Cutaneous Intravascular Large B-Cell Lymphoma Presenting as Hemophagocytic Lymphohistiocytosis.

Intravascular large B-cell lymphoma (IVLBCL) is an uncommon and aggressive subtype of non-Hodgkin lymphoma defined by the proliferation of large malignant B cells confined within small blood vessels. This neoplasm can present with different nonspecific symptoms, including fever, altered mental status, livedoid skin rashes, hepatosplenomegaly, and cytopenias, often complicating its diagnosis. The main categories are classical (formerly designated as Western), hemophagocytic variant (formerly designated as Asian), and primary cutaneous IVLBCL. A distinctly severe manifestation is hemophagocytic lymphohistiocytosis (HLH), a hyperinflammatory syndrome characterized by exaggerated immune activation and macrophage activation manifested by phagocytosis of hematopoietic cells including neutrophils, red blood cells, and platelets. We describe a 72-year-old female who presented with features reminiscent of an autoinflammatory syndrome including fever and hyperferritinemia followed by clinical features concerning for HLH. She developed a reticulated skin rash. Following skin biopsy, a diagnosis was rendered of IVLBCL complicated by HLH. The pathophysiology and other aspects of the literature pertaining to IVLBCL and HLH are reviewed.