A CD30-positive variant of intravascular large B-cell lymphoma presenting as diffuse interstitial lung disease and generalized lymphadenopathy: a case report.

Introduction: Intravascular large B-cell lymphoma (IVLBCL) is a rare and aggressive malignancy defined by the proliferation of neoplastic B-cells within the vascular lumen. While the disease can affect multiple organs, commonly manifesting as skin lesions, neurological deficits, or hepatosplenomegaly, it usually spares the lymph nodes and rarely presents as diffuse interstitial lung disease (DILD). We report a 62-year-old man admitted with recurrent fever and progressive dyspnea. Chest computed tomography revealed extensive bilateral interstitial lung disease, with ultrasonography showing generalized lymphadenopathy with preserved architecture. Although initial therapy led to a favorable response, the patient subsequently relapsed. Lymph node biopsy confirmed IVLBCL, characterized by intravascular and intrasinusoidal lymphoma cell infiltration with well-preserved nodal architecture. Notably, the tumor cells showed diffuse strong CD30 expression (~70%), a rare finding potentially linked to the unusual clinical presentation. Conclusion: This case demonstrates that IVLBCL can present with diffuse interstitial lung disease and generalized lymphadenopathy, expanding its recognized phenotypic spectrum. It may represent a variant with CD30-mediated nodal homing and immune activation.