Apocrine carcinoma
Primary cutaneous apocrine adenocarcinoma; apocrine sweat-gland carcinoma
Apocrine carcinoma is a rare malignant adnexal tumour with apocrine differentiation, arising from sweat glands in their typical apocrine distribution — axilla, anogenital area (vulva, scrotum, perineum), areola and eyelid (the modified apocrine glands of Moll). It typically presents in middle-aged or elderly adults as a slowly enlarging dermal/subcutaneous nodule that may ulcerate. Despite its indolent presentation, regional nodal metastasis is common (reported up to ~40% in small series) and it carries substantial distant metastatic potential. Hormone-receptor (oestrogen, progesterone, androgen) positivity is common, opening adjuvant hormonal options. Wide local excision with sentinel-lymph-node biopsy is the cornerstone.
Clinical features
- Solitary firm, slowly enlarging, often skin-coloured to red-violaceous nodule.
- Predilection for apocrine-rich sites: axilla (~50%), anogenital, eyelid (Moll's gland of eyelid), scalp, areola.
- Median age 60–70; M:F roughly equal.
- Often present for years with delayed diagnosis; may ulcerate, bleed or fix to deeper tissues.
- Differential: epidermal cyst, hidradenitis suppurativa abscess (axilla), Bartholin gland carcinoma (vulva), eccrine porocarcinoma, basal cell carcinoma.
Histology
- Tubular, papillary or solid pattern of pleomorphic cells with abundant eosinophilic cytoplasm.
- "Decapitation secretion" — apical cytoplasmic snouts at the luminal surface — is the diagnostic apocrine feature.
- Atypia, mitoses, lymphovascular invasion and necrosis distinguish carcinoma from benign apocrine adenoma.
- Immunohistochemistry: hormone-receptor positive (oestrogen, progesterone, androgen) in a significant proportion; GCDFP-15+, CK7+, EMA+, CEA+; HER2 amplification in subset.
- Mimics breast carcinoma metastasis — distinguishing primary skin from breast metastasis requires correlation with breast imaging and clinical history.
Management
- Wide local excision with 1–2 cm margins.
- Sentinel lymph node biopsy strongly recommended given high nodal metastatic risk.
- Imaging (CT or PET-CT) to exclude distant metastasis and rule out a breast/internal primary.
- Adjuvant radiotherapy for incomplete margins, multiple positive nodes or extracapsular extension.
- For metastatic / recurrent disease: hormone-receptor-directed therapy (tamoxifen, aromatase inhibitor, anti-androgen) for HR+ disease; HER2-targeted therapy (trastuzumab) for HER2+ disease (off-licence, supportive evidence).
- Chemotherapy options borrowed from breast carcinoma protocols.
Prognosis
Worse than other sweat-gland malignancies — regional metastasis ~40%, distant metastasis ~25%, 5-year overall survival 50–60%. Adverse prognostic factors include high tumour grade, lymphovascular invasion, positive nodes and large tumour size. Long-term surveillance is indicated, but there is no single universally accepted apocrine-carcinoma cadence; follow-up should be agreed by the specialist skin cancer / adnexal tumour MDT, with scar, nodal-basin and full-skin examination and imaging driven by stage, nodal status and symptoms.
References
- Robson A et al. Primary cutaneous apocrine carcinoma — clinicopathologic study. Am J Surg Pathol; 2008.
- Hollowell KL et al. Cutaneous apocrine carcinoma — review. Dermatol Surg; 2012.
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