Intravascular large B-cell lymphoma presenting as panniculitis

Intravascular large B-cell lymphoma (IVLBCL) is a rare disease with an incidence of less than 1 person per 1 million. It is a subtype of diffuse large B-cell lymphoma in which the lymphoma cells reside predominantly within the lumina of blood vessels (particularly capillaries) with circulating neoplastic cells detectable in the peripheral blood in less than 10%.1 Presenting clinical features are extremely variable. We describe a case of IVLBCL presenting as panniculitis. This case emphasizes the importance of collaboration between dermatology and pathology in considering rare but serious diagnoses when clinical features and histologic findings are discordant.