Histological characteristics of eosinophilic myenteric ganglionitis: an under-recognised cause of chronic intestinal pseudo-obstruction.

Eosinophilic myenteric ganglionitis (EMG) is characterised by eosinophilic infiltration of the myenteric plexus. EMG has been rarely reported as a cause of chronic intestinal pseudo-obstruction (CIPO), and its histopathological features are not fully elucidated. We analysed seven patients with CIPO. Three of them were diagnosed with EMG and four patients were categorised as non-EMG. Clinicopathological features were similar in both groups. These features included subtle to mild lymphocytic infiltration at the myenteric ganglia/muscularis propria, loss of myenteric ganglions and interstitial cells of Cajal (ICC), and no significant findings in the mucosa. The exceptions were moderate to severe degree of eosinophilic infiltration at the myenteric ganglia/muscularis propria in EMG. Functional gastrointestinal obstruction may be associated with inflammatory cell infiltration at the myenteric ganglia/muscularis propria, leading to subsequent hypoganglionosis and deficiency of ICC in EMG. Pathologists and clinicians should be aware of this distinction during differential diagnosis of patients with CIPO.