A case of tall cell carcinoma with reversed polarity of the breast

Abstract

Tall cell carcinoma with reversed polarity (TCCRP) is a rare breast tumor recently defined in the fifth edition of the WHO Classification of Tumours of the Breast. Histologically, columnar neoplastic cells with reversed nuclear polarity display solid papillary nests. The IDH2 p.R172 hotspot mutation is frequently detected in TCCRP cases. Herein, we describe a case of TCCRP, emphasizing its cytological and histological features. A woman in her 40s presented with a mass in her left breast detected by mammography and ultrasonography. Fine-needle aspiration cytology revealed cuboidal to tall columnar neoplastic cells with nuclear grooves and intranuclear cytoplasmic inclusions, with reversed nuclear polarity in cohesive clusters. Core-needle biopsy demonstrated solid papillary nests with reversed nuclear polarity, leading to a diagnosis of TCCRP. Imprint cytology from the partial mastectomy specimen showed identical cytomorphology as that observed in the fine-needle aspiration cytology. Histology of the partial mastectomy specimen confirmed typical TCCRP morphology and revealed adipose tissue infiltration. Direct DNA sequencing of formalin-fixed, paraffin-embedded tumor tissue identified an IDH2:c.514A>G (p.Arg172Gly) mutation. Given the rarity of cytological descriptions of TCCRP, this case highlights the diagnostic value of cytomorphologic-histologic correlation.