Testis & paratestis

Other tumors


Editor-in-Chief: Debra L. Zynger, M.D.
Gang Wang, M.D., Ph.D.

Last author update: 28 January 2020
Last staff update: 3 August 2023

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PubMed Search: Metastases testes

Gang Wang, M.D., Ph.D.
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Cite this page: Wang G. Metastases. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testismetastases.html. Accessed September 29th, 2023.
Definition / general
  • Tumors secondarily involving testis and paratesticular structures from distant sites
  • Excludes hematopoietic tumors
Essential features
  • Most have known history of primary but rarely the initial presentation
  • Histologic features recapitulate their site of origin
  • Should be differentiated from germ cell tumor, sex cord stromal tumor, malignant mesothelioma and adenocarcinoma of the rete testis or epididymis
  • Also called secondary tumors of the testis
Clinical features
  • Most nonsymptomatic or incidental finding
  • Most unilateral and solitary
  • Rarely present as carcinoma of unknown primary
  • Clinical information and ancillary investigations can be more helpful than special histological techniques in the differential diagnosis
Radiology images

Images hosted on other servers:

Renal cell carcinoma metastasis to testis

Lung adenocarcinoma metastasis to testis

Colorectal adenocarcinoma metastasis to testis

Case reports
Gross description
  • Localized mass, multiple nodules
Gross images

Contributed by Debra L. Zynger, M.D.
Metastatic prostatic adenocarcinoma

Metastatic prostatic adenocarcinoma

Images hosted on other servers:

Metastatic colorectal adenocarcinoma

Metastatic renal cell carcinoma

Microscopic (histologic) description
  • Histologic features recapitulate their site of origin
  • Metastatic prostatic adenocarcinoma tends to involve the tubular system
  • Other metastatic carcinomas tend to infiltrate the testicular interstitium while sparing the seminiferous tubules
  • Prominent lymphovascular invasion
Microscopic (histologic) images

Contributed by Gang Wang, M.D., Ph.D.

Metastatic prostatic adenocarcinoma
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Involvement of the tubular system

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Cribriform pattern
most frequent,

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Solid growth pattern

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Metastatic ductal adenocarcinoma

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Positive for PSA

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Positive for ERG

Metastatic renal cell carcinoma, clear cell type
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Broad pushing borders

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Mixed patterns

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Positive for PAX8

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Positive for CAIX

Metastatic colorectal

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Cystic spaces containing mucin

Metastatic cutaneous squamous
cell carcinoma

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Infiltrating and anastomosing nests

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Positive for p40

Positive stains
  • Mucin (teratomatous elements and yolk sac tumors may also be positive)
  • EMA
Negative stains
Molecular / cytogenetics description
  • Detection of isochromosome 12 by fluorescence in situ hybridization would suggest a primary germ cell tumor rather than a metastases
Sample pathology report
  • Right testis and spermatic cord, radical orchiectomy:
    • Metastatic renal cell carcinoma, clear cell type, 2 cm, confined to the testicular parenchyma
    • Margins of resection, negative for malignancy
Differential diagnosis
Board review style question #1

Which of the following is the most common primary site of metastatic carcinoma in the testis?

  1. Bladder
  2. Kidney
  3. Prostate
  4. Lung
  5. Colon
Board review style answer #1
C. The most common primary site of metastatic carcinoma in the testis is the prostate

Comment Here

Reference: Metastases to testes
Board review style question #2

    As shown in the figure, there is an adenocarcinoma in the testis. Which of the following markers is the best for differentiation between this metastatic adenocarcinoma in the testis and primary adenocarcinoma of the rete testis or epididymis?

  1. Calretinin
  2. CDX2
  3. CK7
  4. CK20
  5. PAX8
Board review style answer #2
E. Primary adenocarcinomas of the rete testis or epididymis are positive for PAX8 while metastatic adenocarcinomas from other sites are usually negative for PAX8 (except kidney and thyroid)

Comment Here

Reference: Metastases to testes
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