Diffuse Large B-Cell Lymphoma Presenting With Superior Vena Cava Syndrome and Recurrent Pleural Effusions in a Patient With Angelman Syndrome: A Case Report.

Superior vena cava (SVC) syndrome is an uncommon but important presentation of mediastinal malignancy and can rapidly progress to respiratory compromise. We report a case of diffuse large B-cell lymphoma (DLBCL) in a patient with Angelman syndrome and seizure disorder, highlighting the diagnostic and airway challenges encountered during evaluation. A 42-year-old woman with Angelman syndrome presented with progressive neck and facial swelling after two weeks of fever, chills, and rhinorrhea. She reported worsening dyspnea and was admitted for concern for superior vena cava syndrome. Chest imaging showed extensive mediastinal, hilar, and cervical lymphadenopathy with bilateral pleural effusions and atelectasis, raising concern for lymphoma or metastatic disease. Cardiothoracic surgery was consulted, but mediastinoscopy was deferred because of her short stature and the location and size of the mediastinal mass. The patient's caregiver initially refused thoracentesis. Her respiratory status worsened, requiring high-flow oxygen for hypoxemia. She was transferred to a tertiary center for further evaluation. At the tertiary center, pulmonology deferred endobronchial ultrasound because of concern that adequate lymph node tissue could not be obtained due to the patient's small airway, which could permit only a 6 mm endotracheal tube. The patient subsequently underwent cervical lymph node core needle biopsy and thoracentesis. Thoracentesis yielded approximately 800 mL of yellow-green pleural fluid that had 32% lymphocytes and was exudative based on lactate dehydrogenase (LDH). Pleural fluid flow cytometry was positive for malignancy, showing an abundant monotonous lymphoid population and kappa-restricted clonal B-cells. Thoracentesis on the contralateral side showed an exudative effusion with similar findings. Pleural fluid flow cytometric immunophenotyping showed kappa clonal B-cells expressing CD19 and CD20, and lacking CD10, CD200, and CD38, with equivocal expression of CD5. Cervical lymph node pathology confirmed diffuse large B-cell lymphoma. The patient was started on rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) with a good clinical response. Her course was complicated by prolonged mechanical ventilation due to respiratory muscle weakness requiring tracheostomy. This case illustrates an unusual presentation of diffuse large B-cell lymphoma with superior vena cava syndrome and bilateral malignant pleural effusions. Diagnosis was delayed due to the significant procedural barriers as a result of her small stature and microcephaly associated with her Angelman syndrome. Prompt multidisciplinary evaluation and alternative tissue acquisition were essential for diagnosis and treatment.