Chronic intestinal pseudoobstruction (CIPO) is classified into enteric visceral myopathies, neuropathies, and/or mesenchymopathies. Although the histology usually permits to highlight pathologic abnormalities of CIPO, it fails in almost a third of cases. The yield of a systematic immunohistochemistry needs to be evaluating.
Twenty-one adult patients with idiopathic CIPO [11 females/10 males, median age 23.1 (0.3 to 57) y] were included and compared with 27 control and 10 with mechanical obstruction patients. Comparison between standard histology (hematoxylin and eosin-stained sections) and systematic immunohistochemistry using muscular (smooth muscle alpha-actin, desmin, and smoothelin-A/B), nervous (Hu C/D, Bcl-2, and S100 protein), and mesenchymal (CD117) markers was carried out.
Histology showed neuromuscular abnormalities in 13 out of 21 (62%) patients, consisting of enteric visceral myopathy in 9 (43%) patients, enteric visceral neuropathy in 2 (9.5%), and mixed neuromyopathy in 2 (9.5%). Among the 8 patients who had no histologic structural abnormality, 6 patients (75%) had underlying abnormalities detected with immunohistochemistry: immunostain with Hu C/D detected a hypoganglionosis (<50 ganglion cells/cm) in 6 out of 21 (29%) patients, 4 of them undiagnosed on standard histology; CD117 (c-kit) detected a interstitial cells of Cajal defect in 10 out of 21 (48%) patients, 2 of them with no histologic structural abnormality. Smoothelin-A/B and desmin were useless as normally expressed in all patients with no myopathy; although it was not relevant in ileal samples (86% of abnormal expression in control patients), smooth muscle alpha-actin showed an abnormal expression in 2 CIPO patients (2/21).
Immunohistochemistry using Hu C/D and CD117 antibodies combined to the standard histology increased the yield of detection of neuromuscular abnormalities in idiopathic CIPO patients.