Banca de DEFESA: PAULA DIAS RETAMERO

Anatomopathological evaluation and retrospective study of granulomatous/pyogranulomatous dermatitis diagnosed in dogs and cats at the Pathological Anatomy Sector at UFRRJ (1994 to 2022)

dermatopathology; canine,; feline

Dermatopathies are common in clinical practice with small animals, representing 25% to 75% of cases. Among these conditions are granulomatous and pyogranulomatous dermatitis, caused by various etiological agents, including sporotrichosis, a zoonosis of great relevance to public health. The objective of this work was to carry out a retrospective study and describe the anatomopathological aspects of dermatitis classified in the Laboratory of the Pathological Anatomy Sector (SAP) of the Federal Rural University of Rio de Janeiro (UFRRJ) from 1994 to 2022 as granulomatous or pyogranumatous in canine and feline species, with the purpose of identifying the most common causative agents of these dermatitis, in addition to evaluating the epidemiological and lesion presentation patterns. Data from the SAP file were collected and tabulated, hematoxylin and eosin (HE) staining was performed, in addition to periodic acid-Schiff (PAS) and Grocott silver histochemical techniques. Additionally, fungal culture and real-time polymerase chain reaction (qPCR) were performed, with extraction from phenol and chloroform, for Sporothrix brasiliensis, S. schenkii and S. globosa in cases diagnosed in dogs. 92 cases were described in dogs and 32 in cats and sporotrichosis was the most common cause in both species, representing 21.74% (20/92) of cases in dogs and 56.25% (18/32) in cats. Among the dogs diagnosed, 35% (7/20) were mixed breed, 25% (5/20) were Pitbull and 20% (4/20) were Poodle. The average age was 6 years, with 55% (11/20) males and 45% (9/20) females. The main locations observed were 50% (10/20) in the nasal bridge and 20% (4/20) in the cervical region. In the microscopic analysis, 50% (10/20) presented a diffuse pattern, 80% (16/20) were accentuated. All cases (100%, 20/20) showed macrophages, with 95% (19/20) showing marked intensity. Furthermore, neutrophils were also observed in all cases and, in 90% (18/20), pyogranulomatous inflammation was markedly intense. Of the cases diagnosed as canine sporotrichosis, 15% (3/20) were considered suggestive, with yeast-like structures observed on HE staining. Furthermore, 50% (10/20) showed yeast in PAS histochemistry and 50% (10/20) in Grocott histochemistry. Definitive diagnosis by culture was carried out in 27 animals and 13 were positive for the Sporothrix schenkii Complex. qPCR was performed on 78 paraffin blocks of confirmed or suspected cases of sporotrichosis in dogs. Among the cats diagnosed with sporotrichosis, 100% (18/18) were mixed breed, 66.67% (12/18) males and 33.33% (6/18) females, with an average of 4 years of age. The lesions were mainly located on the nasal bridge in 33.33% (6/18) of cases, followed by 16.67% (3/18) on the eyelid. In the microscopic analysis, 55.56% (10/18) of the lesions showed a multifocal inflammatory pattern and 83.33% (15/18) were accentuated. In all cases (20/20), macrophages and neutrophils were observed as the main inflammatory components, with 44.44% (10/18) showing marked intensity; 72.22% (13/18) of cases diagnosed in HE, 88.89% (16/18) in PAS and 44.44% (8/18) in Grocott. The study highlights the relevance of sporotrichosis, which is a disease described as epidemic in Brazil and hyperendemic in Rio de Janeiro, and was the most frequent cause of granulomatous and pyogranulomatous dermatitis, caused by infectious agents in dogs and cats, in addition to the need to use techniques complementary to hematoxylin and eosin for a more accurate diagnosis. Furthermore, extracting DNA from paraffin material presents significant challenges, mainly due to the action of formaldehyde and exposure time, factors that can compromise the quality of the genetic material and make it difficult to apply this complementary diagnostic method with satisfactory precision.