E-CADHERIN–POSITIVE INVASIVE LOBULAR CARCINOMA: A CLINICOPATHOLOGICAL DIAGNOSTIC DILEMMA

Abstract

Breast carcinoma remains the most frequently diagnosed malignancy among women worldwide. Invasive lobular carcinoma (ILC) constitutes approximately 10–15% of all breast cancers and is classically associated with loss of E cadherin expression. We report a case of a 76-year-old female presenting with a gradually enlarging right breast lump with associated nipple retraction. Imaging suggested a suspicious lesion (BI-RADS IV). Histopathological examination following trucut biopsy confirmed malignancy. The patient underwent modified radical mastectomy with axillary clearance. Final histopathology revealed invasive lobular carcinoma with vascular invasion and metastasis to one lymph node. Immunohistochemistry demonstrated ER positivity (90%), PR negativity, HER2 equivocal (2+), Ki-67 index of 15%, and retained E-cadherin expression. This unusual immunophenotype posed a diagnostic challenge. This case highlights the importance of correlating histomorphology with immunohistochemical findings to ensure accurate tumor classification and appropriate management.