PMC9512598_01
MRI (a) axial T1 WI nonfat saturated demonstrates mild hyperintensity compared to skeletal muscles. (b) Axial T2 WI with fat saturation demonstrates marked homogenous hyperintensity. (c) Axial subtraction image (pre- and post-IV gadolinium contrast) T1 WI with fat saturation confirms the homogeneous avid enhancement. (d) Axial T1 WI with fat saturation, precontrast demonstrates mild hyperintensity compared to skeletal muscles. No fat signal suppression. (e) Coronal T1 WI with fat saturation, post-IV gadolinium contrast injection demonstrates homogeneous avid enhancement.
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fig1
MRI showed a well-defined oval shaped soft tissue mass in the superficial subcutaneous tissue of the right proximal thigh (Figure 1).
The tumor grossly shows fleshy gray cut surface with well-circumscribed round edges (a). Histological examination shows nested pseudoalveolar proliferation of histiocytes and synoviocytes showing abundant eosinophilic cytoplasm with some perinuclear hemosiderin (H&E, (b) -100x and (c) -200x). Scattered multinucleated osteoclast-like giant cells are seen (H&E (c) -200x, arrow). The tumor shows atypical cytological features in the form of atypical mitotic figures (H&E (d) -400x, arrow). The neoplastic cells are diffusely positive for immunohistochemical stain for clusterin antibody (clusterin IHC, (e) -upper right insert).
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fig2
Our initial impression was benign diffused type tenosynovial giant cell tumor (Figure 2).