Systemic sterile nodular panniculitis associated with an intra-abdominal mass in a dog

A 12-year-old spayed female dog was referred because of recurrent febrile syndrome and palpable abdominal mass. Ultrasonography and contrast-enhanced computed tomography showed a non-parenchymal abdominal mass. Multiple deep subcutaneous nodules with mixed fluid- and fat-attenuating centers were identified on computed tomography. Surgical exploration revealed that the mass was located near the tip of the left uterine horn. The mass was removed and the subcutaneous nodules were sampled for analysis. Histology together with negative microbial cultures indicated sterile pyogranulomatous steatitis of both subcutaneous and intra-abdominal lesions. The dog was diagnosed with a sterile nodular panniculitis with atypical involvement of intra-abdominal fat and was managed with long-term glucocorticoid treatment. Key clinical message: Computed tomography can be helpful for detecting clinically non-palpable subcutaneous nodules in dogs that are presented with recurrent febrile syndrome. These nodules may correspond to sterile nodular panniculitis, particularly if exhibiting a fluid and fat component. Detection should prompt sampling. This disease may not be limited to the subcutaneous tissues, and a systemic form should be considered, especially when additional clinical abnormalities are present.