First case report of cutaneous sporotrichosis (Sporothrix species) in a cat in the UK

Abstract

Case summary: A 12-year-old female neutered indoor-outdoor domestic longhair cat presented with frequent sneezing and a nodular, suppurative lesion on its dorsal nose. Histopathological examination revealed a fungal granuloma. PCR and sequencing of the ribosomal internal transcribed spacers (ITS) regions (ITS-F and ITS-R) confirmed an infection with a Sporothrix species. Further sequencing of the beta-tubulin and calmodulin genes confirmed Sporothrix humicola, which lies within the Sporothrix pallida complex. The cat had concurrent diabetes mellitus, which responded to insulin therapy and diet. Oral itraconazole at 10 mg/kg PO q24h resulted in resolution of the lesions after 12 months. Treatment was well tolerated.

Relevance and novel information: This is the first report of sporotrichosis in a cat in the UK and only the fifth worldwide involving the S pallida complex. Clinicians, pathologists and microbiologists need to be aware of the potential of Sporothrix infections in the UK and the ability of S pallida complex to cause opportunistic infections. Molecular techniques can achieve rapid and accurate identification of rare fungal organisms. A precise diagnosis with molecular testing can provide information regarding prognosis, treatment and zoonotic implications.

Keywords: Cutaneous mycosis; Sporothrix pallida; Sporothrix species; molecular identification; sporotrichosis.

Figure 1

(a) The cat shortly after presentation with a large suppurative nodule on its dorsal nose (the sutures were used to close the incisional biopsy site). (b) Complete resolution of the cutaneous lesions with only residual scarring at the biopsy site after 12 months of itraconazole treatment (10 mg/kg PO q24h)

Figure 2

Indirect impression smear cytology of the cutaneous lesion showing oval encapsulated bodies (a), some of which have been phagocytosed by macrophages (b) (Rapi-Diff II stain, × 400 magnification)