Nodular fascitis in the thigh followed up using ultrasonography

A 41-year-old woman noticed a mass on the inside of her right thigh in April 2003. Ultrasound examination revealed a mass measuring 18 mm × 10 mm × 10 mm in the subcutaneous fatty tissues. Its boundary was relatively clear, with rough edges. The interior of the lesion was hyperechoic and contained an irregular hypoechoic area in its center; a color Doppler sonographic examination detected no blood flow signals. Incision biopsy examination seemed warranted. Pathologically, the specimen showed a proliferation of fibroblast-like spindle-shaped cells but no atypical cells. Immunologic staining revealed that sections were positive to vimentin; negative to CD34, CD68, α-smooth muscle actin (α-SMA), and S-100 protein; and mildly positive to HHF35. These results led to a diagnosis of nodular fascitis. Nodular fascitis is not common, and few studies have described its sonographic characteristics. We therefore used ultrasound to follow up the patient and found that the lesion was markedly smaller 3 months after the first examination, at which time it was hardly discernible as a mass. Here we compare the ultrasound and pathologic findings, and report the results of a bibliographic study.