Track: Case Reports

Abstract:

Intravascular large B-cell lymphoma (IVLBCL) is a rare, aggressive subtype of extranodal diffuse large B-cell lymphoma. Pathologically, it is defined by neoplastic B-lymphocytes proliferating within small-to-medium-sized-blood vessels, causing microvascular occlusion and subsequent organ-dysfunction. IVLBCL is categorized into three distinct clinical variants: classic, hemophagocytic-syndrome-associated, and a cutaneous form. IVLBCL is a pertinent differential diagnosis among intravascular reactive and neoplastic processes.

We present a case of an 86-year-old male who presented with a five-week history of rapidly progressing, violaceous, non-blanchable patches and thin plaques on his bilateral inner thighs, accompanied by mild pruritus. His past medical history was significant for prostate cancer status post-radiation therapy. A punch-biopsy was performed with a clinical differential diagnosis including angiosarcoma, Kaposi sarcoma, and B-cell-lymphoma. Histologically, the biopsy revealed numerous enlarged lymphocytes within small vessels throughout the dermis and subcutis. The atypical lymphocytes stained positive for CD20, BCL-2, BCL-6, MUM-, and CD5, confirming diagnosis of IVLBCL.

The patient was referred to oncology to rule out systemic disease. A PET scan was performed, which revealed localized FDG-avid subcutaneous thickening without generalized lymphadenopathy or distant metastasis. The patient was treated with R-CHOP and intrathecal methotrexate. Follow-up imaging showed no new lesions, and multiple cerebrospinal fluid analyses were negative for a B-cell lymphoproliferative process, ruling out central-nervous-system involvement.

This case highlights the need for a broad differential diagnosis of intravascular processes. Beyond well-known vascular neoplasms like angiosarcoma and Kaposi sarcoma, and reactive conditions like intravascular histiocytosis and intravascular papillary endothelial hyperplasia, the differential must also include rare entities such as IVLBCL.

Kevin Paul

Affiliation

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(199) Intravascular Large B-Cell Lymphoma: A Rare Mimic of Reactive and Neoplastic Intravascular Processes