[Electron microscopic study on synovial cysts]

Ganglion cysts in a juvenile dog

Ganglion cysts were diagnosed in a 4-month-old male Afghan Hound. Grossly, the subcutaneous ovoid cysts around the caudal right elbow joint and left ischiatic tuberosity had abundant mucinous fluid and internal folding. The lesions recurred twice around the elbow joint after surgical removal. Neither cyst communicated with the joint cavity. Histologically, the cyst wall consisted of inner myxomatous and outer immature connective tissue. Some parts of the cyst wall had various stages of myxoid metaplasia of collagen tissue leading to new cyst formation. Ultrastructural study revealed that cells in the myxoid metaplastic lesion had well-developed cytoplasmic secretory elements, including abundant rough endoplasmic reticulum, Golgi apparatus, and many smooth-walled vesicles. These ganglion cysts apparently resulted from the metaplasia of fibroblasts to secreting cells.

The intraosseous ganglion. A clinical-pathological report on 42 cases

In this study we report on the clinical, radiological and pathologic data of 42 intraosseous ganglia which had been verified histologically. Of the patients, 26 were male and 16 female. Their mean age was 41.8 years (range 20-71 years). Exclusively solitary ganglia were included in this study; mainly they were located within the lower extremity. In most cases (n = 12), the malleolus medialis was involved. In 40 patients, treatment consisted of curettage, in 39 cases in combination with autologous or homologous bone grafting. In 2 cases, a resection was performed. No local recurrence was observed. Etiology and pathogenesis are discussed.

Macrophage phenotype within simple ganglia

Immunohistological staining of the connective tissue stroma of simple ganglia using monoclonal antibodies demonstrated infiltrating mononuclear phagocytes. These cells were characterised by positive staining for the leukocyte common antigen, the monocyte associated CD14 phenotype and HLA-class II antigens. There was only occasional expression of an epitope associated with macrophage maturity, and of the iC3b receptor. No expression of the C3b receptor, the high affinity Fc receptor, the p150.95 adhesion molecule or the p8.14 molecule was observed. Polymorphonuclear leukocytes and lymphocytes were absent. The restricted epitope expression by the mononuclear phagocyte population of simple ganglia may be a reflection of the absence of other inflammatory cells and indicates that the micro-environment within inflammatory lesions such as subcutaneous rheumatoid nodules is very different to that present in ganglia.

A surface ultrastructure study of ganglia and digital mucous cysts

Three digital mucous cysts and three dorsal wrist ganglia were studied by light and scanning electron microscopy. Both exhibited the same findings, namely a porous network of collagenous fibers forming the wall and a fibrillated inner surface composed of a random arrangement of collagen fibers. An intermittent thin membrane was observed on the inner surface, but no evidence of a cellular lining was apparent. This anatomic study lends support to a shared cause.

[A contribution to the origin of ganglia. A study of light-, immunofluorescence-, and electronmicroscopic changes (author's transl)]

10 ganglia were studied by means of light and electrone microscope and with immunfluorescence methods. The light microscopic findings in the wall of a ganglion resemble on developing hygroma. The mesenchymal cells ultrastructurally show differentiation to synovia-like cells, either surrounding the ganglion in the connective tissue wall or lining the cavity. The development of synovial tissue from undifferentiated mesenchymal cells is due to the typical mechanical stimulus affecting joints.

Multifunctional mesenchymal cells resembling smooth muscle cells in ganglia of the wrist

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