Diffuse infantile fibromatosis is a rare condition affecting infants during the first 3 years of life. This condition is a multicentric infiltration of muscle fibers with fibroblasts resembling those seen in aponeurotic fibromas, presenting as lesions and tumors confined usually to the muscles of the arms, neck, and shoulder area Diffuse infantile fibromatosis is characterized by fast growing benign tumors. This disorder is known to be caused by mutations in germline variants, PDGFRB and NOTCH3, which may be generationally-inherited through autosomal dominant and recessive traits. Although diffuse infantile fibromatosis is classified as benign tumors, it can still lead to life-threatening complications and damage other organs.