Metaplastic breast carcinoma with chondroid differentiation in a patient with prior ovarian carcinoma: A diagnostic dilemma

Abstract

Metaplastic breast carcinoma is a rare and aggressive subtype of invasive breast carcinoma accounting for <1% of allbreast malignancies. Among its variants, chondroid differentiation is particularly uncommon. A 36-year-old femalewith a known history of ovarian carcinoma, post total abdominal hysterectomy with bilateral salpingo-oophorectomy,and multiple cycles of chemotherapy including bevacizumab, presented with a gradually increasing lump in theright breast upper outer quadrant of 2 months’ duration. Fine-needle aspiration cytology confirmed malignancy.Sonomammography demonstrated a hypoechoic lesion (BIRADS IVA). Serial fluorodeoxyglucose-positron emissiontomography (PET/CT) scans documented complete metabolic resolution of previously noted outer quadrant lesions,followed by anew low-grade metabolically active lesion, raising the possibility of a metachronous primary. As PET-CTalone cannot reliably distinguish metastatic disease from a metachronous primary malignancy, definitive diagnosiswas established through histopathological examination and clinicopathological correlation. Wide local excision withright axillary clearance was performed. Histopathology revealed invasive carcinoma with a distinctive chondromyxoidstromal component and transition zones, consistent with metaplastic carcinoma with chondroid differentiation. All 15axillary lymph nodes were free of tumor. This case highlights the diagnostic complexity of a rare breast tumor subtypein the setting of a prior gynecological malignancy.