Multicentric Castleman's Disease (MCD) is a rare and poorly understood disorder that straddles the intersections of hematology, oncology, rheumatology, and virology and can be fatal if improperly treated. The etiology of HHV8 negative disease is unknown and only isolated cases of associations with infectious agents have been reported in literature. However the co-occurrence of Mycobacterium cosmeticum with Castleman's disease has never been previously reported in literature. Hence we would like to report a case of Multicentric Castleman's disease with a coexisting M. cosmeticum infection. Keywords: Ulcerative colitis; Imageology; Hypoalbuminemia; FolliclesCase report 58 year old gentleman, a painter by profession, who gives a history of ulcerative colitis for the past six years, was evaluated in medical gastroenterology department of our institution in October 2016, for symptoms of progressively increasing abdominal distension and loss of weight for the past eight months [1].On clinical examination he had right cervical Level II Lymph node enlargement (2 × 1.5 cm) with moderate ascites and splenomegaly. All other systems were unremarkable on examination.At the time of initial presentation his laboratory investigations revealed hypoalbuminemia, with all other parameters within normal limits including ECHO scan. Biopsy from the cervical lymph node was suggestive of Castleman's disease (angiofollicular hyperplasia). On low power microscopy, an increase in the number of follicles in the cortex with the germinal