A tortuous proximal urethra in urorectal septum malformation sequence?

Area of Science:

• Medical Science
• Pediatric Pathology
• Developmental Biology

Background:

• Urorectal septum malformation sequence (URSMS) is a rare congenital anomaly.
• It involves incomplete separation of the cloaca, leading to significant malformations of the urinary, rectal, and genital systems.
• Severe cases are often associated with high mortality due to associated anomalies like lung hypoplasia.

Observation:

• A newborn male with URSMS presented with genital and rectal anomalies, expiring on day one due to severe lung hypoplasia.
• Autopsy revealed a blind-ending colon, enlarged bladder without a visible urethra, and dysplastic kidneys.
• Histological analysis of the bladder outlet showed a cone-shaped structure with undeveloped urethral lumina and ductal buds.

Findings:

• The undeveloped urethral structure exhibited transitional epithelium with squamous metaplasia.
• Branching ductal buds lined with columnar epithelium stained positive for prostatic acid phosphatase.
• Basal cells of these buds stained positive for p63 and high molecular weight cytokeratin, indicating normal early prostatic duct histology.

Implications:

• This study provides the first histological images of an undeveloped, obstructed urethra in the context of URSMS.
• The findings offer insights into the early developmental stages of the urethra and prostate in this rare condition.
• Understanding these histological features may aid in future diagnostic and therapeutic strategies for URSMS patients.