Tall Cell Carcinoma with Reversed Polarity in the Breast: A Case Report with Review of Literature

Abstract Tall cell carcinoma with reversed polarity (TCCRP) is a relatively new entity that is recognized as a subtype of epithelial tumors of the breast in the latest World Health Organization classification of breast tumors (fifth edition). This tumor bears close morphological resemblance to the tall cell subtype of papillary carcinoma of the thyroid. TCCRP is recognized by its distinct morphologic and immunohistochemical patterns, occasionally aided by molecular analysis for the presence of associated characteristic IDH2 mutations. A 42-year-old woman with a left breast lump was evaluated at another institute and diagnosed with invasive mammary carcinoma (no special type), and subsequently underwent a modified radical mastectomy. Our institute received the case for review. On histopathological examination, the sections revealed a fairly circumscribed lesion composed of nests of tall cells with apically located nuclei. After correlation with immunohistochemistry markers, a diagnosis of TCCRP was established. The patient was further managed with adjuvant chemotherapy and was declared disease-free on 1-year follow-up. We report this lesion as it is a novel breast tumor, and a thorough understanding of its morphological appearance is essential to establish the diagnosis. A lack of awareness may result in misdiagnosis, with the lesion possibly being categorized as a nonspecific malignancy or misinterpreted as another papillary breast lesion. Given its favorable prognosis, accurate diagnosis of this tumor is imperative. When evaluating papillary breast lesions, TCCRP should be a key differential consideration.