Unusual case of diffuse connective tissue disease with nodule formations in muscle, lung, kidney and brain

A 9-year-old boy had nodular masses in the left gastrocnemius muscle and lung, right kidney and right frontal area of the brain. Laboratory examinations, including positive anti-nuclear antibody, anti-RNP antibody, RA and CRP, hyper-gamma-globulinemia and accelerated ESR, showed characteristic of diffuse connective tissue disease (DCTD). Biopsy specimens were obtained from the thymus and from masses in the left lung and gastrocnemius muscle. The thymus showed hyperplasia, and a mass in the lung showed nonspecific inflammatory reactions such as connective tissue proliferation and cellular infiltration. Biopsied muscle also showed severe connective tissue proliferation, cellular infiltration, variation in fiber size and thickened blood vessel walls. In addition, abnormalities, including thickening of the basement membrane and an almost occluded narrow lumen of capillaries, were found on electron microscopy examination. Steroid administration led to remarkable improvement of the symptoms. These results suggested that DCTD is responsible for these symptoms.