Idiopathic Multicentric Castleman Disease

Castleman Disease (CD) is a spectrum of heterogenous hematological diseases that share characteristic clinical, histopathological, and immunological features. We present a case of a 61-y female with history of non-Hodgkin Lymphoma and hypothyroidism presenting with fatigue, generalized weakness, nausea, and poor appetite. On admission, physical examination was unremarkable, and labs were notable for hyperkalemia, hyperuricemia and worsening renal function. Imaging showed lymphadenopathy in neck, mediastinum, and left axilla along with mediastinal and retroperitoneal lymphadenopathy. Initial work up of serum electrophoresis was suggestive of multiple myeloma however bone scan did not reveal any lytic lesions. As biopsy results were pending, patient developed worsening cytopenia’s and a repeat serum electrophoresis showed a M spike with IgG lambda against a polyclonal background. Bone marrow biopsy showed polytypic plasmacytosis that was negative for HHV 8 and lymph node biopsy also showed polytypic plasmacytosis. Further work confirmed the diagnosis of idiopathic multicentric Castleman disease and patient was treated with silutuximab and responded well.