Pythium spp
From Felipedia
Pythiosis is a rare fungal disease of cats. Pythium insidiosum is an aquatic organism of the order Personosporales, found in the tropical and subtropical regions of the world. In the Unitred States, the organism is endemic in states bordering the Gulf of Mexico. [1].
Pythiosis in cats almost always is a cutaneous disease affecting the extremities, tail-head, perineum, and rarely, the face[2]. The lesions usually are hairless, proliferative, edematous and occasionally pruritic. Often spontaneous ulceration and serosanguineous exudate occur. Nasal and retrobulbar pythiosis (the most common form in dogs) has been seen in two domestic cats in addition to several large exotic cats, and disseminated pythiosis with central nervous system involvement was reported in one cat[3].
The diagnosis of pythiosis classically has been based on identification of the organism on cytological or histopathological specimens. The fungal hyphae are not numerous but sometimes may be seen as unstained, wide, poorly septate branching, 'ghost' hyphae amid the granulomatous cellular background in Wright's-Giemsa stained specimens. The associated inflammatory response to Pythium spp is often eosinophilic, so this would raise the suspicion for pythiosis.
The most effective treatment is complete surgical resection of affected tissue. Unfortunately, tissue invasion often is extensive by the time a diagnosis is made, Systemic anti-fungal agents have had little apparent beneficial effect in most patients with pythiosis, and the prognosis for recovery is poor.
