Tall cell carcinoma with reversed polarity: case report with gene sequencing and literature review

Tall Cell Carcinoma with Reversed Polarity: Case Report of a Rare Special Type of Breast Cancer and Review of the Literature

Background: Tall cell carcinoma of the breast with reversed polarity (TCCRP) is a rare type of invasive breast cancer with overlapping features with papillary thyroid carcinoma and a characteristic molecular profile. Few cases have been reported in the literature since the first case was described in 2003. Case presentation: We present the case of a 41-year-old female with a symptomatic left breast lump. Image-guided core biopsy was diagnosed as triple-negative apocrine carcinoma. Surgical excision revealed an invasive carcinoma with solid papillary pattern, nuclei arranged away from the basement membrane (reversed polarity) and luminal eosinophilic colloid-like material. The tumour was GATA3-, CK5-, CK14- and CK7-positive and TTF1-negative. Specialist opinion and the identification of hotspot mutations in the IDH2 p.Arg172 gene via PCR confirmed the diagnosis of TCCRP. Conclusions: TCCRP is a relatively recently recognised papillary epithelial neoplasm with characteristic morphological features and molecular profile. Due to its rarity, TCCRP can be diagnostically challenging, and features can be mistaken for benign and malignant lesions. Accurate diagnosis is important in effective treatment of this indolent malignant triple-negative breast cancer, which carries an excellent prognosis.

Tall cell carcinoma with reversed polarity of breast: Sonographic and magnetic resonance imaging findings

Tall cell carcinoma with reversed polarity (TCCRP) of breast is a rare subtype of breast cancer, which show tall and columnar cells with nuclei of reversed polarity, resembles tall cell variant in papillary thyroid cancer. Only 78 cases in 20 published studies had been reported by 2021. TCCRP was recently included as a separate subgroup of rare tumors in the World Health Organization Blue Book Classification of breast tumors (5th edition). We describe a TCCRP case in a 64-year-old woman with detailed radiologic features including quantitative ultrasonography.

The Diagnostic Utility of IDH2 R172 Immunohistochemistry in Tall Cell Carcinoma With Reversed Polarity of the Breast

Tall cell carcinoma with reversed polarity (TCCRP) is a rare histologic type of low-grade breast cancer, consisting of tall columnar cells with reversed nuclear polarity and characterized by frequent IDH2 mutations. We herein report 3 cases of TCCRP with sequencing analyses of the IDH2 gene and immunohistochemical examination using monoclonal antibodies (11C8B1) against IDH2 R172. IDH2 R172 mutations were detected in all 3 resected tumors (R172S in 2 tumors and R172T in 1 tumor), and the presence of these mutations was confirmed by IDH2 R172 immunohistochemistry. Tumor cells of TCCRP showed strong and diffuse staining for the antibody against IDH2 R172. In 1 case, tumor tissue from 2 core needle biopsy samples collected on different days were also immunohistochemically positive for IDH2 R172. These results indicate that IDH2 R172 immunohistochemistry is suitable for the detection of TCCRP in both resection and biopsy samples. In addition, a literature review revealed that R172S and R172T account for 76% of IDH2 mutations in TCCRP, suggesting that 11C8B1, which reacts with R172S and R172T, was likely most sensitive for IDH2-mutated TCCRP among many available antibodies for IDH2 R172. Furthermore, the combination of 2 or more antibodies against IDH2 R172 could be more effective for detecting TCCRP mutation. However, it is important to note that IDH2 R172 immunohistochemistry is not absolute, because IDH2 wild type is found in a small proportion (10%) of cases, and a few cases of IDH2-mutated TCCRP may harbor rare subtypes of R172 that are not covered by available antibodies.