra-facial localizations (chest and scrotum). (2) Methods: We present the clinical case of a 71-year-old woman with an undated lesion of the scalp, which presented as a nodule, skin-colored, and 2.5 cm in maximum diameter. We also conduct a comprehensive literature review from 1997 to the end of 2022, consulting PubMed, Scopus, Web of Science (WoS), and Google Scholar using the following keywords: “Endocrine mucin-producing sweat gland carcinoma” and/or “EMPSGC” and/or “skin” and “cutaneous neoplasms”. In addition, we followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 253 patients were recorded; 146 were females (57.7%) and 107 were males (42.2%). The vast majority of the lesions were in the eyelids (peri-ocular region), and only a minority of cases involved the cheeks, supra-auricular, retro-auricular, and occipital region, with very rare cases in the scalp, to which the present is also added. (4) Conclusions: The morphological and immunophenotypical features are essential both for the correct diagnosis and to be able to classify this lesion among the corresponding eDCIS/solid papillary carcinoma of the breast, with neuroendocrine differentiation. Recent papers have attempted to shed light on the molecular features of EMPSGC, and much remains to be conducted in the attempt to subtype the molecular profiles of these entities. Future studies with large case series, and especially with molecular biology techniques, will be needed to further add information about EMPSGC and its relationship in the PCMC spectrum.

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). 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.…”

“…The solid areas can also show rosette-like structures and focal cribriform architecture with apical snouts. It also has an inconspicuous and discontinuous myoepithelial cell layer surrounding lesional cells [2,3,7]. Cytological features of EMPSGC are not frequently described but show small to medium, round, monomorphic cells with neuroendocrine features such as finely granular or stippled nuclei and small or inconspicuous nucleoli in a background of minimal extracellular mucin [2,3,15].…”

“…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].…”