# Systemic B-cell lymphoma with preceding myelin oligodendrocyte glycoprotein antibody-associated disease: a case report and literature review

## TL;DR

A rare case is described where a patient with MOGAD was later found to have systemic B-cell lymphoma, suggesting MOGAD might be an early sign of the cancer.

## Contribution

This case report highlights the rare coexistence of MOGAD and B-cell lymphoma and suggests MOGAD could be a paraneoplastic manifestation of lymphoma.

## Key findings

- MOGAD was confirmed via cell-based assays with MOG-IgG positivity in serum and cerebrospinal fluid.
- The patient's pancytopenia and immunophenotyping led to the diagnosis of systemic B-cell lymphoma.
- The case suggests MOGAD may be a sentinel manifestation of an underlying lymphoma.

## Abstract

The co-occurrence of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and hematological malignancies is infrequently described. We report a rare case of histopathologically confirmed MOGAD complicated by pancytopenia following corticosteroid therapy, which ultimately unveiled a concurrent systemic B-cell lymphoma.

A 76-year-old female presented with bilateral lower limb weakness and numbness persisting for two months. She was initially diagnosed with acute myelitis at an external institution and treated with intravenous methylprednisolone (IVMP). A relapse occurred one month after corticosteroid cessation. Upon admission, magnetic resonance imaging (MRI) demonstrated an enlarging spinal cord lesion and extensive enhancement of the cauda equina nerve roots. A spinal cord biopsy revealed necrosis, chronic inflammatory infiltration, and demyelination, without definitive evidence of tumor cells or atypical lymphoid cells. Immunohistochemical staining revealed a loss of MOG expression, while neurofilament (NF) staining confirmed relative axonal integrity with only focal loss within the affected area. The diagnosis of MOGAD was confirmed via cell-based assays, which showed MOG-IgG positivity in both serum (1:32) and cerebrospinal fluid (1:1). However, the patient was refractory to further IVMP treatment and subsequently developed fever and pancytopenia. Peripheral blood immunophenotyping and bone marrow biopsy eventually established a diagnosis of systemic B-cell lymphoma.

The coexistence of MOGAD and systemic B-cell lymphoma is rare. This case suggests that MOGAD may serve as a sentinel paraneoplastic manifestation of an underlying lymphoma.