Intravascular Large B-Cell Lymphoma: A Diagnostic Dilemma

Intravascular large B-cell lymphoma is a rare malignancy characterized by the presence of lymphoma cells within the lumen of blood vessels. The annual incidence of cases is fewer than 0.5 cases per 1,000,000. It usually affects the elderly with an average age of diagnosis around 70 years. Due to the absence of lymphoma cells in the peripheral smear and lymphadenopathy, it is difficult to diagnose these cases. Although the central nervous system and skin are the commonly involved organs, they can involve any organ system. Prompt diagnosis and initiation of treatment are very crucial as it carries a high mortality. We describe two patients who presented with constitutional symptoms and fever of unknown origin, later diagnosed as intravascular large B- cell lymphoma. The diagnosis was difficult in both cases as the presenting symptoms were atypical. One of the patients was diagnosed at autopsy. The delay in diagnosis often leads to fatal outcomes as the disease is very aggressive. A high degree of clinical suspicion is the key to prompt diagnosis and improved outcomes.