PMC10067867_01
Multimodal ultrasonographic assessment of the mass. (A) Long-axis ultrasound showing a hypoechoic mass located deep in the pectoralis major muscle; it was deep in the gland and the upper right breast. (B) The adjacent glands appear blurred. (C) Virtual touch tissue imaging and quantification mode. The depth is 2.4 cm, median speed 6.06 m/s, and mean speed 6.18 m/s. The surrounding muscular layer is 2.72 m/s. (D) Qualitative contrast-enhanced ultrasound results. (E) Time-intensity curve.
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The ultrasonography revealed a solid hypoechoic mass that measured approximately 18 x 21 x 12 mm in the muscular layer of the chest wall ( Figure 1A ). The boundary of the mass was blurred ( Figure 1B ). Quantitative analysis using virtual touch quantification showed a mean shear wave speed of 6.18 m/s ( Figure 1C ). The qualitative CEUS results demonstrated an uneven high enhancement in the entire mass, annulus eccentricity enhancement, and a "dark star" sign ( Figure 1D ). The quantitative analysis of the CEUS images was conducted using the SonoLiver  Software, which showed a rapid enhancement ( Figure 1E ).
(A) Microscopy showing dense granular cells that are diffusely distributed, as well as infiltration and growth of the granular cells between the muscle fibers, with no clear separation between the cells and the muscle fibers (Hematoxylin and eosin [H&E] staining, x400). (B) S-100. The cytoplasm of the tumor cells is brownish yellow, indicating strong positive staining (immunostaining, x400).
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Postoperative pathology confirmed the presence of a GCT ( Figure 2 ).
PMC10067867_02
(A) Ultrasound showing a hypoechoic subcutaneous mass in the left axilla with an aspect ratio greater than one and acoustic shadowing. (B) Color Doppler shows no obvious blood supply in the mass. (C) Acoustic radiation force impulse model. (D) In the arterial phase, the tumor is slightly enhanced in the periphery, but not in the interior.
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Subsequently, the patient underwent ultrasonography revealing a solid subcutaneous soft tissue mass of approximately 13x9x15 mm in the axilla, with unclear boundaries, irregular shape, and an aspect ratio greater than one ( Figure 3A ). Color Doppler ultrasonography demonstrated a lack of blood vessels in the mass ( Figure 3B ). The ultrasound elastography revealed a hard-textured mass ( Figure 3C ) and contrast-enhanced ultrasonography indicated low enhancement in the peripheral part of the mass but no enhancement in the interior during the two minutes of continuous observation ( Figure 3D ).
(A) Microscopic subcutaneous growth of infiltrative platelet-like growths of granulosa cells and vacuolated adipocytes are shown (Hematoxylin and eosin [H&E] staining, x200). (B) In the fibrous septa, nest-like unencapsulated granulosa cells are also seen (H&E staining, x400). (C) S100 cytoplasm showing diffuse and strong positivity (immunostaining, x400). (D) CD68 weak positivity (immunostaining, x400).
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While postoperative paraffin section examinations confirmed the diagnosis of GCT ( Figure 4 ), tumor metastases were not found in the lymph nodes.