China
Africa
Explore chapters and articles related to this topic
The kidneys
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Histologically these tumours are characterized by three elements (i.e. they are triphasic): blastema, stroma, and immature tubules resembling the tissues found within the nephrogenic zone of fetal kidney (Figure 14.25). It is known that Wilms’ tumour arises from oncogenic events within the metanephric blastema of the fetal kidney and the tumour cells retain the capacity for partial differentiation into both the stromal and the epithelial elements, similar to the differentiation capacity of the normal metanephric blastema. The relative amounts of these different elements within the tumour vary. In about 5% of Wilms’ tumours extreme pleomorphism may be noted and this is termed ‘anaplasia’, which is a poor prognostic feature. Nowadays, >85% of children with Wilms’ tumour are cured by the combination of surgical and non-surgical management. This compares favourably with the position 30 years ago when the cure rate was between 10% and 30%.
SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
The definitive metanephroi are induced early in the fifth week by the ureteric buds that sprout from the mesonephric ducts. The ureteric bud induces the mesenchymal cells to condense around it, forming the metanephric blastema. The development of the ureteric bud and the metanephric blastema depends on reciprocal induction, neither being able to develop in the absence of the other. The metanephric blastema causes the ureteric bud to grow and bifurcate and the ureteric bud induces the mesenchyme to differentiate into nephrons. If the ureteric bud does not reach/signal properly to the surrounding mesenchyme, or vice versa, a kidney will not form (renal agenesis). If the ureteric bud bifurcates prematurely, a bifid ureter may result. Alternatively, if two ureteric buds develop an ectopic ureter may result.
Kidneys and ureters
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
The urinary tract is formed from the cloaca and intermediate mesoderm in parallel with the early differentiation of the metanephric blastema which will ultimately form the kidney. In the 6-week-old embryo, the mesonephric (Wolffian) duct and the paramesonephric (Mullerian) ducts run in parallel. By week 7, in the male, the Mullerian duct starts to regress, and the Wolffian duct will eventually develop into the epididymis and the caudal part of the vas deferens. In the female, the Mullerian ducts fuse to form the uterovaginal cord which will develop into the vagina. As the urogenital tract develops, there is simultaneous development of the fetal kidney. The ureteric bud arises from the distal end of the Wolffian duct as an unbranched diverticulum and invades the adjacent metanephric mesenchyme, initiating the branching collecting system within the primitive kidney. If the ureteric bud fails to develop, the kidney will not form. Renal development is controlled by the function of a number of transcription factors including PAX-2 and WT1.
Confirmation of Xp22.11 Duplication as a Germline Susceptibility Alteration in a Wilms Tumor Arising in Horseshoe Kidney
Published in Fetal and Pediatric Pathology, 2022
Hui-fang Zhou, Ina E. Amarillo, Stacy Snyder, Jorge L. Granadillo, Christopher J. O’Conor, Patrick Dillon, David Wilson, Frederick S. Huang, Louis P. Dehner, Mai He
Horseshoe kidney, or ren arcuatus, is a relatively common congenital renal anomaly defined by the fusion of the kidney lower poles, with a reported prevalence of 1 in 500 in the normal population with a male to female ratio of 2:1. The frequency is higher in those who present to urology clinics (1 in 304) and in certain chromosomal disorders, including Edward syndrome (∼67%), Turner syndrome (14-20%), and Down syndrome (∼1%) [15]. Horseshoe kidney results from an abnormal fusion of the metanephric blastema during the sixth to seventh week of gestation. This event disrupts the normal ascent of the kidneys, leading to an increased risk for renal obstruction, infection, and lithiasis. Horseshoe kidney is also associated with an increased risk for a variety of renal neoplasms including carcinoid tumor (62 − 82 fold), transitional cell tumor (3 − 4 fold), and Wilms tumor (2 fold) [15]. According to the report from the national Wilms tumor study group (NWTSG), in which all Wilms tumor cases registered from 1969-1998 were reviewed, the frequency of Wilms tumor arising in horseshoe kidney is 0.48%. It is still unclear what mechanisms govern the predisposition of horseshoe kidney patients to Wilms tumor [15].