Hyalinising pancreatic adenocarcinoma in a dog

By Tim Cushing

This is an elderly dog that presented for on and off vomiting and abdominal pain. An ultrasound scan revealed a cystic lesion in the pancreas. Cytology of the cyst showed evidence of non-specific haemorrhage and equivocal inflammation. A biopsy of the pancreas was also taken and submitted for histopathology.

Figure 1. Low magnification view of the pancreas revealing lobules of abnormal exocrine pancreatic tissue that are separated by an acellular pale eosinophilic matrix. The matrix is indicated by the two arrows (H&E, Bar = 250µm). A Congo red stain was performed to screen for amyloid and this was negative.
Figure 2. High magnification view of the exocrine pancreatic tissue and intervening matrix. There is mild to moderate dysplasia (anisokaryosis and multiple nucleoli) in the exocrine pancreatic epithelial cells (H&E. Bar = 50µm).

Final Diagnosis

Hyalinising pancreatic adenocarcinoma

Discussion:

The clinical impression at the time of biopsy was that of pancreatitis. Histopathologic examination did not reveal normal pancreatic tissue and based on the features above, a diagnosis of hyalinising pancreatic adenocarcinoma was made.

Pancreatic adenocarcinomas, in general, are high grade locally aggressive neoplasms with a rapid clinical course and frequent metastasis. Most will have metastasised by the time they become clinically evident. While the number of reported cases of this hyalinising variant of pancreatic adenocarcinoma are low, relative to non-hyalinising variants, these tend to have a less aggressive clinical course with prolonged time to metastasis and prolonged overall survival times. Dennis, et al. speculate that this more benign behaviour may be secondary either to the hyaline matrix material mechanically or biochemically impeding malignancy, or to the degree of tumour differentiation (or both).

Dennis MM, OBrien TD, Wayne T, Kuipel M, Powers BE. Hyalinizing pancreatic adenocarcinoma in 6 dogs. Vet Pathol. 2008;45:475-483
Charles, J. Pancreas In: Jubb, Kennedy and Palmer: Pathology of domestic animals (Vol 2).5th ed. Saunders Ltd. 2007 p 408