Etiology and pathogenesis of the prune belly syndrome

Abstract

The congenital triad of abdominal muscle deficiency, severe urinary tract abnormality, and cryptorchidism forms a rare but well-defined clinical condition popularly known as the prune syndrome (PBS) [1–10]. The term prune belly is descriptive of the characteristic wizened, dried-plum appearance in the newborn and young infant (Fig. 1). The peculiar and, in classical cases, pathognomonic aspect of the thin, transparent, redundant abdominal skin, which is loose rather than stretched, nestling to the wobbly intestines at birth, becomes less marked with advancing age. With age, the wrinkles flatten out as the subcutaneous fat and intraabdominal content increase, expanding further the flaring and floppy flanks and the paunch. In addition to the therapeutic challenge presented by the PBS, its etiology and pathogenesis have been controversial. Earlier studies suggested a mesenchymal developmental arrest during the 6th to 7th week of gestation leading to coordinated defects of dependent structures [11, 12]. Recently, an old hypothesis has been resurrected and extended [13–15]. It explains the morphologic characteristics of the PBS as sequelae of an intrauterine distension of the abdomen, usually by enlargement of the bladder due to an obstruction of the proximal urethra [16–19]. Operative removal of the obstructing tissue such as an valve would under these circumstances be a logical measure in the affected newborn or infant. Our personal experience with 14 patients with PBS and a critical analysis of the literature do not support the hypothesis of a secondary pathogenetic sequence arising from a primary obstructive uropathy. PBS and the urethral obstruction malformation complex [14] are different conditions, which can be separated by clinical, radiographic, endoscopic, and histologic evaluation. This distinction determines the choice of the most effective form of therapy.