Histopathological characteristics of ketamine-associated uropathy and their clinical association

To investigate the histopathological findings in ketamine-associated uropathy (KU) and their clinical association.

Thirty-eight KU patients had received history investigation and video urodynamic study. Twelve of them were clinically mild KU who were admitted for cystoscopic hydrodistention. The other 26 patients were severe KU who were admitted for enterocystoplasty with or without ureter reimplantation. Bladder and ureter specimens were harvested during operation, and a single pathologist reviewed all specimens under hematoxylin and eosin stain. The severity of histopathological findings was graded with a 4-point scale (0: none, 1: mild, 2: moderate, and 3: severe) RESULTS: Inflammatory cells infiltrations and nerve hyperplasia were found in the mucosa, muscle, and subserosal layers of KU bladders and ureter. In the mild KU bladder mucosa, the predominant component of the infiltrating inflammatory cells was lymphocytes. In contrast, neutrophils, eosinophils, lymphocytes, and plasma cells infiltration were noted in the mucosa of almost all severe KU bladders. Clinical severe KU was significantly correlated with severe to moderate lymphocytes, plasma cells, neutrophils, eosinophils infiltration, and nerve hyperplasia in bladder mucosa. KU patients with moderate or severe neutrophils or lymphocytes infiltration in bladder mucosa had significantly more severe bladder pain and smaller bladder capacity.

The histological findings of KU showed whole-layer inflammation and nerve hyperplasia in bladder mucosa. The severity of inflammatory cell infiltration in the bladder mucosa is associated with clinical symptoms. A histopathological examination might be a useful tool to discriminate the KU severity in patients.