case_images: PMC10065854_01
case_images: In-phase (a) and out-of-phase (b) of T1-weighted (W) magnetic resonance imaging (MRI). A 12.5 x 6 x 6 cm soft tissue tumor was identified in the soleus muscle of an 88-year-old man. A relatively well-defined intramuscular mass reveals a signal drop on out-of-phase T1-WI compared to in-phase T1-WI, indicating the presence of fat components. (c) Gross findings of surgically excised specimen. Cut surfaces of an intramuscular tumor are gray tan in color and show extensive areas of geographic necrosis with foci of hemorrhage.
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case_images: PMC10065854_01_CRIPA2023-9443027.001.jpg
case_images: fig1
case_images: Magnetic resonance imaging revealed a 12.5 x 6 x 6 cm mass in the soleus muscle of the right lower leg, which showed heterogeneous signals suggestive of necrosis and hemorrhage (Figures 1(a) and 1(b)). Grossly, the tumor showed a solid gray tan-cut surface, nodular growth pattern, and central necrosis (Figure 1(c)).
case_images: Histological findings of the biopsy specimen. Magnification: x20. Epithelioid tumor cells are arranged in solid, cohesive sheets. Tumor cells exhibit round to oval nuclei with a relatively distinct nucleolus and abundant eosinophilic cytoplasm. These histological features are reminiscent of poorly differentiated carcinoma.
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case_images: PMC10065854_01_CRIPA2023-9443027.002.jpg
case_images: fig2
case_images: The biopsy specimen showed solid growth of epithelioid tumor cells with enlarged round or oval nuclei and abundant eosinophilic cytoplasm (Figure 2).
case_images: Histological findings of the surgical specimen. Magnification: (a, c-f) x20, HE, (b) x40. (a) An epithelioid tumor cell has well-developed staghorn-like (hemangiopericytoma-like) vasculature. (b) Pleomorphic multivacuolated lipoblasts are occasionally found. (c) Sudan III stain demonstrates fat droplets in the cytoplasm. (d) CAM 5.2 is focally expressed in epithelioid tumor cells. (e) The tumor nuclei are diffusely positive for GATA3. (f) S100 proteins are focally expressed in lipogenic tumor cells.
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case_images: PMC10065854_01_CRIPA2023-9443027.003.jpg
case_images: fig3
case_images: Histologically, most areas consisted of sarcomas with epithelioid morphology, as observed in the biopsy specimen (Figure 3(a)). In other areas, the tumor cells had a clear cytoplasm, some of which demonstrated multivacuolated cytoplasm, i.e., pleomorphic lipoblasts (Figures 3(b) and 3(c)). The epithelioid areas were focally positive for CAM 5.2 (Figure 3(d)) and diffusely and strongly positive for GATA3 (Figure 3(e)). Lipogenic areas showed the expression of the S100 protein (Figure 3(f)).