Morfologia comparada da pitiose em cavalos, cães e bovinos

Abstract

Twenty-one cases of pythiosis involving horses (10), dogs, (nine) and cattle (2) were investigated. In all of them the etiology was confirmed through immunohistochemistry technique. Data related to clinical course, localization and macroscopic features of the lesions and cases closure were obtained from biopsies and necropsies protocols. For compared histomorphological and histochemical characterization, hematoxilin-eosin, Grocott‟s, Schiff periodic acid, sirius red and Grocott-Sirius red techiques were performed. The aspects analyzed were intralesional hyphal quantity, distribution and integrity, angioinvasive capability, Splendore-Hoeppli (SH) and inflammatory reactions inter-species. The equine macroscopic lesions were characterized by sole focally extensive wounds composed by abundant fibrous tissue surrounding yellowish, dense, firm and irregular branching coral-like masses (kunkers). Histologically, lesions consisted of well-collagenized connective tissue with multiple often coalescing areas of immature granulation tissue encircling coarsely round eosinophil cores (corresponding to kunkers). Dogs presented gastrointestinal and/or cutaneous lesions. The gastrointestinal ones usually consisted of transmural and segmental thickening of the organs walls and mesenteric tissue. Mesenteric lymph nodes were always involved. Cutaneous lesions consisted of ulcers in the lips mucocutaneous junction, masses in the thorax and prepuce and small nodules in chest, thorax and fore limbs. Two main patterns of inflammation were seen in dogs, alone or combined, independently of the tissue: one granulomatous/pyogranulomatous and another necro-eosinophilic. In cattle, cutaneous lesions were multiple and usually affected one or more limbs, ventral neck and sternum and, eventually, tail or muzzle. Microscopically, there were multifocal to coalescing discrete granulomas along with proliferated dermal collagen. The sirus red technique was quite useful to localize eosinophils in tissue and confirm the SH reaction nature, seen in the three species. Histomorphological aspects as quantity, distribution and integrity of intralesional hyphae, angioinvasive potential and the type of inflammatory and SH reactions seem to be implicated in the different kinds of lesions and clinical courses in different animal species suffering from pythiosis. Evidences that pythiosis cure is associated to granulomatous inflammation were observed.