IHC EMA with interpretation Test

Epithelial membrane antigen (EMA) is a large cell surface mucin glycoprotein that is expressed by some hematopoietic cells and most of the ductal and glandular epithelial cells. It plays a regulatory and protective role by acting as a barrier to the apical surface of epithelial cells. It is highly expressed by many adenocarcinomas. It is shed into the adenocarcinoma patients’ bloodstream and is used in serum tumour marker assays. EMA is one of the immunohistochemical markers, which help in distinguishing malignant from benign mesothelial proliferation in a cytologic specimen.

Specimen preparation: either tissue or cells are collected. the Specimen is then formalin-fixed and paraffin embedded. If cells are used, they must be prepared into a cellblock. The block or slides are protected from exposure to excess heat. They are either kept at room temperature or refrigerated but are never frozen.

It is a common epithelial marker. It acts as a marker of meningioma and Paget’s disease. IHC-EMA test is also used for detecting breast and bladder micropapillary carcinoma and differentiating cutaneous anaplastic large cell lymphoma from systemic anaplastic large cell lymphoma.

There are four steps in IHC-EMA: fixation (to retain tissue architecture and cell morphology), antigen retrieval (to heighten the availability of protein for detection), blocking (to lessen the unnecessary background signals) and antibody labelling (to view and interpret the results). Interpretation: positive staining (normal)—for almost all glandular and ductal epithelial cells. Positive staining (disease)—for adenocarcinomas, carcinoid tumour, epithelioid sarcoma, meningioma, myeloma, Paget’s disease, renal cell carcinoma, etc. Negative staining—for germ cell tumours, liposarcoma, neuroblastoma, melanoma, adrenal and hepatocellular carcinoma, etc.