(495) Double-Hit Lymphoma Strikes the Heart: A Rare Case of Complete Heart Block

Introduction: Double-hit lymphomas (DHL) are a subtype of B-cell non-Hodgkin lymphomas with similar morphology to diffuse large B-cell lymphoma (DLBCL). Clinically, DHL presents with advanced disease stages and numerous organ involvement. Herein, we present a case of stage IV double-hit lymphoma in a middle aged female who presented with syncope and complete heart block.

Description: Middle aged female with no medical history presented initially due to syncope. She had a month-long history of cough, subjective fevers, rhinorrhea, and congestion and was recently treated for a spontaneous abortion 1 week ago. Notably, about 10 months prior she was seen for another spontaneous abortion but no ovarian masses were seen on transvaginal ultrasound then. She had signs of shock with severe lactic acidosis and ECG showed 3rd degree heart block and she was immediately upgraded to the ICU for pressure support and dual-chamber pacemaker placement. CT abdomen/pelvis showed bilateral heterogeneous ovarian masses, multiple enlarged abdominal lymph nodes, and pancreatic lesions. Echocardiogram revealed ejection fraction 70-75% with a right atrial mass. Lymph node biopsy revealed stage IV double-hit lymphoma. She was started on chemotherapy and intrathecal methotrexate with complete remission on her 5th cycle.

Discussion: Most DHL cases manifest in extranodal sites such as bone marrow, peripheral blood, gastrointestinal tract, bones, and occasionally the central nervous system, with involvement of reproductive organs being uncommon. Even rarer are instances of cardiac involvement, presenting as exophytic masses in the right atrium. Due to recent pacemaker placement, our patient could not undergo an MRI to determine etiology of her cardiac mass or rule out infiltrative disease. This case is a very rare instance of a DHL causing complete heart block. Thus, malignancy needs to be in every differential. Our patient underwent an extensive negative autoimmune and infectious workup. Delaying biopsy or malignancy workup in a patient with complete heart block in search other causes can lead to significant delays in treatment. Especially in the case of double hit lymphoma which has an extremely aggressive course with very poor prognosis if left untreated.