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20. A CASE REPORT OF ADENOID CYSTIC CARCINOMA (ACC) OF THE BREAST

Case summary: A 60-year-old woman with a painful breast lump was diagnosed with adenoid cystic carcinoma (ACC). The tumour had solid cribriform and tubular growth patterns with true and pseudo-lumens. The epithelial component was positive for cytokeratin 5/6 and the myoepithelial component was positive for calponin. The oestrogen and progesterone stains were negative, and the Ki-67 was approximately 3–5%. Discussion: ACC of the breast is a rare neoplasm accounting for 0.1% of all breast cancers.1 It is of special interest because of its more favourable prognosis compared to ACC of the salivary glands and other types of breast cancers. It also presents difficulties with the differential diagnoses. The growth patterns seen in ACC may resemble collagenous sperulosis, cribriform carcinoma, small cell carcinoma, solid papillary carcinoma and even lymphoma. Immunohistochemistry to identify the dual epithelial-myoepithelial cell populations, and the typically negative estrogen and progesterone receptors help lead to the correct diagnosis of ACC.2 Conclusion: ACC of the breast is rare but has an excellent prognosis when it is accurately diagnosed. ReferencesTavassoli F, Devilee P. WHO Tumours of the Breast and Female Genital Organs. Lyon: IARC Press, 2003; 44–5.Schnitt SJ, Collins L. Biopsy Interpretation of the Breast. Philadelphia: Lippincott Williams and Wilkins, 2008; 285–9.