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Prostate

Microscopic mimics of prostatic carcinoma

Nephrogenic metaplasia / adenoma


Reviewers: Komal Arora, M.D., (see Reviewers page)
Revised: 22 May 2014, last major update June 2012
Copyright: (c) 2003-2014, PathologyOutlines.com, Inc.

General
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● Also known as adenomatoid metaplasia
● Metaplastic response of urothelium to injury
● Also associated with renal transplantation and intravesical bCG for bladder urothelial carcinoma
● Most common site is bladder; rarely affects prostatic urethra
● Extension of small tubules into fibromuscular stroma may simulate adenocarcinoma
● Usually does not recur

Pathogenesis
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● Increased shedding of renal tubular cells, together with injured urothelium or damaged host defenses, leads to adherence of renal tubular cells and the initiation of processes that result in nephrogenic adenomas (N Engl J Med 2002;347:684, N Engl J Med 2002;347:653)

Case reports
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● 72 year old man with TURP for obstruction (Case of the Week #209)

Micro description
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● Tubules (96%), inflammation (95%), extension into muscle (77%), structures resembling vessels (73%), peritubular sheaths (65%), prominent nucleoli (54%), cords and individual cells (46%), thyroidization (38%), blue-tinged mucinous secretions (32%), papillary configurations (19%), signet ring cell-like tubules (12%), no mitotic figures
● Adjacent urothelium (69%) with cuboidal metaplasia (61%) or squamous metaplasia (28%)
● Tubules composed of single layer of cuboidal or flattened cells with clear to eosinophilic cytoplasm, round nuclei with fine chromatin

Micro description
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Various images

Case of the Week #209:


       

       
72 year old man with obstructive symptoms

       
Left to right: PIN-4 (AMACR+, p63-, CK903-), CK7+, PSA-

Positive stains
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● CK7 (100%), focal PSA (36%), focal PSAP (50%), 34betaE12 (diffusely positive-11%, focally positive-44%, negative-44%), S100A1 (Am J Surg Pathol 2009;33:1031), AMACR (Am J Surg Pathol 2004;28:701), PAX2 (Mod Pathol 2006;19:356), PAX8

Differential diagnosis
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Prostatic adenocarcinoma: not associated with GU trauma, no adjuacent urothelium present, infiltrative, more atypia and pleomorphism, no thyroidization, usually no inflammation, CK7-, S100A1- (Am J Surg Pathol 2001;25:802)
Clear cell adenocarcinoma of the bladder: occasional clear cells, more prominent pleomorphism, especially hyperchromatic enlarged nuclei, and extensive muscular invasion (Hum Pathol 2010;41:594)

Additional References
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Am J Clin Pathol 1981;75:185, Hum Pathol 1994;25:390, Mod Pathol 1992;5:617, Arch Pathol Lab Med 2006;130:805


Fibromyxoid nephrogenic adenoma

Micro description
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● Admixture of classic tubular form of nephrogenic adenoma and compressed spindled cells within a fibromyxoid background
● Background matrix stains for mucin with periodic acid-Schiff and mucicarmine (Am J Surg Pathol 2007;31:1231)

End of Prostate > Microscopic mimics of prostatic carcinoma > Nephrogenic metaplasia / adenoma


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