Abstract
Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is an under-recognized low-grade carcinoma with predilection to the eyelid. Clinically, they present as edema or slowly growing cysts. We present two cases and discuss their clinical and histopathologic features. A 70-year-old male presented for evaluation of a lesion on his right lower eyelid. A 69-year-old female had a cystic papule on the lower eyelid. Both lesions had been present for years and were slowly enlarging. Biopsies showed a well-circumscribed multi-nodular dermal based tumor with lobular growth pattern. Tumor cells were composed of lightly eosinophilic oval to polygonal epithelial cells with inconspicuous nucleoli and bland nuclei. Nuclei had diffusely stippled chromatin imparting a salt and pepper appearance. Occasional mitotic figures were present. Tumor cells were positive for cytokeratin 7, epithelial membrane antigen, estrogen and progesterone receptors, GCDFP-15, and synaptophysin. Extra- and intracytoplasmic mucin was identified by mucicarmine special stain. Myoepithelial cells were focally present, which were highlighted by p63. There are discrepancy reports in the literature regarding expression of myoepithelial cells in EMPSGC. It has been proposed that loss of staining for myoepithelial markers could be regarded as evidence of early invasion, and EMPSGC may be a precursor of some cutaneous mucinous carcinoma. EMPSGC has morphologic and immunohistochemical features similar to mammary solid papillary carcinoma/endocrine ductal carcinoma in-situ, which frequently coexists with invasive mucinous carcinoma. Due to histologic and immunohistochemical similarities of ductal breast carcinoma and EMPSGC, a comprehensive physical and radiologic study should be done to rule-out metastatic breast carcinoma before the diagnosis of EMPSGC is made. It is important for the dermatologists and dermatopathologists to be aware of this under-recognized entity for appropriate diagnosis and treatment.
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