Congenital prepubic sinus: A variant of dorsal urethral duplication suggested by immunohistochemical analysis

Purpose: Congenital prepubic sinus is a rare disorder of uncertain etiology . Immunohistochemical staining is used to elucidate the etiology of the sin us. Materials and Methods: We treated 5 patients with congenital prepubic sinus . A sinogram, delineated the tract, which was then excised. In addition to routine hematoxylin and eosin stain of the 5 specimens, immunohistochemical analysis was also performed with smooth muscle and sarcomeric actin, high (34 beta E12) and low molecular weight cytokeratin (35 beta H11), and cytok eratin 7 antibodies. Results: The 2 females and 3 males were 1 month to 14 years old. All patien ts had presented with purulent discharge from the sinus opening. Hematoxyli n and eosin stain demonstrated transitional and squamous epithelium lining the sinus. Immunohistochemical study showed that the stain with 3 cytokerat in antibodies was moderately to strongly positive in all patients at the pr oximal end, low molecular weight cytokeratin weakly to moderately positive and cytokeratin 7 weakly positive to negative in 4 at the distal end. The r esults suggested that the lining epithelium was transitional proximally and squamous distally. An exception was a female patient who had the shortest tract lined with squamous epithelium only. Furthermore, smooth muscle but n ot sarcomeric actin demonstrated smooth muscle bundles around the sinus tra ct in 4 patients. Conclusions: The existence of transitional epithelium in the proximal part of the sinus and presence of smooth muscle bundles around it reinforce the theory that congenital prepubic sinus is a variant form of dorsal urethral duplication.