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Renal ectopia pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

Overview

The exact pathogenesis of [disease name] is not fully understood.

OR

It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].

OR

[Pathogen name] is usually transmitted via the [transmission route] route to the human host.

OR

Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.

OR


[Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].

OR

The progression to [disease name] usually involves the [molecular pathway].

OR

The pathophysiology of [disease/malignancy] depends on the histological subtype.

Pathophysiology

Pathophysiology

  • Normal ascent of the kidneys is required for formation of the extraperitoneal perirenal fascial planes.
  • Ectopia (or renal agenesis) results in failure of development of fascial layers in the flanks on the side not occupied by renal tissue.
  • Lack of restraining fascia leads to possible malposition of bowel into the extraperitoneal fat of the empty renal fossa and relaxation of mesenteric supports for bowel loops in this region.

Physiology

The normal physiology of [name of process] can be understood as follows:

Crossed-fused renal ectopia

  • Crossed ectopy = kidney located on the opposite side of the midline from its ureter. [1] [2] [3] [4]
  • In 90% of crossed ectopy, there is at least partial fusion of the kidneys (the remainder demonstrate two discrete kidneys on the same side, crossed-unfused ectopy)
  • Due to improper renal ascent in embryogenesis (4th-8th week of fetal life – normally, the kidney reaches its appropriate position at L2 level at the end of the 2nd month)
  • Fusion of the kidneys within the pelvis leads to crossed-fused renal ectopia.
  • Abnormally situated umbilical artery prevents normal cephalic migration. Another theory is that the ureteric bud crosses to the opposite side and induces nephron formation in the contralateral metanephric blastema.

Pathogenesis

  • Renal ectopia results as a consequence of abnormal renal ascent in embryogenesis with fusion of the kidneys within the pelvis.
  • It is thought to occur in the first trimester, at around 4th-8th week of fetal life (In a normal situation the kidney reaches its appropriate position at L2 level at the end of the 2nd month).
  • Some evidence supports that an abnormally situated umbilical artery prevents normal cephalic migration.
  • Another theory is that the ureteric bud crosses to the opposite side and induces nephron formation in the contralateral metanephric blastema. The result is a single renal mass with two collecting systems being located on one side of the abdomen.
  • Normal ascent of the kidneys is required for formation of the extraperitoneal peri-renal fascial planes and therefore ectopia results in failure of development of fascial layers in the flanks on the side not occupied by renal tissue. The lack of restraining fascia leads to possible malposition of bowel into the extra-peritoneal fat of the empty renal fossa and relaxation of mesenteric supports for bowel loops in this region.
Genetics

Genetics

[Disease name] is transmitted in [mode of genetic transmission] pattern.

OR

Genes involved in the pathogenesis of [disease name] include:

  • [Gene1]
  • [Gene2]
  • [Gene3]

OR

The development of [disease name] is the result of multiple genetic mutations such as:

  • [Mutation 1]
  • [Mutation 2]
  • [Mutation 3]
Associated Conditions

Associated Conditions

Gross Pathology

Gross Pathology

On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].

Microscopic Pathology

Microscopic Pathology

On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].

References

References

  1. Dunnick, N.R., Sandler, C.M., Newhouse, J.H., and Amis, E.S. Textbook of uroradiology, 3rd Edition. Lippincott Williams and Wilkins, 2001.
  2. Dyer, R.B., Chen, M.Y., and Zagoria, R.J. Classic signs in uroradiology. Radiographics, 2004; 24:S247-S280.
  3. Gay, S.B., Armistead, J.P. Weber, M.E., and Williamson, B.R.J. Left infrarenal region: anatomic variants, pathologic conditions, and diagnostic pitfalls. Radiographics 1991; 11: 549-570.
  4. Meyers, M.A., Whalen, J.P., Evans, J.A. and Viamonte, M. Malposition and displacement of the bowel in renal agenesis and ectopia: new observations. AJR, 1972; 117,2: 323-333.

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