Pathology of cloaca anomalies with case correlation.

During the fourth week of human embryo development, a transient common channel known as a cloaca is formed from which three cavities with three external orifices arises. Cloaca anomalies occur when there is failure of separation of the rectum, vagina, and urethra channel resulting in a single drain into the perineum. In our previous institutional studies, Runck et al. compared human and mouse cloaca development and found early mis-patterning of the embryonic cloaca deranged hedgehog and bone morphogenetic proteins (BMP) signaling. Also, our group reported the embryological correlation of the epithelial and stromal histology found in step sections of the common channel in 14 cloaca malformations in humans. In this review, we present the pathology of a 4-year-old female with a cloaca and VACTERL complex, and summarize our current knowledge of cloaca pathology. Furthermore, we suggest that careful pathological examination of cloaca specimens in conjunction with surgical orientation may result in a better understanding of the etiology of this condition.