Meeting report on the possible proposal of an extranodal primary cutaneous variant in the lymphoma type of adult T-cell leukemia-lymphoma.

Based on the advances in research on the clinicopathophysiology of adult T-cell leukemia-lymphoma (ATL), Japanese researchers collected and evaluated cases of smoldering ATL exhibiting primary cutaneous manifestation but showing poor prognosis. Macroscopic findings of skin eruptions were categorized into the patch, plaque, multipapular, nodulotumoral, erythrodermic and purpuric types, as previously reported. Pathological findings were divided into low or high grade based on epidermotropism, tumor cell size and perivascular infiltration. Eight eligible cases were evaluated among 14 collected cases. Macroscopic findings were nodulotumoral in six cases, a subcutaneous tumor in one case and plaque in one case, and the number and size were heterogeneous in each case. Pathological findings of all eight cases were T-cell lymphoma, high-grade type (pleomorphic, medium or large size), with prominent perivascular infiltration and scant epidermotropism. To diagnose such cases as the "lymphoma type of ATL, extranodal primary cutaneous variant", it is essential to examine each case carefully, including cutaneous lesions at onset, lymph nodes and other organ involvement using computed tomography (CT) and/or positron emission tomography/CT, as well as the percentage of abnormal lymphocytes in peripheral blood. Based on the results of an ongoing nationwide survey on ATL, ATL with cutaneous lesions will be analyzed to investigate the incidence and prognosis of the so-called "lymphoma type of ATL, extranodal primary cutaneous variant".