PMC8175186_01
Anteroposterior radiograph of the right shoulder. The radiograph is normal.
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Plain radiographs were normal (Figure 1).
Ultrasonography of the right shoulder identified a hypoechoic nodular formation (yellow arrow) in the posterior deltoid, with approximately 8 x 10 x 13 mm in size.
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Ultrasonography of the right shoulder denoted a hypoechoic nodular formation in the point of tenderness, measuring 13 mm (Figure 2).
MRI images of the right shoulder. (a) Coronal images showing a nodular formation in the deltoid muscle (yellow arrows). The lesion is hypointense in T1 (left picture), but with strong enhancement with contrast (right picture). (b) Sagittal T2 image with turbo spin echo before contrast. The lesion appears as a hyperintense nodule (yellow arrow). (c) Axial (left) and sagittal (right) T1 images with fat suppression after contrast show a hyperintense well-limited lesion in the posterior deltoid (yellow arrows).
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Magnetic Resonance Imaging (MRI) confirmed the presence of a well-limited oval-shaped mass located in the posterior fibers of the right deltoid muscle, measuring 25 x 10 x 6 mm, which was hypointense in T1 and hyperintense in T2-weighted images and exhibited strong enhancement with contrast (Figures 3).
Intraoperative images. (a) Isolated tumor, primarily found in the substance of the deltoid muscle (yellow asterisk), with the tumor pedicle still intact (black arrow). (b) Resected lesion (125 mm scalpel handle with n 11 blade for scale).
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Surgical exploration identified a well-limited nodular lesion between the posterior fibers of the deltoid muscle, which was completely excised (Figures 4(a) and 4(b)).
Histological images of the removed tumor. (a) Well-limited proliferative lesion, with a rich vascular network (hematoxylin-eosin; original magnification x20). (b) Tumor formed by ovoid, epithelial cells, without signs of atypia and showing no mitoses (hematoxylin-eosin; original magnification x40). (c) Diffuse expression of smooth muscle actin (alpha-SMA) in the tumor (immunohistochemcial staining; original magnification x20 (right inferior corner photomicrograph) and original magnification x100 (larger photomicrograph)).
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These findings were compatible with the diagnosis of glomus tumor (Figures 5(a)-5(c)).