Intrapancreatic accessory spleen mimicking pancreatic insulinoma with intrapancreatic metastasis in a cat

Intrapancreatic accessory spleens in African swine fever infection of wild boar (Sus scrofa)

Intrapancreatic accessory spleen (IPAS) is one of the most frequent congenital splenic anomalies in humans; however, studies in veterinary medicine are scarce. This study aimed to describe the macroscopic, histopathological and immunohistochemical features of 11 suspected cases of IPAS in wild boar piglets of 3-4 months old. Seven of the 11 animals were immunised with a low virulence isolate of African swine fever virus (ASFV) and subsequently challenged with a highly virulent ASFV isolate (LVI-HVI group). The remaining four animals were exclusively infected with a highly virulent isolate of ASFV (HVI group). Grossly, lesions comprised focal or multifocal reddish areas of variable shape, located on the surface of the pancreatic tail or within the parenchyma. Histological and immunohistochemical studies (anti-CD79 and CD3) confirmed the presence of IPAS in eight of the 11 cases. IPAS shared the same histological structure and alterations as those observed in the original spleen. The immunohistochemical study against ASFV revealed the presence of VP72+ cells in both the spleen and IPAS of seven of the eight piglets. The results of this study describe for the first time the presence of IPAS in ASFV infection of wild boar (Sus scrofa) regardless the isolate and suggest that the infection may induce the development of ectopic splenic tissue due to an increased demand for phagocytic cells from the reticuloendothelial system. However, further studies are needed to understand the immunological mechanisms that trigger the formation of these accessory organs.

Ultrasonographic and colour Doppler features of intrapancreatic splenic tissue in a cat

Case summary

A 2-year-old female neutered domestic longhair cat was referred for a 3-day history of lethargy and anorexia. Physical examination documented abdominal distension and pain, which, alongside marked electrolyte imbalances on blood biochemistry, was highly suspicious for a gastrointestinal obstruction. This was confirmed on diagnostic imaging, with abdominal ultrasonography also identifying an incidental, well-defined small lobular hypoechoic nodule adjacent to the tail of the spleen, with high vascularity on Doppler interrogation. This was identified as a focal nodule at the tip of the left limb of the pancreas at surgery, and resected via partial pancreatectomy. Histopathological examination confirmed intrapancreatic splenic tissue.

Relevance and novel information

This case report presents the first available ultrasonographic description and images of intrapancreatic splenic tissue in a cat. It is thought to be a benign lesion of low clinical significance and therefore defining its imaging characteristics may allow for improvement in diagnostic suspicion without resorting to excisional surgery.