Syringocystadenocarcinoma papilliferum (SCACP) is a rare form of adenocarcinoma of the skin. This is the malignant counterpart of syringocystadenoma papilliferum (SCAP) and usually develops on the scalp in a long-standing lesion identified clinically as SCAP. We describe a 65-yr-old Korean man with a nodule on the right supra-pubic area with a 2-yr duration. Histologically this tumor had a similar overall configuration as in SCAP, but the tumor was asymmetric and poorly circumscribed, extending into the deep dermis and showed cytologic atypia. The tumor cells showed positive reaction to GCDFP-15, but negative reaction to CEA and HMFG-1. We established the diagnosis of SCACP in the patient, and a wide excision was performed to remove the tumor. The patient has been well without relapse or metastasis for 2 yr.
Aged ; Carrier Proteins/analysis ; Cystadenocarcinoma, Papillary/metabolism/*pathology ; Glycoproteins/analysis ; Humans ; Immunohistochemistry ; Male ; Sweat Gland Neoplasms/metabolism/*pathology ; Syringoma/metabolism/*pathology

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Adolescent ; Adult ; Female ; Humans ; Male ; Middle Aged ; Receptors, Estrogen/analysis ; Receptors, Progesterone/analysis ; Sweat Gland Neoplasms/*metabolism/pathology/therapy ; Syringoma/*metabolism/pathology/therapy

OBJECTIVETo investigate the pathologic and immunohistochemical features, diagnosis and differential diagnosis of low-grade adenosquamous carcinoma of the breast and syringomatous adenoma of the nipple.

METHODSSix cases of low-grade adenosquamous carcinoma of the breast and four cases of syringomatous adenoma of the nipple were examined histologically and immunohistochemically (MaxVision method), and the literature was reviewed.

RESULTSThe two types of tumors were similar in morphology, but located in different regions with low-grade adenosquamous carcinoma being present in the deep parenchyma and syringomatous adenoma in nipple. Both types of tumors were composed mainly of well-differentiated glands with angulated, comma shaped or polliwog appearance in a disordered infiltrative pattern. The tumor cells also formed solid tubules, strips or nests, with frequent areas of squamoid differentiation. Mitosis was rare. The interstitial tissue showed abundant spindle cells or sclerotic fibrosis with mixed inflammatory cells infiltration. One case of low-grade adenosquamous carcinoma showed a concomitant malignant adenomyoepithelioma, and another case showed concomitant spindle cell metaplastic carcinoma. One case of syringomatous adenoma involved the deep parenchyma. Immunohistochemistry of low-grade adenosquamous carcinoma showed that CK5/6 and p63 were positive in the outer layer of the glands and the squamoid epithelium, and CD10 was also positive in the outer layer of the glands. ER and HER2 were negative, and PR was also negative except for one case in which the spindle cells were positive for CK5/6, AE1/AE3 and PR focally. Immunostaining of syringomatous adenoma demonstrated that p63 and CK5/6 were positive in the outer layer of the glands and the squamoid epithelium. Calponin, SMA, ER, PR and HER2 were all negative.

CONCLUSIONSLow-grade adenosquamous carcinoma of the breast and syringomatous adenoma of the nipple are similar in morphology and immunohistochemical phenotype, while the biological features are opposite due to different locations. The differential diagnoses include tubular carcinoma, adenosquamous carcinoma, radial sclerosing lesions and others.

Adenocarcinoma ; pathology ; Adult ; Aged ; Breast ; pathology ; Breast Neoplasms ; diagnosis ; metabolism ; pathology ; Carcinoma, Adenosquamous ; diagnosis ; metabolism ; pathology ; Carcinoma, Squamous Cell ; pathology ; Diagnosis, Differential ; Female ; Humans ; Immunohistochemistry ; Keratin-5 ; metabolism ; Keratin-6 ; metabolism ; Middle Aged ; Neprilysin ; metabolism ; Nipples ; pathology ; Sclerosis ; Sweat Gland Neoplasms ; diagnosis ; metabolism ; pathology ; Syringoma ; diagnosis ; metabolism ; pathology ; Transcription Factors ; metabolism ; Tumor Suppressor Proteins ; metabolism