Fig. 2
Images of patient #3. A 6-year-old boy with a history of multiple recurrent desmoid-type fibromatosis (DTF) after surgery. Ultrasound images showed hypoechoic and fusiform enlargement of the left sciatic nerve in the middle of the thigh in both longitudinal sections (diameter: 1.2 cm) (A) and cross-sections (cross-sectional area 2.2cm2) (B). DTF was shown as an irregular solid lesion with heterogeneous internal echo at the side of the affected nerve (24 × 17 × 12 cm) (C). Recurrent DTF developed as a giant mass of the left lower limb (D, E). After two rounds of chemotherapy and six rounds of high-intensity focused ultrasound knife (HIFU) treatment, the patient underwent amputation surgery; note that the left sciatic nerve was markedly thickened with skeletal muscle tissue within nerve (F). Micrograph (H&E) of the cross-section of the affected sciatic nerve showed endoneurial intercalation of mature skeletal muscle fibers among the peripheral nerve fascicles and diagnosed neuromuscular choristomas (NMC) (G, H). NMC-DTF showed strong beta-catenin expression in immunohistochemical staining (I), and a CTNNB1 p. S45F mutation was identified