Occult recurrence of monomorphic epitheliotropic intestinal T-cell lymphoma and the role of MATK gene expression in diagnosis.

Monomorphic epitheliotropic intestinal T-cell lymphomas (MEITL), formerly Type II enteropathy-associated T-cell lymphomas (EATL), are rare peripheral T-cell lymphomas. They are associated with poor survival outcomes, in part because of their late diagnosis. Although MEITLs may be reliably diagnosed based on histological and immunophenotypic findings, overlaps with other NK/T and T-cell lymphomas may confound the diagnosis. The distinctive high-level nuclear staining of the novel marker Megakaryocyte-associated tyrosine kinase (MATK) in MEITLs is an invaluable tool in distinguishing MEITL from classical EATL and other NK/T or T-cell lymphomas. 18-Fluorine-2-fluorodeoxyglucose positron emission tomography (18 F-FDG PET) has been shown to be a useful tool in the staging and follow-up of aggressive lymphomas. Herein, we describe an unusual case of occult hepatic recurrence of MEITL that was non-avid on 18 F-FDG PET, in which diagnosis was confirmed based on the expression of MATK in tumour cells.