Invasive Lobular Breast Carcinoma Can Be a Challenging Diagnosis Without the Use of Tumor Markers

Invasive lobular carcinoma is often challenging to diagnose due to the lack of physical examination findings and macrocalcifications on mammography. The cells of invasive lobular carcinoma form a distinct single file pattern that can be identified on histology slides. Often, when patients present, there is metastasis to the bones, lymph nodes, and gastrointestinal tract. Tumor markers are a valuable tool in identification, especially the loss of E-cadherin protein. However, if E-cadherin protein is not available, epidermal membrane antigen, which inhibits E-cadherin, can prove to be a significant diagnostic tool. Epidermal membrane antigen was the key tumor marker in our patient case. Other tumor markers and histology stains can drive treatment plans and help predict prognosis.