Tall cell carcinoma of the breast with reversed polarity (TCCRP) with mutations in the IDH2 and PIK3CA genes: a case report.

Tall cell carcinoma with reversed polarity (TCCRP) is a rare breast carcinoma with low malignant potential, initially named "breast tumor resembling the tall cell variant of papillary thyroid carcinoma", which has recently been recognized as a separate entity in the 5th edition of the WHO (World Health Organization) classification of breast tumors. Since the first report of this entity in 2003, more than 40 cases have been reported in the literature. Here, we report another case of this rare tumor in a 60-year-old woman. We performed immunohistochemical analyses and next-generation-sequencing (NGS) using the Oncomine™ Comprehensive DNA Panel (Thermo Fisher Scientific). The tumor showed the typical morphological features of TCCRP and a "triple-negative" phenotype. Moreover, we identified pathogenic mutations in the IDH2 (p.R172G) and PIK3CA (p.H1047R) genes. We report a case of TCCRP of the breast showing the characteristic morphologic, immunohistochemical and molecular features of this entity. There is still a limited number of cases with comprehensive molecular analyses reported in the literature. Therefore, we herewith contribute to a better understanding of the morphological and molecular characteristics as well as the clinical behavior of this rare entity.

Clinicopathological characterization of tall cell carcinoma with reversed polarity of the breast: A case report and review of the litterature.

INTRODUCTION: Tall cell carcinoma of the breast with reverse polarity (TCCRP) is a recently described rare entity with low potential for malignancy which exhibits morphological features with tall cell variant of papillary thyroid carcinoma. Immunohistochemical and molecular studies help establish the diagnosis. CASE REPORT: We report the case of a 45-year-old woman with no significant medical or surgical history who presented with mastodynia. Physical examination was negative. Screening by bilateral mammography revealed a mass of the right breast which was classified as 4B. The mass was surgically excised. The pathological report concluded to a TCCRP of the breast with free margins. The tumor cells were negative for hormone receptors as well as for the Human Epidermal Growth Factor Receptor-2 (HER2neu). The patient underwent a sentinel lymph node dissection that was negative followed by loco-regional radiotherapy. Chemotherapy and endocrine therapy were not indicated for the patient. After 24 months of follow-up, no signs of loco-regional or distant recurrences have been identified. CLINICAL DISCUSSION: TCCRP is a rare entity that has been recently introduced in the WHO classification of breast cancer. It is usually a triple negative tumor, negative to TTF1 and thyroglobulin with low proliferation index, and a low potential for malignancy. Wide excision is the keystone of the treatment; however, chemotherapy and radiotherapy are still controversial due to lack of evidence. CONCLUSION: TCCRP is a rare entity, which carries an excellent prognosis. A proper diagnosis is essential to conduct the best treatment next to a careful follow-up due to the ambiguous natural history of this rare entity. PAPERS THAT HAVE BEEN PREVIOUSLY PUBLISHED AS MEETING ABSTRACTS: None.

Imprint Cytology of Tall Cell Carcinoma with Reversed Polarity of the Breast: A Case Report.

INTRODUCTION: Tall cell carcinoma with reversed polarity (TCCRP) is a rare histologic subtype of breast cancer that was newly categorized in 2020. TCCRP is a relatively novel tumor, and there are no detailed reports about its cellular morphology. We were able to obtain imprint cytological specimens from fresh TCCRP tissue, and we provide our detailed observations. CASE PRESENTATION: The patient was a 73-year-old Japanese female with a 15-mm mass in her right breast. After invasive breast carcinoma was diagnosed based on a core needle biopsy, a lumpectomy was performed. The pathological examination revealed TCCRP, and Sanger sequencing detected IDH2 p.R172M hotspot mutation, which is characteristic of TCCRP. Soon after the surgery, the lumpectomy specimen was sliced before fixation for use in a clinical trial, and imprint cytological materials were obtained from the tumor's cut surface. Cytologically, the tumor showed papillary-like cell clusters and isolated cells with moderate cellularity. Neoplastic cell aggregates and clusters with thick vascular cores as the axis or with delicate fibrovascular stroma were observed. Most of the neoplastic cells were cuboidal-to-columnar in shape, with mildly to moderately irregularly shaped blunt nuclei. Some intranuclear cytoplasmic inclusions and nuclear grooves were present, resembling the nuclear findings of papillary thyroid carcinoma. The most characteristic finding was the columnar cell clusters with apically located nuclei, giving the impression of reversed polarity. CONCLUSION: We described cytological findings in TCCRP, a newly classified rare mammary tumor. Most of the characteristic histologic findings were also observed in imprint cytological specimens. Further studies on practical specimens such as fine-needle aspiration are needed for clinical application.

