Sterile pyogranulomatous nodular panniculitis in a cat - case reportABSTRACT
Sterile nodular pyogranulomatous panniculitis is an inflammatory disease of variable extent and severity, considered uncommon in dogs and rare in felines. The aim of this study was to report the case of a feline with sterile nodular pyogranulomatous panniculitis responsive to pharmacological treatment. A male, mixed breed cat, weighing 4 kg, aged one year, was treated with a history of a single, ulcerated, erythematous, slightly irregular and firm nodule. Complete blood count, biochemical tests, cytology of the nodule, culture, radiography and histopathology were requested. The definitive diagnosis was obtained through histopathological examination and the established treatment, with prednisolone at a dose of 1 mg/kg, BID, for the first ten days, subsequently reduced to SID for another 10 days, associated with dipyrone 1 drop/kg, BID, for 5 days, was sufficient for the remission of the lesion. It is concluded that Sterile nodular pyogranulomatous panniculitis is a rare disease in felines, but important considering the wide diversity of differential diagnoses, and that in the case of a single nodular presentation, clinical treatment was sufficient for complete remission, and histopathology was the determining exam for diagnostic confirmation.
Keywords:
low caseload; dermatology; steatitis; felines
RESUMO
A paniculite nodular piogranulomatosa estéril (PNPE) é uma doença inflamatória variável em extensão e severidade, sendo considerada incomum em cães e rara em felinos. O objetivo deste trabalho foi relatar o caso de um felino com PNPE responsivo ao tratamento farmacológico. Foi atendido um gato macho, sem raça definida, 4kg, de um ano, com histórico de nódulo único, ulcerado, eritematoso, levemente irregular e de consistência firme. Foram solicitados hemograma, dosagens bioquímicas, citologia do nódulo, cultura, radiografia e histopatologia. O diagnóstico definitivo foi obtido por meio do exame histopatológico, e o tratamento estabelecido, com prednisolona na dose de 1mg-kg, BID, pelos 10 primeiros dias, posteriormente reduzido para SID por mais 10 dias, associados com dipirona uma gota/kg, BID, por cinco dias, o que se mostrou suficiente para a remissão da lesão. Conclui-se que a PNPE é uma doença rara em felinos, mas importante, tendo em vista a ampla diversidade de diagnósticos diferenciais. No caso de uma apresentação nodular única, o tratamento clínico foi suficiente para a remissão completa, e a histopatologia foi o exame determinante para a confirmação diagnóstica.
Palavras-chave:
baixa casuística; dermatologia; esteatite; felinos
INTRODUCTION
The sterile pyogranulomatous nodular panniculitis (SPNP) in felines is an inflammatory disease of the panniculus that results in the formation of nodular skin lesions, which can manifest as focal or generalized lesions, with intact, fistulous, or ulcerated appearances (Contreary et al., 2015), and its extent and severity may vary depending on each patient (Schissler, 2018). It has various names, such as panniculitis, steatitis, pansteatitis, granuloma syndrome, sterile pyogranuloma, granulomatous dermatitis, and sterile pyogranulomatous dermatitis, and it is associated with inflammation and necrosis of adipose tissue (Schissler, 2019; Steffl et al., 2020). This is a condition with low frequency in small animal clinics, considered uncommon in dogs and rare in cats (Rosa et al., 2018).
The etiology of panniculitis is not well understood; however, theories have been proposed to better comprehend its occurrence (Rosa et al., 2018). Panniculitis has been associated with nutritional disorders in cats, such as vitamin E deficiency, as well as the presence of infectious agents, immunological conditions, and other causes (Schissler, 2019; Steffl et al., 2020). Moreover, the development of panniculitis has been suggested as a possible consequence of underlying systemic diseases (Contreary et al., 2015). The clinical presentation of panniculitis involves an acute history of painful skin lesions, but without the occurrence of pruritus or malaise (Blume et al., 2015). The diagnosis is indeed challenging, requiring the exclusion of other differentials and subsequent laboratory exams confirmation (Schissler, 2019). The cause of the nodules and ulcers can be efficiently identified through cytology or may remain undefined, requiring histopathology, culture, and auxiliary diagnostics (Blume et al., 2015). It is also important to perform a differential diagnosis for other infectious causes before making a diagnosis (Contreary et al., 2015). The prognosis and remission of SPNP are favorable with immunosuppressive therapy and pain management (Schissler, 2019). The objective was to report the case of a feline diagnosed with sterile SPNP, responsive to clinical treatment with immunosuppressants.
CASE REPORT
A 1-year-old male mixed-breed cat, weighing 4kg, was examined with a history of a single, ulcerated, erythematous, slightly irregular, and firm nodule (Fig. 1A) located in the perineal region, which had been evolving for one month. During the physical examination, aside from the ulcerated nodule, only a temperature of 38.8°C was noted. The cat was then subjected to a complete blood count and biochemical tests to assess renal and hepatic function, with results within normal ranges for its species and age. Cytology of the lesion revealed the presence of an inflammatory infiltrate with degenerated neutrophils and lymphocytes, as well as adipocytes and free fat droplets (Fig. 1B), suggestive of panniculitis. A left latero-lateral (LLL) radiography showed an increased volume of soft tissues, approximately 3cm x 2.8cm in size, poorly defined, with mixed radiopacity in the hypogastric region of the subcutaneous tissue (Fig. 1C). Fungal and bacterial cultures showed no growth of clinically significant pathogens. Hematoxylin and eosin-stained histopathology revealed increased cellularity in the deep dermis and adipose panniculus, numerous neutrophils, lymphocytes, and plasma cells, pyogranulomas associated with lipocysts, and areas of fibrosis, characterizing pyogranulomatous nodular panniculitis. Treatment was initiated with prednisolone at a dose of 1mg/kg, BID, for the first ten days, then reduced to SID for another 10 days, along with dipyrone at 1 drop/kg, BID, for 5 days, and the use of an Elizabethan collar was recommended. Upon re-evaluation after 30 days, the animal showed complete remission of the nodule. The diagnosis of SPNP is based on the history, physical appearance of the lesions, cytology, culture, and antibiogram, but confirmation is established through histopathology. Treatment is simple and based on the use of immunosuppressive medications. The prognosis is favorable in cases of a single nodule. SPNP is a rare disease in felines, although it is easily treatable.
