Introduction Intravascular large B-cell lymphoma is a rare subtype of diffuse large B-cell lymphoma with an estimated frequency of less than one percent of all lymphomas. It has a variety of presentations and is known as “the great imitator” as it may mimic other conditions. It has a fulminant course with high mortality if left untreated.  

Case Presentation Discussion 
We report a 65-year-old male who presented with exertional dyspnea, dry cough, and hoarseness of a few days. Work-up did not reveal any specific condition or lesion in the cardiopulmonary systems. He developed worsening pancytopenia within one week, underwent a bone marrow biopsy, and was found to have intravascular diffuse large B cell lymphoma with hypertetraploidy (karyotype XXYY). His symptoms improved after one cycle of chemotherapy. Bone marrow biopsy after six cycles of chemotherapy showed no evidence of lymphoma and a normal karyotype. Intravascular large B-cell lymphoma is a type of extranodal large B-cell lymphoma where growth is restricted to the Lumina of vessels. It is a rapidly fatal malignancy when diagnosis and treatment is delayed. There are two forms: the Western form presents with skin, neurologic findings and lymphadenopathy, and the Asian form presents with fever, anemia, thrombocytopenia, hepatosplenomegaly, 
bone marrow invasion, respiratory disturbance and disseminated intravascular coagulopathy. Our patient presents as a hybrid of both variants despite being of 
Western origin.