Case report: Tall cell carcinoma with reversed polarity of the breast: an additional case and review of the literature.

Objective: The aim of this report was to comprehensively investigate the clinicopathological features, histological characteristics, and differential diagnosis of tall cell carcinoma with reversed polarity of the breast (TCCRP) to enhance the understanding of this tumour for precise therapeutic interventions. Methods: The clinicopathological characteristics and differential diagnosis of a patient with TCCRP were retrospectively analysed, and a systematic literature review was extracted from relevant published studies on PubMed. Results: All patients included in the study were female, with a median age of 51 years. Microscopically, the tumour cells exhibited a solid papillary growth pattern with tall columnar morphology and reversed nuclear polarity. Immunohistochemistry revealed that the tumours were triple-negative breast cancer (negative for ER, PR, and HER-2), with a low Ki-67 proliferation index. Different degrees of expression were observed for CK7, Calretinin, and S-100 markers; however, CK5/6 showed high expression levels. Conclusions: TCCRP is an uncommon invasive carcinoma subtype found in the breast. Its histological morphology resembles that of tall cell subtype papillary thyroid carcinoma. Accurate diagnosis requires the integration of histomorphological assessment along with immunohistochemistry and molecular genetics analysis.

Breast carcinomas of low malignant potential.

Some breast carcinomas have a very low likelihood of metastasis to regional lymph nodes and distant sites and may be considered carcinomas of low malignant potential. In this article, we review the clinical, pathologic, immunophenotypic, and molecular features of selected breast carcinomas of low malignant potential including low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, encapsulated papillary carcinoma, solid papillary carcinoma, and tall cell carcinoma with reversed polarity.

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

Tall cell carcinoma with reversed polarity (TCCRP) is an extremely rare type of invasive breast cancer with only 17 literatures and 75 cases reported. Knowledge on TCCRP is still scanty. The present study reported 2 cases of TCCRP, analyzed their clinicopathological characteristics, and used whole exome sequencing to perform genetic testing. Both two cases were proved to have typical clinicopathological manifestations (solid and papillary architectures lined by tall columnar cells with nuclei displaying "reverse polarization") and hotspot mutations (IDH2 and PIK3CA mutations) of TCCRP. Furthermore, positive expression of TTF-1 was found in a small number of tumor cells nuclei and normal ductal epithelial cells, while the negative rate of TTF-1 in previous case reports was 100%. Attention should be paid in core needle biopsy to avoid misdiagnosis. In addition, this article also reviewed all previous cases and demonstrated that the positive expression of calretinin might have an indicative significance for TCCRP, which could be used as one of the auxiliary diagnosis tools. The diagnosis of TCCRP requires comprehensive analysis of clinical pathology and genetic testing results. There is no clear treatment standard for TCCRP currently, further research should be reported to characterize and deeply investigate the diagnosis and treatment criteria of TCCRP.

Triple-Negative Breast Cancer Histological Subtypes with a Favourable Prognosis.

Triple-negative breast cancers (TNBC), as a group of tumours, have a worse prognosis than stage-matched non-TNBC and lack the benefits of routinely available targeted therapy. However, TNBC is a heterogeneous group of neoplasms, which includes some special type carcinomas with a relatively indolent course. This review on behalf of the European Working Group for Breast Screening Pathology reviews the literature on the special histological types of BC that are reported to have a triple negative phenotype and indolent behaviour. These include adenoid cystic carcinoma of classical type, low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, low-grade mucoepidermoid carcinoma, secretory carcinoma, acinic cell carcinoma, and tall cell carcinoma with reversed polarity. The pathological and known molecular features as well as clinical data including treatment and prognosis of these special TNBC subtypes are summarised and it is concluded that many patients with these rare TNBC pure subtypes are unlikely to benefit from systemic chemotherapy. A consensus statement of the working group relating to the multidisciplinary approach and treatment of these rare tumour types concludes the review.