Original ArticlesAn Update on Endocrine Mucin-producing Sweat Gland Carcinoma Clinicopathologic Study of 63 Cases and Comparative AnalysisAgni, Meghana MD*; Raven, Meisha L. DO†; Bowen, Randy C. MD‡; Laver, Nora V. MD§; Chevez-Barrios, Patricia MD∥; Milman, Tatyana MD¶; Eberhart, Charles G. MD, PhD#; Couch, Steven MD**; Bennett, Daniel D. MD††; Albert, Daniel M. MD, MS‡‡; Hogan, R. Nick MD, PhD§§; Phelps, Paul O. MD∥∥; Stiefel, Hillary MD‡‡; Mancera, Norberto MD¶¶; Hyrcza, Martin MD, PhD##; Wang, Ami MD***; Burris, Christopher K.H. MD†††; Steele, Eric A. MD‡‡; Campbell, Ashley A. MD#; Potter, Heather D. MD†; Lucarelli, Mark J. MD†Author Information *Department of Pathology, University of Chicago Medicine, Chicago ∥∥Division of Ophthalmology, NorthShore University, Health System, Glenview, IL Departments of †Ophthalmology and Visual Sciences ††Dermatology, University of Wisconsin School of Medicine and Public Health (SMPH), Madison ¶¶Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, WI ‡Cole Eye Institute and Cleveland Clinic, Cleveland, OH §Ocular Pathology Laboratory, Department of Ophthalmology & Pathology and Laboratory Medicine, Tufts Medical Center and Tufts University School of Medicine, Boston, MA ∥Department of Pathology and Genomic Medicine, Houston Methodist Hospital, Houston §§Departments of Ophthalmology & Pathology, University of Texas Southwestern, Dallas, TX ¶Ocular Pathology Service, Wills Eye Hospital at Thomas Jefferson University, Philadelphia, PA #Division of Neuropathology & Ophthalmic Pathology, Johns Hopkins Hospital, Baltimore, MD **Department of Ophthalmology and Visual Sciences, Washington University, St. Louis, MO ‡‡Casey Eye Institute, Oregon Health & Science University, Portland, OR †††Ovation Eye Institute, Washington, DC ##Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB ***Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada Conflicts of Interest and Source of Funding: Funding for this research was provided by NIH Core Grant P30 EY016665 and an Unrestricted Grant from Research to Prevent Blindness, Inc. to the University of Wisconsin Department of Ophthalmology and Visual Sciences. The authors have disclosed that they have no significant relationships with or financial interest in any commercial companies pertaining to this article. Correspondence: Meghana Agni, MD, Department of Pathology, University of Chicago Medicine, 5841 S. Maryland Ave. MC 6101, Rm. P-615, Chicago, IL 60637-1470 (e-mail: [email protected]). The American Journal of Surgical Pathology: August 2020 - Volume 44 - Issue 8 - p 1005-1016 doi: 10.1097/PAS.0000000000001462 Buy SDC Metrics Abstract Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade adnexal neoplasm with predilection for the periorbital skin of older women. Histologically and immunophenotypically, EMPSGC is analogous to another neoplasm with neuroendocrine differentiation, solid papillary carcinoma of the breast. Both lesions are spatially associated with neuroendocrine mucinous adenocarcinomas of the skin and breast, respectively. EMPSGC is ostensibly a precursor of neuroendocrine-type mucinous sweat gland adenocarcinoma (MSC), a lesion of uncertain prognosis. Non-neuroendocrine MSC has been deemed locally aggressive with metastatic potential, and previous works speculated that EMPSGC-associated (neuroendocrine-type) MSC had similar recurrence and metastatic potential with implications for patient follow-up. Only 96 cases of EMPSGC have been reported (12 cases in the largest case series). Herein, we present 63 cases diagnosed as “EMPSGC” in comparison with aggregated results from known published EMPSGC cases. We aim to clarify the clinicopathologic features and prognostic significance of the neuroendocrine differentiation of EMPSGC and its associated adenocarcinoma and to determine the nosological relevance of EMPSGC association in the spectrum of MSC histopathogenesis. Results established an overall female predominance (66.7%) and average presenting age of 64 years. EMPSGC lesions were associated with adjacent MSC in 33.3% of cases. The recurrence rate for neuroendocrine-type MSC was ~21%, less than the reported 30% for non-neuroendocrine MSC. There were no cases of metastasis. EMPSGC and neuroendocrine-type MSC are distinct entities with more indolent behavior than previously reported, supporting a favorable prognosis for patients. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.