PMC9051319_01
Transverse T2-weighted (left column) and pre- (middle column) and post-contrast T1W (right column) MRI images of a dog with extradural spinal epidermoid cyst; pre-operative (top row) and 2-month (middle row) or 28-month post-operative (bottom row) at the level of T9-T10 intervertebral disc space.
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F1
T9-T10 intervertebral disc space, filling ~60% of the cross-sectional area with associated marked spinal cord compression (Figures 1, 2, top row). T9-T10 intervertebral disc space with minimal spinal cord compression (Figures 1, 2, middle row). T10 vertebral body (Figures 1, 2, bottom row). The lesion was noted to be irregularly-shaped on T2 W images and ill-defined with T1 heterogeneous hyperintensity and no contrast enhancement. The rest of the MRI features remained unchanged from the previous scan including a persistent intramedullary T2 hyperintensity adjacent to the mass.
Transverse T2-weighted (left column) and pre- (middle column) and post-contrast T1W (right column) MRI images of a dog with extradural spinal epidermoid cyst; pre-operative (top row) and 2-month (middle row) or 28-month post-operative (bottom row) at the level of T10 vertebral body. The volume of the mass was reduced 2-month after surgery (middle column), but regrowth is observed 28 months post-surgery with progressive bone resorption and spinal cord compression (bottom row).
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F2
T9-T10 intervertebral disc space, filling ~60% of the cross-sectional area with associated marked spinal cord compression (Figures 1, 2, top row). T9-T10 intervertebral disc space with minimal spinal cord compression (Figures 1, 2, middle row). T10 vertebral body (Figures 1, 2, bottom row). The lesion was noted to be irregularly-shaped on T2 W images and ill-defined with T1 heterogeneous hyperintensity and no contrast enhancement. The rest of the MRI features remained unchanged from the previous scan including a persistent intramedullary T2 hyperintensity adjacent to the mass.
Histopathology low magnification (0.5 x objective): Cystic lesion. The biopsy specimen consists mainly of stacks of lamellar keratin (arrows) with only a few short segments of cyst lining (arrowheads). Hematoxylin and eosin stain; Bar = 1.5 mm.
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F3
Histologically, the surgical biopsy specimens included stacks of orthokeratotic lamellar keratin and a few 2-mm-long segments of keratinizing stratified squamous epithelium supported by fibrous tissue without adnexa (Figures 3, 4).
Histopathology high magnification (20 x objective): Segment of the cyst lining. The epidermis-like stratified squamous epithelium has thickened stratum spinosum (asterisk) and stratum granulosum (arrowhead) with orthokeratotic hyperkeratosis. Note the lack of hair follicles or adnexal glands in the underlying fibrous tissue Hematoxylin and eosin stain; Bar = 50 mum.
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F4
Histologically, the surgical biopsy specimens included stacks of orthokeratotic lamellar keratin and a few 2-mm-long segments of keratinizing stratified squamous epithelium supported by fibrous tissue without adnexa (Figures 3, 4).