Endocrine mucin-producing sweat gland carcinoma (EMPSGC) and primary cutaneous mucinous carcinoma (PCMC) are both uncommon low-grade cutaneous adnexal tumors with predilection for the eyelids of elderly women. Their clinical appearance is nonspecific, typically presenting as a slowly growing poorly circumscribed papule, nodule, plaque, or swelling. Histological features of EMPSGC include a lobulated dermal neoplasm with bland cytology and an invasive mucinous component in up to half of the cases. PCMC exhibits tumor nests suspended in abundant pools of mucin with focal strands or nests of tumor cells infiltrating the dermis. Because of their rarity and banal cytological features, both entities pose a risk for misdiagnosis with other benign/malignant cutaneous adnexal neoplasms. Histomorphological features can suggest a diagnosis of EMPSGC or PCMC, but immunohistochemistry is necessary for confirmation. A review of the literature showed variable results of antigens present in EMPSGC, and many of the positive markers only show sparse or focal immunoreactivity of tumor cells. As a result, diffusely positive markers play a crucial role in identification of these tumors, particularly with initial superficial biopsies. We present 9 cases of EMPSGC and 5 cases of PCMC with strong and diffuse immunoreactivity to renal cell carcinoma antigen. This novel finding can be useful in the diagnosis of EMPSGC and PCMC in combination with other known positive markers to differentiate them from other cutaneous neoplasms. In addition, it provides further evidence that EMPSGC could be a precursor lesion to PCMC with both existing on a spectrum.
*University of Central Florida College of Medicine, Orlando, FL;
†Microdiagnostics Ltd, Thessaloniki, Greece;
‡Laboratory of Molecular Oncology, Hellenic Foundation for Cancer Research, Thessaloniki, Greece;
§Department of Cosmetic Science, Chia Nan University of Pharmacy and Science, Tainan, Taiwan;
¶Department of Pathology, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi, Taiwan;
║PathWest Laboratory Medicine, QEII Medical Centre, Nedlands, Western Australia, Australia;
**Southeastern Pathology Associates, SEPA Labs, Brunswick, GA;
††Department of Surgical Pathology, Changhua Christian Hospital, Changhua, Taiwan;
‡‡School of Medicine, Chung Shan Medical University, Taichung, Taiwan;
§§Mid Florida Dermatology and Plastic Surgery, Orlando, FL;
¶¶Consultant Pathologist Royal Cornwall Hospital and Plymouth Hospitals NHS Trust, Cornwall, United Kingdom;
║║Lately, Department of Surgical Pathology, Brigham and Women's Hospital, Boston, MA; and
***Mid Florida Pathology, Eustis, FL.
Correspondence: Carlos A. Cerruto, MD, FCAP, 1923 Lake Markham Preserve Trail, Sanford, FL 32771 (e-mail: firstname.lastname@example.org).