RT Journal Article SR Electronic T1 When Vasculitis Is Not Vasculitis: A Case Report in Which Dynamic Immunophenotyping Revealed Hidden Angioimmunoblastic T-cell Lymphoma JF In Vivo JO In Vivo FD International Institute of Anticancer Research SP 1842 OP 1851 DO 10.21873/invivo.14338 VO 40 IS 3 A1 LIN, I-YAO A1 LU, JENG-WEI A1 HO, YI-JUNG A1 LUI, SHAN-WEN A1 HSIEH, TING-YU A1 JHENG, WUN-LONG A1 LIU, FENG-CHENG YR 2026 UL http://iv.iiarjournals.org/content/40/3/1842.abstract AB Background/Aim: Angioimmunoblastic T-cell lymphoma (AITL) is a rare peripheral T-cell lymphoma characterized by diverse and aggressive clinical manifestations that frequently mimic autoimmune disorders. Cutaneous presentations are common and may lead to diagnostic delay.Case Report: A 67-year-old woman first presented with non-blanchable skin rash, with normal platelet count and negative autoimmune markers. The rash improved with corticosteroids but recurred two months later, accompanied by fever, night sweats, limb edema, diarrhea, and cervical lymphadenopathy. Skin biopsy reported vasculitis and panniculitis, as direct immunofluorescence was compatible with IgA vasculitis. Subsequent laboratory tests revealed atypical lymphocytes, Coombs-positive anemia, thrombocytopenia, and detected Epstein-Barr virus DNA. Computed tomography showed new splenomegaly and periaortic lymphadenopathy. Lymph node biopsy confirmed AITL. Although CHOP chemotherapy was planned after staging, the patient rapidly deteriorated and died of septic shock. Serial peripheral blood flow cytometry at admission, post-splenectomy, and follow-up showed dynamic immunophenotypic changes: reductions in exhaustion and senescence markers as well as activated regulatory T cells after splenectomy; and later upregulation of exhaustion markers on naïve T cells.Conclusion: This case illustrates the misleading presentation as immunoglobulin A (IgA) vasculitis and rapid progression of AITL. While vasculitis is accompanied by cytopenia, lymphadenopathy, or aggressive clinical course, early lymph node biopsy is essential for timely diagnosis.