Tall Cell Carcinoma of the Breast With Reverse Polarity: Expanding the Molecular Spectrum With IDH1 R132 Mutation

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Tall cell carcinoma with reversed polarity (TCCRP) is a rare invasive breast cancer.
• It shares histopathological similarities with papillary thyroid carcinoma.
• TCCRP possesses a distinct immunohistochemical and molecular profile.

Purpose of the Study:

• To present a case of TCCRP in a 72-year-old female.
• To detail the clinical, histopathological, immunophenotypic, and molecular characteristics of TCCRP.
• To discuss the treatment and prognosis of this rare breast cancer variant.

Main Methods:

• Case presentation of a 72-year-old female with a breast mass.
• Diagnostic workup including mammography, CT, and core biopsy.
• Surgical management with mastectomy and sentinel lymph node biopsy.
• Histopathological, immunohistochemical (IHC), and molecular analyses.
• Adjuvant radiotherapy and hormonal therapy (letrozole).

Main Results:

• Histopathology confirmed TCCRP.
• IHC and molecular analysis revealed hormone receptor-positive TCCRP with an IDH1 R132 mutation and low proliferative index.
• The patient remained disease-free at 18-month follow-up after multimodal treatment.

Conclusions:

• This case underscores the key features of TCCRP, including the rare IDH1 R132H mutation.
• Timely surgical and hormonal therapy leads to an excellent prognosis.
• Future research into targeted IDH1/IDH2 and PIK3CA therapies may offer expanded treatment options.