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Bladder
Acquired non-neoplastic anomalies
Author: Nat Pernick, M.D. (see Authors page)
Editor: name, affiliation
Revised: 12 February 2010, last major update - February 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.
Definition
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● Tamm-Horsfall protein (THP) is a high molecular weight glycoprotein discovered by Tamm and Horsfall (J Exp Med 1952;95:71)
● Normally synthesized by thick ascending limb of loop of Henle, possibly distal convoluted tubules
● Most abundant protein in urine of healthy individuals
● May accumulate in renal parenchyma, perirenal soft tissue, renal hilar lymph nodes or bladder with pathologic conditions
Terminology
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● Also known as uromodulin, from UMOD gene on #16 (Wikipedia)
Pathophysiology
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● Inserted into luminal cell surface of renal tubules by glycosyl-phosphatidylinositol (GPI)-anchor, then excreted in urine at a rate of 50 - 100 mg/day
● Stones may form due to defective urinary Tamm Horsfall protein, due to lack of sialic acid (Int J Biol Sci 2008;4:215)
● Has a strong tendency to form macroaggregates of several million Daltons, particularly in highly tonic solutions
● Forms the matrix of urinary casts and stones
Epidemiology
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● THP deposits in 60% of cystectomy specimens, 4% of bladder biopsies
● In bladder specimens with THP deposits, mean age is 61 years, range 45-78 years, 85% are men (AJSP 1994;18:615)
Sites
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Etiology / clinical features
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● Deposited in areas of necrosis, inflammation, fibrinous exudates, ulcer, crystalline material
● May be host defense factor against Proteus mirabilis urinary tract infections (J Urol 2009;181:2332)
● May have role in pathophysiology of interstitial cystitis (BJU Int 2009;103:1085)
● Comprises matrix of urinary casts formed during acute kidney injury (Webpath tutorial) and matrix of urinary stones
● Also present in deposits associated with interstitial kidney disease
● Also associated with urothelial carcinoma, nephrogenic adenoma
Prognostic factors
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Case reports
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Treatment
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Clinical images
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Gross description (Macroscopy)
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● Large, waxy, pale or weakly eosinophilic mass
Gross images
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Micro description (Histopathology)
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● Glassy, PAS+ acellular material
● May also appear as strands of eosinophilic material obscured by fibrinous exudates or necrotic tissue
Micro images
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Diagram of Tamm-Horsfall protein secretion Urinary sediment showing red cell cast,
(green dots), forming a hyaline cast in the in which crenated red cells are embedded
collecting duct in a Tamm-Horsfall protein matrix
Associated with granulomatous pyelitis (H&E, PAS, IHC)
No thumbnails: Nephronophthisis: end-stage renal disease; lymphatics; pyelonephritis #1-protein cylinder; #2-protein cylinder; #3-immunostain
Cytology description
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Cytology images
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Positive stains
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● PAS, trichrome (pale blue)
● Anti Tamm-Horsfall protein antibody
Negative stains
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Electron microscopy descriptions
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● Nonbranching 4 nm wide parallel fibrils
Electron microscopy images
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No thumbnails: in lymphatics
Molecular / cytogenetics description
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Molecular / cytogenetics images
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Differential Diagnosis
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● (link to topic)
Additional references
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End of Bladder > Acquired non-neoplastic anomalies > Tamm-Horsfall protein
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