HTLV-1-associated lymphocytic vasculitis presenting as acute appendicitis: A clinicopathological case report.

Human T-lymphotropic virus type 1 (HTLV-1) is associated with immune dysregulation, opportunistic infections, and, less commonly, lymphoproliferative and inflammatory disorders. We report the case of a young woman presenting with acute appendicitis, hyperkeratotic skin lesions, onychodystrophy, and subsequent facial diplegia. Investigation revealed HTLV-1 infection and crusted scabies, supporting an underlying immunosuppressed state. Histopathological examination of the appendix showed a transmural, angiocentric lymphocytic infiltrate involving small- and medium-sized vessels, without fibrinoid necrosis or leukocytoclasia. Immunohistochemical analysis demonstrated a predominance of CD4+ T lymphocytes with low proliferative index, consistent with a reactive process. These findings support a diagnosis of lymphocytic vasculitis presenting as acute appendicitis. Although a causal relationship cannot be definitively established, the clinicopathological and immunophenotypic features suggest a potential association with HTLV-1 infection, which has not been previously reported in this setting.