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*No consensus as to genesis
*No consensus as to genesis
*Cysts contain mucinous/yellow fluid
*Cysts contain mucinous/yellow fluid
*[[More on Ganglion cysts|More about ganglion cysts]]
More about ganglion cysts:
'''[Ganglion cysts in a juvenile dog. Cho K-O et al. Vet Path (2000) 37 340-3]'''
Ganglion cysts:
*Usually in close proximity to joints and tendon sheaths
*Extremely rare in veterinary medicine c.f. humans
*No consensus as to genesis
*Cysts contain mucinous/yellow fluid
*Wall composed of: inner myxomatous and outer
**Inner myxomatous areas
***Pleomorphic stellate and spindle cells within an abundant myxoid stroma
***Lined by fibroblasts on the inner aspect (although no true lining cells)
**Outer fibromatous areas
***Similar to granulation tissue
**Mitoses rare
*The base of all ganglion cysts in contact with the bone, with no boney destruction
*Mucin in the cavities stains blue with acid mucin and with AB-PAS
*EM
**Abundant rough ER and golgi and few mitochondria in the inner myxomatous cells and various stages of myxoid metaplasia
**Cells resemble both synovial cells and fibroblasts
**Small numbers of degenerative ganglion cells in the inner myxomatous lesions – marked dilation of rER and golgi; filopodia, multiple small vacuoles containing a dense granular material in the cytoplasm
**ECM – bundles of collagen fibrils adjacent in the fibroblasts in the initial phase of the mucinous lesions -> collagen fibrils broken and shortened and haphazardly arranged
*No communication with the synovial cavity and no synovial lining so not synovial cysts or adventitious bursa
*Cysts develop within the mucinous lesions surrounding a central collagenous core
*Synovial cells have two appearances on EM:
**Type A cells – phagocytic, contain numerous vacuoles, branched aperiodic fibrils, filopodia, vesicles, mitochondria
**Type B cells – adapted for protein production and contain abundant rER, few mitochondria, occasional vesicles and vacuoles
*Cells in the ganglion walls are similar to type B cells and fibroblasts
*Mucin probably produced by metaplastic fibroblasts
[[Category:Joints - Pathology]]
[[Category:Joints - Pathology]]