We herein report a 65-year-old man with elevated serum IgG4 levels, enlarged thyroid, and renal dysfunction, mimicking IgG4-related disease (IgG4-RD). The definitive diagnosis of IgG4-RD was not established because a tissue biopsy revealed no IgG4-positive cell infiltration or fibrosis. ⋯ The κ/λ ratio was >100, tumor plasma cells were present at >20% in bone marrow, and immunostaining revealed IgG4-positive plasma cells; therefore, he was diagnosed with IgG4-type MM. Patients with elevated IgG4 levels with no significant mass lesions should undergo systemic examinations to exclude malignancy.
Masashi Funada, Kazuhisa Nakano, Hiroko Miyata, Aya Nawata, and Yoshiya Tanaka.
The First Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Japan.
Intern. Med. 2020 Jan 1; 59 (5): 711-714.
AbstractWe herein report a 65-year-old man with elevated serum IgG4 levels, enlarged thyroid, and renal dysfunction, mimicking IgG4-related disease (IgG4-RD). The definitive diagnosis of IgG4-RD was not established because a tissue biopsy revealed no IgG4-positive cell infiltration or fibrosis. The presence of an M peak in the β fraction, Bence Jones protein in urine, and progressive anemia suggested multiple myeloma (MM). The κ/λ ratio was >100, tumor plasma cells were present at >20% in bone marrow, and immunostaining revealed IgG4-positive plasma cells; therefore, he was diagnosed with IgG4-type MM. Patients with elevated IgG4 levels with no significant mass lesions should undergo systemic examinations to exclude malignancy.