Unraveling the Complexities of Idiopathic Multicentric Castleman Disease and Its Multi-systemic Associations: A Case Report.

Castleman disease (CD) comprises a rare spectrum of disorders characterized by benign lymphoepithelial proliferation, classified into unicentric and multicentric forms. The idiopathic multicentric Castleman disease (iMCD) subtype, specifically, is challenging to diagnose and treat due to its variable manifestations and unpredictable disease course. We report a case of a 23-year-old female with a history of iron deficiency anemia presenting with concurrent antiphospholipid syndrome (APS) and human herpesvirus-6 (HHV-6) positivity. Investigations revealed a gastric mass, with a biopsy suggestive of the plasma cell variant of CD. This case report aims to understand the possible association of HHV-6 positivity with CD and the significance of diagnosing APS early in patients with the disease. Treatment with siltuximab and tocilizumab proved effective, highlighting the role of interleukin 6 (IL-6) in the elusive etiology of this condition.