Spontaneous multicentric myxoma of the dermal nerve sheaths in farmed European eels Anguilla anguilla.

This report describes a peripheral nerve sheath tumour in 8 European eels Anguilla anguilla L. from a fish farm located in Croatia. The newborn tissue appeared as smooth and soft skin nodules without pronounced colour change. Nodules were dome-shaped with a pale crater and were present on different body areas. In general, nodules were located as series of differently sized protrusions extending along the lateral line on both sides of the fish, as well as sensory canals on the head. Cut sections showed a homogeneous, pale white-grey texture. Histologically, the pathological tissue was located in the dermis, occasionally intruding into the hypodermis, and pushing as a space-occupying mass against the underlying muscle tissue without any evident boundaries. The pressure also caused changes in the overlying epidermis, such as atrophy, spongiosis and erosion. In some areas, the epidermis was 1 cell thick and club and goblet cells had completely disappeared. Ultimately, these changes resulted in shallow ulceration. Tumour tissue was characterized by a scant population of spindle or stellate cells, with oval, hyperchromatic nuclei and pale cytoplasm embedded in a copious myxoid matrix. Cells were arranged in fascicles and whorls, extending in a poorly defined manner among the dermal collagen bundles. Occasionally, adipose cells were also detected, mainly in the central portion of the bulges. Myxoid areas appeared rich in metachromatic and alcianophilic mucous ground substance. Reticular fibres and collagenous connective tissue were scarce. Immunohistochemistry (IHC) using antibodies against S-100 and glial fibrillary acidic protein caused a slight positive reaction in neoplastic dendritic cells. High magnification showed the immunostaining to be cytoplasmic in all tumour cells. IHC with anti-calretinin antibody gave only negative results. Macroscopic, histological, histochemical and immunohistochemical findings were consistent with a diagnosis of multicentric myxoma of the dermal nerve sheaths, a tumour not yet reported in fish.

Radical surgical resection of locally invasive oro-cutaneous tumors in the buccal region of 2 horses.

OBJECTIVE: To report treatment and wound healing after radical surgical mass excision in the equine buccal region. STUDY DESIGN: Clinical case reports. ANIMALS: An 11-year-old Warmblood gelding and a 9-year-old Norwegian Trotter gelding. METHODS: Large tumoral masses were removed from the buccal region by radical electrosurgery, creating large defects into the oral cavity. Wound ultimately healed by second intention. RESULTS: Buccal defects in both horses healed well by second intention without tumor recurrence. CONCLUSIONS: Locally invasive tumors involving the cheek region of the horse can be successfully treated by radical electroexcision alone, creating transmural defects up to 14 cm length x 8 cm height. CLINICAL RELEVANCE: Large transmural defects in the cheek region of the horse, formed by radical surgery can heal satisfactorily by second intention healing without undue discomfort to the patient or major complications.