case_images: PMC11155668_01
case_images: Upper left: Ventrodorsal radiograph of the cervical region: The mineralized lesion is close to the left transverse process of C5 (red arrow), with the blunted tip of the transverse process appearing to mold around the mineralized lesion. Upper right and lower images: T2W, T1W (lower left), and T1W + C (lower right) transverse MRI images: An angular structure is seen in the soft tissues lateral to the left side of the C5 vertebra. This has a signal void thin margin with the appearance of bone cortex and a core that is isointense to bone marrow (red arrow). The surrounding soft tissues are heterogeneous. Note also how there is a large area of surrounding soft tissue swelling cranial to the left shoulder (blue star).
case_images: fvets-11-1335175-g001.jpg
case_images: PMC11155668_01_fvets-11-1335175-g001.jpg
case_images: fig1
case_images: On radiographs, an irregularly marginated, angular mineral opacity was located adjacent to the left transverse process of the fifth cervical vertebra (Figure 1). Some contrast enhancement was noted in the muscle surrounding the mineralized structure, and further enhancement was noted in the right (dependent) aspect of the fluid pocket (Figure 1).
case_images: (A) Removed bony structure. (B) Post-surgical ventrodorsal radiograph of the cervical region with a small amount of residual tissue suspected incomplete lesion capsule removal (red ellipse and arrow).
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case_images: PMC11155668_01_fvets-11-1335175-g002.jpg
case_images: fig2
case_images: It was firm and gritty to cut (Figure 2A). Post-surgery radiographs detected a dense residual tissue (suspected to be the rest of the firm capsule), confirming that HO had probably not been completely removed (Figure 2B).
case_images: Representative photomicrographs of the heterotopic ossification stained with hematoxylin-eosin (A) and Giemsa (B). The mass presents well-differentiated bone spicules (BS) and is confined by a periosteum-like pseudocapsule (PC). Toward the endosteal compartment, there is a layer of osteoblasts (OB). The newly formed bone further contains hematopoietically active bone marrow (BM), interrupted by fat vacuoles. The scale bars indicate the level of magnification. HE: hematoxylin-eosin; Gie: Giemsa.
case_images: fvets-11-1335175-g003.jpg
case_images: PMC11155668_01_fvets-11-1335175-g003.jpg
case_images: fig3
case_images: The morphological diagnosis was an intramuscular, mature HO with vascular hamartoma (Figure 3).
case_images: Ventrodorsal radiograph of the cervical region with a small osseous lesion after 2 years from the surgery (red ellipse).
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case_images: PMC11155668_01_fvets-11-1335175-g004.jpg
case_images: fig4
case_images: Two years later, an osseous lesion of 8 mm in size was detected on routine follow-up radiographs at the surgery site; however, there were no associated clinical signs (Figure 4).