DISCUSSION
The description of sterile nodular panniculitis in this case is similar to previousy cases described in dogs (O’Kell et al., 2010); however, there are few reports of this pathology in felines (Blume et al., 2015; Steffl et al., 2020). The presentation of non-specific clinical signs poses a challenge for the accurate diagnosis of SPNP, and thus, it is necessary to conduct hematological and biochemical tests, cultures, cytology, radiography, and finally, histopathological examination to assist in making a definitive diagnosis (Rosa et al., 2018). The lesion presented in this report was characterized as nodular and singular, and the only clinical sign exhibited by the animal was a mild fever. Fine-needle aspiration (FNA) was performed along with cytological analysis of the aspirated material. Hematological and biochemical tests were within the reference ranges for the species and age. Bacterial and fungal cultures from the lesion showed no clinically significant growth, corroborating Silva et al. (2019), who reported a similar finding in a dog Steffl et al. (2020) in their research attempted to correlate vitamin E concentrations with the onset of panniculitis but did not obtain conclusive results, suggesting that further studies should be conducted to redefine serum vitamin E values in cats. Blume et al. (2015) reported the first case of pyogranulomatous panniculitis in cats caused by Nocardia nova, identified through 16S rDNA sequencing and phylogenetic analysis. Moreover, the animal showed laboratory abnormalities, such as leukocytosis due to neutrophilia with a left shift and toxic neutrophils on microscopic evaluation, unlike the present report where the animal showed no hematological changes. Silva et al. (2019) describes the use of radiography to assist in the surgical removal of nodules; in this case, radiography was used to assess the depth of lesion infiltration and to consider a potential surgical resolution if medical therapy was unsuccessful. Skin neoplasms, such as fibrosarcoma, fibroma, liposarcoma, and lipoma, could be considered differential diagnoses (Contreary et al., 2015) in this case, and cytological analysis helped rule out these neoplasms by suggesting SPNP through its cytological findings, which were later confirmed by histopathology. Silva et al., (2019) opted for the surgical removal of the nodules and achieved success, whereas in this report, therapeutic treatment was chosen, using prednisolone at a dose of 1 mg/kg BID for 10 days and then SID for another 10 days, totaling 20 days of treatment. The animal was in good health and free of recurrences at its last evaluation.
Pyogranulomatous nodular panniculitis in a one-year-old male mixed breed cat. A. A single nodule, ulcerated, erythematous, slightly irregular and firm in consistency. B. Inflammatory infiltrate with degenerated neutrophils and lymphocytes, along with adipocytes and free fat droplets. C. Lateral left (LLL) radiograph showing an increased volume of soft tissues, measuring approximately 3cm x 2.8cm, poorly defined, with mixed radiopacity in the hypogastric region of the subcutaneous tissue (white arrow).
CONCLUSION
It is concluded that SPNP is a rare but important disease in felines, given the wide range of differential diagnoses. In cases of a single nodular presentation, clinical treatment was sufficient for complete remission, and histopathology is the definitive test for diagnostic confirmation.
REFERENCES
- BLUME, G.R.; MARTINS, C.S.; MATTER, L.B.; VARGAS, A.P.C. et al. Pyogranulomatous dermatitis and panniculitis due to Nocardia nova in a cat. Ciênc. Rural, v.45, p.2019-2022, 2015.
- CONTREARY, C.L.; OUTERBRIDGE, C.A.; AFFOLTER, V.K.; KASS, P.H.; WHITE, S.D. Canine sterile nodular panniculitis: a retrospective study of 39 dogs. Vet. Dermatol., v.26, p.451-458, 2015.
- O’KELL, A.L.; INTEEWORN, N.; DIAZ, S.F.; SAUNDERS, G.K.; Panciera, D.L. Canine sterile nodular panniculits: a retrospective study of 14 cases. J. Vet. Intern. Med., v.24, p.278-284, 2010.
- ROSA, F.B.; OLDER, C.E.; MEASON-SMITH, C. et al. Analysis of bacterial and fungal nucleic acid in canine sterile granulomatous and pyogranulomatous dermatitis and panniculitis. Vet. Pathol., v.55, p.124-132, 2018.
- SCHISSLER, J. Sterile pyogranulomatous dermatitis and panniculitis. Vet. Clin. North Am. Small Anim.Pract., v.49, p.27-36, 2019.
- SILVA, A.S.; SANTOS, C.R.O.; CAMPINHO, D.S.P. et al. Paniculite nodular idiopática estéril em cão - relato de caso. Med. Vet., v.13, p.8-13, 2019.
- STEFFL, M.; NAUTSCHER, N.; KRÖPFL, A.; GRANVOGL, M. Nodular panniculitis in a cat with high alpha tocopherol concentration in serum. Vet. Med. Sci., v.6, p.980-984, 2020.
Publication Dates
-
Publication in this collection
14 July 2025 -
Date of issue
Jul-Aug 2025
History
-
Received
17 Oct 2024 -
Accepted
21 Feb 2025
