A 6-year-old, 4.5-kg, spayed Abyssinian cat presented with a 4-month history of progressive chin dermatitis.
The owner initially noticed black debris throughout the fur over the chin. During the next 4 months, hair loss developed as a result of the cat scratching the area. Initial prescribed treatment included application of a warm washcloth q12h and topical administration of benzoyl peroxide (2.5%), which appeared to cause clinical signs to worsen.
The cat was indoor only, up-to-date on vaccinations, and the only household pet.
Related Article: Skin Disease in Cats: It Isn’t Always What It Seems
On presentation, the cat was bright, alert, and responsive. There was some scarring over the right cornea from a previously healed ulcer. Comedones, dark keratinous debris, barbered hair, papules, erosions, and swelling were noted over the chin and lower lip; comedones and dark keratinous debris were also noted on the upper lip (Figure 1. Appearance of patient’s chin (A) and upper and lower lips (B) on presentation).
Skin scrapings were negative for demodectic mites. Cytologic examination of a papular lesion sample revealed coccoid bacteria with suppurative inflammation. Wood’s lamp examination and dermatophyte test medium sample were negative.
The patient was sedated with IM ketamine at 5 mg, dexmedetomidine at 0.03 mg, and butorphanol at 0.5 mg, along with local sedation of lidocaine; two 6-mm punch biopsy specimens with skin were obtained from the chin. Dermatohistopathologic examination revealed comedone formation, mild lymphoplasmacytic periductal inflammation with suppurative folliculitis, and intrafollicular coccoid bacteria.
1. What are the differentials for chin dermatitis in this patient?
2. What clinical signs are associated with this patient’s condition?
3. Where is the ideal site to obtain a punch biopsy specimen for diagnosis?
4. What dermatohistopathologic changes would be associated with this patient’s condition?
Diagnosis: Feline acne with secondary bacterial pyoderma
Related Article: Hair Loss in Cats
The cutaneous lesions were consistent with feline acne and secondary bacterial pyoderma and confirmed histologically (see Did You Answer?).
Inmany cases, feline acne is a straightforward diagnosis based on classic clinical lesions (see Clinical Presentations of Feline Acne). However, it is important to rule out demodicosis, ectoparasites, and dermatophytes as underlying causes.