Detrusor mast cells in refractory idiopathic instability.

The diagnosis of interstitial cystitis (IC) is not usually considered in patients with idiopathic instability. Because histamine provokes detrusor contractions in vitro, we assessed detrusor mast cell counts in 29 females with refractory instability. Raised mast cell counts (greater than 28/mm2 of detrusor muscle, consistent with a histological diagnosis of IC) were found in 29% of such cases. Thus cystoscopy and bladder biopsy should be considered in patients with idiopathic instability which fails to respond to anticholinergic drugs, as alternative therapy may be useful. Patients with refractory instability and normal detrusor mast cell counts often gave a history of prolonged childhood nocturnal enuresis (55% of cases); in contrast, patients with intractable instability and abnormally high mast cell counts seldom gave such a history (12%). These trends may give some insight into the aetiology of idiopathic instability--"congenital" or acquired?