Cryptococcal granulomas of basal ganglia due to Cryptococcus neoformans in a cat: a case report and literature review

Abstract

A 3-year-old spayed female domestic short-haired cat presented with a head turning to the left, circling to the right, seizures, and opisthotonos for approximately one month. Neurological examination revealed a deficit in the postural reaction of the left limbs and visual abnormalities. Forensic computed tomography revealed a hyperattenuating round mass of 1.3 cm diameter with a hypoattenuating center in the right hemisphere. Histopathology showed multifocal granuloma lesions with the major mass mostly affecting the right basal ganglia. Cryptococcus neoformans variety grubii molecular type VNI/ST31 was isolated from the cryptococcal granulomas. This report highlights the epidemiological distribution and differential diagnosis of a feline central nervous system cryptococcosis caused by C. neoformans that occurred in an Asian country.

Keywords: Cryptococcus neoformans; basal ganglia; cat; central nerve system.

Fig. 1.

Transverse (A) and dorsal (B) reconstructed computed tomography (CT) images of the head in a brain window (window length, 40 HU, window width, 120 HU). The images show a large hyperattenuating mass with a hypoattenuating center in the right hemisphere. Decreased attenuation around the mass may be indicative of edema. The mean CT value at the periphery and center of the lesion was 64 and 46, respectively.

Fig. 2.

Postmortem examination of the serial transverse sections of intracranial cryptococcal granulomas lesions. The largest granulomatous lesion is predominantly observed throughout the right caudate nucleus, putamen, globus pallidus, and thalamus, with distortion and compression of the lateral ventricle and third ventricle. Additional lesions are mostly located at the junction of the left internal capsule and thalamus (black arrows).

Fig. 3.

Histopathology of the intracranial granuloma lesion. A: The unencapsulated mass compresses the right lateral ventricle and comprises pyogranulomatous foci containing amorphous eosinophilic material and necrotic debris. Hematoxylin and eosin staining. Bar=1 mm. B: Pyogranulomatous foci present as aggregates of foamy macrophages (black arrows) mixed with neutrophils, and plasma cells and lymphocytes are scattered at the edges of the mass (left), while abundant cryptococci (red arrows) are accumulated in the center of the mass (right) and present with negative staining with a halo. C: The image shows Cryptococcus organisms with positive periodic acid‒Schiff staining.