R-CHOP immunochemotherapy associated with symptom resolution and complete metabolic response in a case of intravascular large B-cell lymphoma.

ObjectiveTo highlight the diagnostic value of the ferritin-LDH-IL-10 triad and image-guided targeted biopsy in intravascular large B-cell lymphoma (IVLBCL) presenting as fever of unknown origin (FUO), with a review of relevant literature.MethodsWe present a case of a 60-year-old woman with a 10-month history of cough, progressive fever, and weight loss. We retrospectively analyzed her clinical course, laboratory profile, imaging findings, and histopathological results, and reviewed the relevant literature on IVLBCL diagnosis.ResultsExtensive initial investigations including multiple biopsies (bone marrow, colon, skin) and imaging were nondiagnostic. Persistent extreme hyperferritinemia (peak >15,000 ng/mL), markedly elevated LDH (735 U/L), and strikingly high IL-10 (>600 pg./mL) formed a diagnostic triad raising suspicion for IVLBCL. Re-review of PET-CT identified a subtle pulmonary FDG-avid focus (SUVmax 3.0), guiding video-assisted thoracoscopic wedge resection. Histopathology confirmed IVLBCL with CD20 + tumor cells within vascular lumina. The patient subsequently met criteria for secondary hemophagocytic lymphohistiocytosis. R-CHOP immunochemotherapy achieved rapid symptom resolution and complete metabolic response on follow-up PET-CT.ConclusionThe triad of extreme hyperferritinemia, elevated LDH, and markedly increased IL-10 may serve as a useful diagnostic clue to raise suspicion for IVLBCL in FUO patients, though its interpretation is confounded by secondary HLH and requires prospective validation. When random biopsies fail, multidisciplinary re-evaluation of PET-CT to identify subtle targets for image-guided biopsy is essential for definitive diagnosis. Early recognition of this triad and adoption of a hypothesis-driven biopsy strategy can significantly improve diagnostic outcomes in this elusive lymphoma.