Pathomorphological aspects of cryptococcosis in domestic cats

O. Shchebentovska; K. Oriekhova; H. Blishсh

doi:10.15421/0225192

O. Shchebentovska Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies
K. Oriekhova Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies
H. Blishсh Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies

Keywords: basidiomycetous fungi, cat, skin, fine-needle biopsy, histopathology.

Abstract

Cryptococcosis is one of the most common mycotic infections in cats, which may affect the skin, mucous membranes of the upper respiratory tract, lungs, and central nervous system. Despite its high prevalence among cats in North America, Australia, and sporadic occurrence in Europe, there is no available information in Ukraine presenting case analyses of cryptococcosis in various animal species, likely due to the absence of timely diagnostic procedures for this disease. The etiological agents are Cryptococcus neoformans or C . gattii – encapsulated yeast-like fungi capable of surviving for prolonged periods in the environment, particularly in soil and avian excrement (especially th at of pigeons). Infection typically occurs through the aerogenic route. The nasal cavity is the most common site of the primary infection, with possible hematogenous dissemination to the skin, eyes, and central nervous system. This article describes two cases of cryptococcosis in non-pedigree domestic cats that were treated at a veterinary clinic in Lviv (Ukraine) during 2024. According to the anamnesis, both cats were males, aged 5 and 7 years, kept indoors with free outdoor access. Rapid tests for FIV and FeLV were negative. Clinical examination of one cat revealed a solitary, firm, alopecic, left-sided cutaneous nodular lesion near the nasal wing, while the second cat presented with inspiratory dyspnea and mucopurulent nasal discharge. Cytological and histopathological examinations were performed for diagnostic verification. Fine-needle aspiration biopsies were collected from the affected skin area near the nasal wing and from the nasal mucosa, followed by hematoxylin and eosin staining. To improve yeast visualization, the PAS reaction, Heidenhain’s Azan trichrome stain, and Grocott’s methenamine silver stain were performed. Cytological smears stained with Romanowsky-Giemsa revealed numerous round cells forming clusters located among epithelial and leukocytic cells. Cryptococcus spp. cells possessed a well-defined capsule. In the PAS (McManus) reaction, the yeast cells stained bright red and were surrounded by a thick mucoid capsule. Application of Grocott’s staining method clearly identified budding yeast cells, which appeared black in color. Thus, classical morphological features of cryptococcosis in domestic cats were identified through the use of cytological and histological diagnostic methods, once again emphasizing the importance of comprehensive morpholo g ical diagnostics for this infection.

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