Nasal type extranodal natural killer (NK)/T-cell lymphoma, previously referred to as lethal midline granuloma, is a lymphoma characterized by Epstein-Barr virus (EBV) positivity and NK cells or, less commonly, cytotoxic T cells. The nasopharynx is most commonly involved (80% of cases), followed by the skin. Lesions are composed of firm papules or nodules that rapidly expand, ulcerate, and destroy surrounding tissue. Skin disease may be primary or secondary. Multiple sites can be involved, including the gastrointestinal (GI) tract, testes, salivary gland, uterus, and muscle. Hemophagocytic syndrome with pancytopenia can further aggravate the clinical course.

The disease is exceedingly rare in the United States and Europe but more common in Central / South America and Asia. Adults are most frequently affected, but cases in children have been reported.

EBV exposure is a key risk factor, and detection of the virus in lymphoma cells is required for diagnosis. Genetic aberrations such as deletion of chromosome 6q and possible abnormalities in the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway have been implicated.

Treatment is difficult and includes chemotherapy and/or radiation therapy.

Related topic: Non-Hodgkin lymphoma