Spontaneous unilateral renal dysplasia in a clinically healthy cynomolgus monkey (Macaca fascicularis)

Bilateral renal dysplasia with systemic fibrous osteodystrophy in a four-toed hedgehog (Atelerixalbiventris)

A 4-month-old female four-toed hedgehog (Atelerix albiventris) presented with lethargy, anorexia, dyspnoea and weight loss. Following death, post-mortem computed tomography (CT) and an autopsy were performed. CT revealed that the external surfaces of bones, including the cranial bones and vertebrae, were rough and osteolytic lesions were present multifocally in the ribs and some appendicular bones. On gross examination, both kidneys were severely enlarged and, on cut sections, a few cysts (up to 1 mm diameter) were present in the medulla. The cervical, thoracic and lumbar vertebrae were diffusely enlarged with deformation of the intervertebral discs. Histologically, there were immature glomeruli and tubules and adenomatoid/atypical epithelium in the kidneys. These changes were interpreted as renal dysplasia. In the bones evaluated, the trabeculae were thinner than normal, decreased in number and surrounded by many osteoclasts, with abundant fibrous connective tissue between atrophied trabeculae. These changes were consistent with fibrous osteodystrophy. Although kidney diseases are common in four-toed hedgehogs, there are no reports of congenital renal diseases, including renal dysplasia. To the best of our knowledge, this is the first report of the clinical and pathological features of renal dysplasia with fibrous osteodystrophy in a four-toed hedgehog.

Congenital Unilateral Renal Aplasia in a Cynomolgus Monkey (Macaca fascicularis) With Investigation Into Potential Pathogenesis

We describe and characterize unilateral renal aplasia in a cynomolgus monkey (Macaca fascicularis) from a chronic toxicology study adding to the limited histopathology reports of congenital renal anomalies in macaques. In the current case, the affected kidney was macroscopically small and characterized microscopically by a thin cortex with an underdeveloped medulla and an absent papilla. The remnant medulla lacked a corticomedullary junction and contained only a few irregular collecting duct-like structures. The cortex had extensive interstitial mature collagen deposition with fibromuscular collar formation around Bowman's capsules. Due to parenchymal collapse, mature glomeruli were condensed together with occasional atrophic and sclerotic glomeruli. The majority of the cortical tubules were poorly differentiated with only small islands of fully developed cortical tubules present. Histochemical and immunohistochemical stains were utilized to demonstrate key diagnostic features of this congenital defect, to assist with differentiating it from renal dysplasia, and to provide potential mechanistic pathways. Immunostaining (S100, paired box gene 2 [PAX2], aquaporins) of the medulla was compatible with incomplete maturation associated with aplasia, while the immunostaining profile for the cortex (vimentin, calbindin, PAX2-positive cortical tubules, and smooth muscle actin-positive fibromuscular collars) was most compatible with dedifferentiation secondary to degenerative changes.