What causes Pseudo-kidney Sign in bowel on ultrasound?
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Answer:
Pseudo-kidney sign represents the sonographic appearance of intussusception, where invaginated bowel loops form a reniform mass with central hyperechoic fat and mucosa surrounded by a hypoechoic muscular rim; it is also seen in gastrointestinal wall thickening from malignancies like gastric or colonic adenocarcinoma, lymphoma, Crohn disease, diverticulitis, and intestinal tuberculosis.
Why is it called so?
It is named for its reniform (kidney-like) shape on ultrasound, with a central hyperechoic region resembling renal parenchyma and sinus surrounded by a hypoechoic cortex-like rim. It was first described in colonic carcinoma.
Pathophysiology
Intussusception causes telescoping of proximal bowel into distal bowel, trapping hyperechoic mesenteric fat and lumen centrally while the invaginated hypoechoic bowel wall forms the outer rim; in neoplasms, asymmetric wall thickening mimics this layered reniform pattern.
Alternative names: Rosette sign
Other associated named signs: Target sign, doughnut sign, crescent-in-doughnut sign
References
Access all radiology signs posted so far: https://radiogyan.com/radiology-signs/
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