When Vasculitis Is Not Vasculitis: A Case Report in Which Dynamic Immunophenotyping Revealed Hidden...

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.

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.

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.