Diagnostic dilemma in a case of invasive mixed ductal lobular carcinoma of breast, a rare morphological subtype

Invasive mixed ductal lobular carcinoma (mDLC) is a rare subtype (3-5%) of invasive breast carcinoma. It is composed of mixed population of both invasive breast carcinoma of no special type (IBC-NST) and invasive lobular carcinoma (ILC) components within an individual tumor. We are presenting a case report of a 56yrs female who presented with lump left breast. On initial core needle biopsy reported as a case of lobular carcinoma breast. The Modified radical mastectomy (MRM) specimen showed both the components of invasive ductal and lobular carcinoma. So it was reported as Invasive Mixed breast carcinoma of no special type (NST)(60%) and Invasive Lobular carcinoma (40%). We are presenting this case of invasive mixed ductal-lobular carcinoma as there was dilemma in the diagnosis due to limited sampling by core needle biopsy and limited data is available on this tumor subtype. Here, we are presenting this case highlighting and enumerating its clinical presentation, radiological, histopathology and immunohistochemical features.