Endocrine mucin-producing sweat gland carcinoma
EMPSGC; "endocrine mucin-producing sweat gland carcinoma" (Flieder et al., 1997); precursor of primary cutaneous mucinous carcinoma in many cases
Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare, low-grade adnexal carcinoma with eccrine and neuroendocrine differentiation that arises almost exclusively on the eyelids of older adults. It is morphologically and biologically the cutaneous analogue of solid papillary carcinoma of the breast, and is widely regarded as a precursor of primary cutaneous mucinous carcinoma — the two entities frequently co-exist within the same lesion. Despite alarming histology with invasion and atypia, the clinical course is indolent: regional and distant metastasis are exceptionally rare. Mohs micrographic surgery offers the best balance of cosmesis and complete clearance.
Clinical features
- Slow-growing, well-circumscribed, skin-coloured to pink, sometimes cystic dermal nodule.
- >90% on the eyelids — particularly the lower eyelid; less commonly cheek, forehead.
- Median age 65–75; F>M (slight).
- Often present for years; clinically misdiagnosed as cyst, BCC or chalazion.
- Differential: chalazion, sebaceous cyst, BCC, sebaceous carcinoma, primary cutaneous mucinous carcinoma, hidrocystoma.
Histology & molecular
- Multinodular dermal proliferation of solid, cribriform and papillary cell nests with intracystic mucin.
- Bland to mildly atypical cells with neuroendocrine features (salt-and-pepper chromatin).
- Foci of extracellular mucin pools — when prominent, lesion overlaps with primary cutaneous mucinous carcinoma.
- Immunohistochemistry:
- Neuroendocrine markers — synaptophysin, chromogranin A, CD56, INSM1 typically positive.
- Hormone receptors — ER and PR usually positive.
- CK7+, GCDFP-15+, GATA3+.
- Myoepithelial markers (p63, calponin) positive at the periphery — confirming in-situ component.
- Differential by histology: solid papillary carcinoma of the breast (mammary metastasis must be excluded clinically and radiologically), sebaceous carcinoma, BCC.
Management
- Mohs micrographic surgery — preferred given periorbital location and cosmesis; recurrence rate <10%.
- Wide local excision with 5–10 mm margins acceptable where Mohs unavailable.
- Eyelid reconstruction (Hughes, Tenzel, Cutler-Beard) per defect — see eyelid reconstruction atlas.
- Sentinel lymph node biopsy not routinely indicated — nodal metastasis is exceptionally rare.
- Adjuvant radiotherapy for incomplete margins or recurrent disease.
- If areas of true invasive mucinous carcinoma are present, manage as invasive disease per mucinous carcinoma of skin.
Prognosis
Excellent — regional and distant metastasis exceptionally rare. The principal long-term issue is local recurrence and progression to invasive mucinous carcinoma if the lesion is incompletely excised. Annual ophthalmology / dermatology follow-up is appropriate.
References
- Flieder A et al. Endocrine mucin-producing sweat gland carcinoma — a clinicopathologic, immunohistochemical and ultrastructural study. Am J Surg Pathol; 1997.
- Zembowicz A et al. Endocrine mucin-producing sweat gland carcinoma — twelve new cases. Am J Surg Pathol; 2005.
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