IgG4-related Disease Involving Multiple Organs with Elevated Serum Interleukin-6 Levels.

: A 63-year-old woman presented to our hospital with elevated levels of serum IgG4, marked wall thickening of the gallbladder, hepatomegaly, and abdominal lymphadenopathy. She experienced a recurrent fever and leg edema. Her laboratory data demonstrated anemia, hypoalbuminemia, and elevated serum levels of interleukin-6 and C-reactive protein. The patient was eventually diagnosed with IgG4-related disease according to the comprehensive diagnostic criteria, although the patient exhibited common clinical manifestations of multicentric Castleman disease such as a fever, anemia, lymphadenopathy, and elevated levels of serum interleukin-6 and C-reactive protein. This case report highlights the difficulties in differentiating between these two diseases.