Malignant giant cell tumors of the tendon sheath of the right hip: A case report

Figure 1 Pelvis radiography. Multiple cystic hypodense lesions with variable sizes and well-defined borders were shown in the right iliac bone and right upper femur, suggesting osteolytic bone destruction.

Figure 2 Computed tomography of the pelvis reveals a soft tissue mass in the intermuscular space anterior to the right iliopsoas muscle and the right upper femur. A: The mass showed soft tissue density with lamellar hypodense necrosis inside; B: Osteolytic bone destruction of the right iliac bone was displayed clearly; C: The mass had poorly defined margins; and D: The massive tumor growed along the tendon.

Figure 3 Magnetic resonance imaging of the hip. A: Inhomogeneous moderate hypointensity on coronal T1-weighted images; B: Mixed mild hyperintensity on coronal fat-saturated T2-weighted images; C: Inhomogeneous hyperintensity on axial D-weighted images; and D: Heterogeneous mild ring enhancement of the lesion on sagittal T1-weighted images after contrast administration.

Figure 4 ^99mTc-methylene diphosphonate whole-body bone scan. Multiple high radioactive lesions were demonstrated along the right ilium, acetabulum and proximal femur, which were correlated with computed tomography and magnetic resonance imaging findings.

Figure 5 Histopathological images. A: Hematoxylin-eosin (HE) staining showed that the tumor was composed of mononuclear synovial-like cells and sarcoma cells. Lacunar-like lacunae were shown within the tumor cells and pleomorphism and heterogeneity of the tumor cells were obvious. Pathological nuclear division was seen and a collagen matrix was found between the cells (magnification ×100); B: Immunohistochemical staining revealed CD31 positivity (Envision, 100×); C: Immunohistochemical staining revealed CD34 positivity (Envision, 100×); D: Immunohistochemical staining revealed CD99 positivity (Envision, 100×); E: Immunohistochemical staining revealed Vimentin positivity (Envision, 100×); F: Immunohistochemical staining revealed INI-1 positivity (Envision, 100×); G: Immunohistochemical staining revealed TLE1 positivity (Envision, 100×); H: Immunohistochemical staining revealed CK positivity (Envision, 100×).

Figure 6 Computed tomography monitoring after chemotherapy. A-D: 1 mo and 7 d after the initial diagnosis; A: The lesion was larger in size than before and the adjacent abdominal wall was unevenly thickened; B: There were an increased amounts of necrosis lesions; C: The lesion invaded the acetabulum; D: Small and round solid nodules were found in both lung lobes; E-F: 5 mo and 20 d after the initial diagnosis; E: Thinning of the right abdominal wall with a skin fistula was caused by the mass; F: A patchy, hypodense infarcted area in the spleen represented a metastatic lesion; G: Further enlargement of the lesion; and H: Multiple osteolytic destruction was shown in the right ilium, acetabulum, and proximal femur.