Clinical features

•Very rare

•M=F

•Age range 18-91

•Axilla>>scalp, eyelid, ear, anogenital region, chest, lip & wrist

•Slowly growing sometimes ulcerated nodule or plaque

•Rarely develops in a nevus sebaceus or complicates a benign precursor apocrine tumor

•Often slowly growing and fairly indolent although high grade variants are not uncommon

•Metastases to lymph nodes (50%), lung and bone

•Recurrence rate 28%

•Median survival: 51.5 months

•Nodal and distant metastasis are poor prognosis indicators

•Before accepting a tumor as being a cutaneous primary, the presence of an apocrine carcinoma elsewhere (particularly the breast) must always be excluded

Histological features

•May develop in a background of a benign precursor tumor or exceptionally nevus sebaceus

•Poorly circumscribed tumor nodule with invasive border

•Rarely cystic

•Variable glandular, tubular, papillary, tubulo-papillary, diffuse and solid growth patterns

•Can be associated with overlying Paget’s disease

•Large cells with vesicular nuclei and often prominent nucleoli

•Decapitation secretion

•Variable pleomorphism, mitotic activity & atypical mitoses

•Variable necrosis

•Variable lymphovascular involvement & perineural infiltration

•Exceptionally squamous, clear cell, granular cell and sebaceous differentiation

•Exceptionally single file and signet ring growth pattern (see signet ring cell carcinoma)

•Intracytoplasmic DPAS +ve granules

•? Grade as per the modified Blook Richardson classification (I-3)

Immunohistochemistry (all images are courtesy of Dr. Kalmykova except for CK7 which was shared by Dr. Phyo)

•CAM 5.2, AE1/AE3, CK5/6, EMA, CEA, GATA3, androgen receptor, GCDFP15 and D2-40 positive

•Variable S100, SMA and p63 expression

•Variable estrogen and progesterone expression

•Adipophilin & HER2/neu negative

Differential diagnosis

Cutaneous apocrine carcinoma must always be distinguished from a breast primary tumor. Some immunohistochemical guidelines are shown in the table below.

David Paton

Thank you for this helpful link! I think it’s important to say that while most breast carcinomas are ER+/PR+/AR- (hence this IHC panel is generally helpful in the distinction) breast apocrine carcinoma is characteristically triple negative (ER-/PR-/HER2-) and AR+.