Traumatic Rupture of Cystic Left Retroperitoneal Mass: An Atypical Presentation of Diffuse Large B-Cell Lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. Though the presentation is diverse, patients typically have a history of "B" symptoms and lymphadenopathy in areas such as the neck, mediastinum, or abdomen. However, a growing body of evidence suggests DLBCL can present as a cystic mass in diverse tissues. We present the case of a large cystic left retroperitoneal mass of unknown origin in a patient subsequently diagnosed with DLBCL. The diagnosis was obtained via percutaneous biopsy of the cystic mass in preparation for surgical excision. Upon diagnosis, surgical intervention was aborted, and the patient was started on chemotherapy treatment. However, four weeks into her treatment, she slipped and fell while in the bathroom and presented to the emergency department in shock with a computed tomography (CT) scan suggestive of splenic rupture. She underwent emergent splenectomy and resection of the cystic mass. She was discharged on postoperative day 7 and is currently continuing with outpatient chemotherapy. The presentation of DLBCL is notoriously diverse, however, this patient represents a unique presentation that adds to a growing body of literature suggesting DLBCL can present as a cystic mass. Pathological diagnosis should be obtained in all patients with cystic lesions of unknown origin before any surgical intervention to avoid unnecessary surgery and provide an optimal management plan.