We report a male patient with adult T-cell lymphoma, who was initially diagnosed clinically as having Henoch-Schönlein purpura (HSP) with abdominal pain and specific purpura. Adult T-cell lymphoma-like cells were minimal and abdominal lymph nodes were transiently swollen, and the symptoms were improved by supportive management. Although the clinical course was compatible with HSP, the histological examination revealed infiltration of lymphocytes rather than neutrophils. Later he developed lymphoma and was treated with chemotherapy. This rare case suggests the importance of skin biopsies to seek the underlying pathology in adult HSP.