Kerion dermatophytosis in a Cocker spaniel
The following are cytological and histopathological specimens taken from a discrete 1.5cm alopecic cutaneous mass on the muzzle of a 10-month-old male Cocker spaniel.
Final Diagnosis
Pyogranulomatous furunculosis associated with intralesional fungal hyphae and spores typical of dermatophytosis (ringworm).
Discussion
Kerion dermatophytosis is an uncommon variant of canine ringworm in which the lesion is nodular and typically solitary, although multiple lesions may occur. It is most commonly associated with Microsporum gypseum however it can also occur with Trichophyton mentagrophytes and Microsporum canis infection. Fungal culture is required to differentiate although this may not always be successful in such lesions. Cutaneous nodules, which are essentially focal areas of furunculosis, most commonly occur on the face and forelegs, however any site may be affected. In the case of solitary lesions, surgical excision is typically curative.