Feline maculopapular cutaneous mastocytosis: a retrospective study of 13 cases and proposal for a new classification.

CASE SERIES SUMMARY: Cutaneous mastocytosis is a disorder rarely reported in veterinary dermatology and usually described as 'urticaria pigmentosa'. This study aimed to evaluate the diagnosis, treatment and outcome of 13 affected cats, selected from the files of a private referral dermatology practice within a period of 14 years. Breeds of the affected individuals included Sphynx (n = 9), Devon Rex (n = 2) and Sphynx/Devon Rex crossbreeds (n = 2). Females (n = 9) were over-represented and the median duration of clinical signs prior to diagnosis was 8 months. The clinical presentation of these 13 cats was compared with cases reported in the veterinary literature and classified according to the current human consensus on cutaneous mastocytosis. Three clinical forms could be distinguished in cats: (1) large papular lesions and wheals, typically localised to the head, shoulders, ventral neck and axillae, and which may spontaneously resolve (termed polymorphic maculopapular cutaneous mastocytosis); (2) erythematous dermatitis, characterised by small maculopapular lesions often associated with crusts and with a poorer prognosis (termed monomorphic maculopapular cutaneous mastocytosis); and (3) more chronic dermatitis characterised by lichenification and hyperpigmentation, similar to the human condition 'urticaria pigmentosa' (termed pigmented maculopapular cutaneous mastocytosis). Histopathology was performed in eight cases and revealed a superficial-to-deep dermatitis characterised by infiltrates of mast cells and eosinophils. The response to various treatments, including antihistamines, steroids and ciclosporin, was variable. RELEVANCE AND NOVEL INFORMATION: This article reports 13 new cases of feline cutaneous mastocytosis, confirming the clinical presentation and apparent breed predisposition. The feline maculopapular cutaneous mastocytosis seems to be clinically very close to the human form. This study proposes a new classification system for the feline disease based on the current human consensus, clinical presentation and prognosis, with three different subforms: polymorphic maculopapular cutaneous mastocytosis with eventual spontaneous regression; monomorphic maculopapular cutaneous mastocytosis with chronic evolution; and pigmented maculopapular cutaneous mastocytosis.

Urticaria pigmentosa-like disease in a dog.

Urticaria pigmentosa is a rare dermatologic syndrome in humans, cats, and dogs. This report documents a case of canine urticaria pigmentosa-like disease with unusual features and no C-kit mutation.

Maladie s'apparentant à l'urticaire pigmentaire chez un chien. L'urticaire pigmentaire est un syndrome dermatologique rare chez les humains, les chats et les chiens. Ce rapport documente un cas canin s'apparentant à l'urticaire pigmentaire comportant des caractéristiques inhabituelles et l'absence de mutation C-kit.(Traduit par Isabelle Vallières).

Dermatophytosis and papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis) in three Devon Rex cats.

UNLABELLED: PRESENTING SIGNS: Three Devon Rex cats were presented with multiple erythematous papules, occasionally associated with crusting and hyperpigmentation, with a linear distribution on the head, neck, chest and abdomen. One cat also had multifocal alopecia with hyperpigmentation on the dorsum. DIAGNOSIS AND TREATMENT: Clinical and histopathological features were suggestive of papular eosinophilic/mastocytic dermatitis (urticaria pigmentosa-like dermatitis). In all cases, dermatophytosis was diagnosed: in cases 1 and 2 there was histopathological evidence of dermatophytosis, while fungal culture was positive for Microsporum canis in cases 2 and 3. In all cats, lesions disappeared following antifungal treatment. CLINICAL SIGNIFICANCE: Papular eosinophilic/mastocytic dermatitis in Devon Rex cats may represent either an atypical presentation of dermatophytosis or a clinical and histological reaction pattern to various diseases, including dermatophytosis and allergic diseases. Clinical differentiation is crucial as there are important implications regarding treatment and, in particular, the use of glucocorticoids, which are contraindicated in cases of dermatophytosis.

Papular eosinophilic/mastocytic dermatitis (feline urticaria pigmentosa) in Devon Rex cats: A distinct disease entity or a histopathological reaction pattern?

A maculopapular eruption with clinical and histological features similar to those previously described in Sphinx cats under the name of urticaria pigmentosa is reported in five unrelated Devon Rex cats. Physical examination revealed erythematous, occasionally crusted papules, with a bilaterally symmetrical linear distribution on the latero-ventral trunk in two cases and a diffuse distribution on the ventral thorax in the other three cats. One cat also had a greasy seborrhoea on the head and dorsum. Pruritus and pigmented macules were present only in cats affected by secondary bacterial infection. Histological examination of papules in all cats and of the lesional skin of the cat affected by greasy seborrhoea revealed the presence of a perivascular to diffuse mastocytic and eosinophilic infiltrate in the dermis. The mean numbers of nondegranulated and degranulated mast cells per mm(2) were 303.2 and 451.6, respectively. The condition waxed and waned in all cats, and exacerbations were controlled with prednisolone or essential fatty acids.

Habronemic blepharoconjunctivitis in horses.

Habronemic blepharoconjunctivitis was characterized clinically by raised yellow gritty plaques in the palpebral and bulbar conjunctivae. Lid granulomas and blepharitis were observed in some cases. On histologic examination, mast cells, eosinophils, and collagenolysis was found in most sections, but if only one section was examined an erroneous diagnosis of mastocytosis could have been made. Treatment consisted of larvicidal mixtures for lid lesions and organophosphate ophthalmic drops along with corticosteroids for the conjunctivitis. If the cornea was damaged by the gritty conjunctival plaques, healing was more prolonged because corticosteroids were then contraindicated.

Generalized mastocytosis in a foal, resembling urticaria pigmentosa of man.

A newborn foal with multiple, nodular, cutaneous lesions containing mast cells and with mast cell accumulations in bone marrow was observed for 1 year. Cutaneous nodules grew to several centimeters in size, ulcerated, and regressed. Only a few healed nodules remained when the foal was 1 year old. The disease was considered to be similar to urticaria pigmentosa of man.