case_images: PMC10867330_01
case_images: Preoperative MRI shows the soft tissue mass in the left arm. T1-weighted coronal image (A) shows patchy and irregular isointense signal lesion (yellow arrow). The soft tissue mass (yellow arrow) shows slightly high signal intensity on T2-weighted coronal (B) and axial (C) images and high signal intensity on T2 fat-suppressed axial (D) and coronal (E) images. 6-months postoperative MRI shows recurrence of left arm LGFMS after initial resection. Multiple nodules (yellow arrow) were detected in the extensor digitorium at the medial of the ulna, which exhibited high signal intensity on T2-weighted sagittal (F), T2 fat-suppressed sagittal (G) and coronal (H) images. The nodules (yellow arrow) demonstrate low signal intensity on T1-weighted axial image (I), high signal intensity on T2-weighted (J) and diffused (K) weighted axial images. Photomicrograph shows the alternating myxoid and fibrous area in the lesion (L) (HE, original magnification x 40). Higher magnification shows the spindle-shaped tumor cells arranged in bundles with uneven proliferation (M) (HE, original magnification x 200). FISH analysis of FUS detected both fused-and split-signals (N).
case_images: fmed-11-1172746-g001.jpg
case_images: PMC10867330_01_fmed-11-1172746-g001.jpg
case_images: fig1
case_images: T1-weighted image (Figure 1A) and high signal intensity on T2-weighted image (Figures 1B-E). The boundary of the lesion is not clear, with intermuscular edema (Figures 1A-E). Moderate cytologic atypia and up to 11 mitoses per 10 hpf in the most active part of the tumor were observed (Figures 1L,M). In situ hybridization (ISH) and fluorescence in situ hybridization (FISH) detected FUS gene rearrangement, which was consistent with the diagnosis of LGFMS (Figure 1N). Two months after the primary surgery, MRI revealed multiple subcutaneous and intermuscular soft tissue nodules in the left forearm (Figures 1F-K).
case_images: MRI after wide resections shows recurrence of left arm LGFMS. The mass in the extensor carpi ulnaris (thin yellow arrow) demonstrates high signal intensity on contrast enhanced T1 weighted sagittal image (A) and isointense signal intensity on T1-weighted sagittal (B) and axial (C) images. T2 fat-suppressed axial (D) and sagittal (E) images reveal high signal intensity in the mass (thin yellow arrow) and in the cavity of the left ulna with discontinuous cortical bone (thick yellow arrow). The nodule in the flexor digitorum profundus (yellow arrow head) demonstrates rim enhancement on contrast enhanced T1 weighted sagittal image (A) and mixed signal intensity on T1-weighted sagittal (B) and axial (C) images. T2 fat-suppressed axial image (D) reveals mixed high signal in the nodule (yellow arrow head). Images of contrast-enhanced MRI of the thoracic spine after wide resections show patchy high signal intensity in the T8, T11 vertebral body (F) (thin yellow arrows) and abnormal enhancement in T11 vertebral body and accessory (G) (thin yellow arrow). MRI after amputation shows chest wall metastases. T2 fat-suppressed axial (H) and sagittal (I) images reveal a mass with mixed signal intensity in the right back muscle (thin yellow arrow) and show discontinuous bone cortex of the adjacent right 7th rib with high signal intensity (thin yellow arrow).
case_images: fmed-11-1172746-g002.jpg
case_images: PMC10867330_01_fmed-11-1172746-g002.jpg
case_images: fig2
case_images: T8, T11 vertebral body (Figure 2F) and accessory of T11 (Figure 2G). To assess the patient's whole-body situation, 18F-flurodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) examination was further performed. MRI showed a mass in the right back muscle (Figure 2H) and the adjacent right 7th rib (Figure 2I).
case_images: Images of 18F-FDG PET/CT after wide resections and PET/CT after amputation. The MIP image (A) shows left forearm (red arrow) and T8, T11 vertebral body lesions (red arrow heads) with varying degrees of FDG uptake. The coronal (B) and axial (C) views of mass in the left forearm demonstrate increased metabolic uptake (red arrow; SUVmax 11.2). The sagittal image (D) demonstrates increased metabolic uptake in the T8 and T11 vertebral body (red arrow heads; SUVmax 3.3, 4.1), suggesting the presence of bone metastasis. The MIP image (E) reveals absence of the left forearm and lesions of the left stump (thin red arrow) and chest wall (thick red arrow) with varying degrees of FDG uptake. The axial (F) and coronal (G) views of the left stump demonstrate increased metabolic uptake at the extremity (thin red arrow; SUVmax 5.4). The axial image (H) reveals irregular thickening of the right chest wall with mildly increased metabolic uptake (thick red arrow; SUVmax 2.9).
case_images: fmed-11-1172746-g003.jpg
case_images: PMC10867330_01_fmed-11-1172746-g003.jpg
case_images: fig3
case_images: T11 vertebral body (SUVmax 3.3, 4.1) where slightly lower bone mineral density was observed (Figures 3A,D). Then, her left arm was amputated 5 cm above the elbow and the mass was about 10 cm from the incision, protruding from the skin with a necrosis surface. The histopathological characteristics of the tumor manifest similarities to those observed in prior recurrences. PET/CT revealed increased FDG uptake at the extremity of the left stump (SUVmax 5.4; Figures 3E-G), irregular thickening of the right chest wall and bone destruction of the adjacent right 8th rib (Figure 3H).