# A case of marginal zone lymphoma presenting with paraneoplastic vasculitis and pulmonary infiltration

## TL;DR

A 73-year-old man with marginal zone lymphoma showed rare paraneoplastic vasculitis and lung issues, which improved with rituximab treatment.

## Contribution

This case highlights the rare presentation of marginal zone lymphoma with paraneoplastic vasculitis and pulmonary infiltration.

## Key findings

- The patient had CD20-positive extranodal marginal zone lymphoma confirmed by PET-CT and biopsies.
- Rituximab monotherapy led to clinical and radiological improvement in both lymphoma and vasculitis.
- Paraneoplastic vasculitis occurred without classical autoimmune markers, emphasizing the need for malignancy screening.

## Abstract

Paraneoplastic vasculitis is a rare but important manifestation of underlying malignancies, most commonly hematological, and often presents with atypical features resistant to standard immunosuppression. Marginal zone lymphoma (MZL), a low-grade B-cell lymphoma, may infrequently present with pulmonary involvement and paraneoplastic immune phenomena.

We report a 73-year-old male with a history of COPD who presented with progressive dyspnoea, weight loss, lower limb purpura, and pancytopenia. Initial suspicion included pneumonia and COPD exacerbation; however, imaging revealed bilateral pulmonary infiltrates and pleural effusion. Laboratory evaluation showed systemic inflammation and worsening cytopenias. Further workup, including PET-CT and biopsies, identified CD20-positive extranodal marginal zone lymphoma with pulmonary infiltration. The patient developed presumed paraneoplastic vasculitis involving the skin and coronary arteries, in the absence of classical autoimmune markers. Rituximab monotherapy was initiated, resulting in both clinical and radiological improvement.

This case highlights the importance of considering underlying malignancy in patients with unexplained systemic inflammation, vasculitic skin lesions, or cytopenias, particularly when autoimmune markers are negative. Prompt histological diagnosis and multidisciplinary collaboration enabled timely immunochemotherapy, resulting in the resolution of both lymphoma and associated paraneoplastic complications.