MEITL : Immunophenotype - CD8

Comments:
Immunophenotype: The neoplastic lymphocytes of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) are CD3+, CD5-, CD8+ (shown here), and CD56+. Most cases express T-cell receptor (TCR) gamma. A smaller number cases are TCR beta, TCR-silent, or express both TCR gamma and beta.

TIA1 is usually positive; however, other cytotoxic molecules, including granzyme B and perforin are variably expressed. About 20% of cases show aberrant expression of CD20.

Megakaryocyte-associated tyrosine kinase (MATK) is expressed by most cases of MEITL. This is helpful in its distinction from enteropathy-associated T-cell lymphoma which is MATK negative.