Final Diagnosis -- Infiltrating and Focal Intraductal Apocrine Carcinoma of Breast

FINAL DIAGNOSIS:

INFILTRATING AND FOCAL INTRADUCTAL APOCRINE CARCINOMA OF BREAST, METASTATIC TO IPSILATERAL AXILLARY AND SUPRACLAVICULAR LYMPH NODES

Discussion:

Apocrine cells reflect a metaplastic alteration of native epithelial cells and are a usual component of fibrocystic change. The apocrine phenotype is observed in a wide spectrum of breast epithelial lesions spanning benign metaplasias to carcinoma (1-3). The reported incidence of apocrine carcinoma varies considerably, ranging from less than 1% to 60%, reflecting varying diagnostic criteria which includes purely light microscopic features as well as reliance on antigenic markers (1). The latter specifically refers to immunohistochemical detection of GCDFP, as this protein is produced by metaplastic apocrine cells (4).

Apocrine carcinomas occur over a wide age range, although predominantly in the 6th and 7th decades. Grossly, these tumors are generally indistinguishable from invasive breast carcinomas, NOS and they present in a similar manner (1). Microscopically, apocrine carcinomas are composed of cords, sheets, and occasionally tubules of neoplastic cells (1,3). Cytologically, the tumor cells are large with relatively abundant, granular, eosinophilic cytoplasm and distinct cell margins; vesicular nuclei with prominent eosinophilic cytoplasm are characteristic (1,3). If an in-situ component is present, it is also usually of the apocrine type, as in the present case. Immunohisto-chemically, the majority of apocrine carcinomas express GCDFP-15 and androgen receptor, and lack immunohistochemically detectable ER and PR (1,3,5). The ultrastructural features of these carcinomas are variable but typically include the presence of mitochondria which are often numerous. Membrane-bound intracytoplasmic osmiophilic bodies are also described, and reportedly correspond to either the cytoplasmic eosinophilic granularity seen microscopically (6), or to the cellular GCDFP-15 content (7).

The prognosis of apocrine carcinoma is not clearly any different from invasive mammary carcinomas, NOS (3), although some reports suggest a somewhat better prognosis for this variant (1).

Tumors that enter the differential diagnosis of apocrine carcinoma include oncocytic carcinoma (8), squamous (metaplastic) carcinoma, histiocytoid carcinoma (9), lipid-rich carcinoma (10), granular cell tumor, and metastatic melanoma. Additionally, apocrine carcinomas arising in axillary apocrine glands should be distinguished from breast primaries.

References:

1. Tavassoli FA. Pathology of the breast. 2nd ed. Norwalk, CT: Appleton & Lange, 1999.
2. Tavassoli FA, Norris HJ. Intraductal apocrine carcinoma: a clinicopathologic study of 37 cases. Mod Pathol 1994;7:813-818.
3. Abati AD, Kimmel M, Rosen PP. Apocrine mammary carcinoma. A clinicopathologic study of 72 cases. Am J Clin Pathol 1990;94:371-377.
4. Wick MR, Lillemoe TJ, Copland GT, Swanson PE, Manivel JC, Kiang DT. Gross cystic disease fluid protein-15 as a marker for breast cancer: immunohistochemical analysis of 690 human neoplasms and comparison with alpha-lactalbumin. Hum Pathol 1989;20:281-287.
5. Tavassoli FA, Purcell CA, Bratthauer GL, et al. Androgen receptor positivity along with loss of bcl-2, ER, and PR expression in benign and malignant apocrine lesions of the breast. Implications for therapy. Breast J 1996;2:1-10.
6. Mossler JA, Barton TK, Brinkhous AD, McCarty KS, Moylan JA, McCarty KS Jr. Apocrine differentiation in human mammary carcinoma. Cancer 1980;46:2463-2471.
7. Eusebi V, Millis RR, Cattani MG, Bussolati G, Azzopardi JG. Apocrine carcinoma of the breast. A morphologic and immunocytochemical study. Am J Pathol 1986;123:532-541.
8. Damiani S, Eusebi V, Losi L, D'Adda T, Rosai J. Oncocytic carcinoma (malignant oncocytoma) of the breast. Am J Surg Pathol 1998;22:221-230.
9. Eusebi V, Foschini MP, Bussolati G, Rosen PP. Myoblastomatoid (histiocytoid) carcinoma of the breast. A type of apocrine carcinoma. Am J Surg Pathol 1995;19:553-562.
10. Wrba F, Ellinger A, Reiner G, Spona J, Holzner JH. Ultrastructural and immunohistochemical characteristics of lipid-rich carcinoma of the breast. Virchows Arch A Pathol Anat Histopathol 1988;413:381-385.

Contributed by Anna Mnuskin, MD, Susan A.Silver, MD and Anisa I. Kanbour, MB, ChB