Prostate gland & seminal vesicles

Acinar / ductal adenocarcinoma

Vanishing cancer



Topic Completed: 21 July 2021

Minor changes: 21 July 2021

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PubMed Search: Vanishing prostate cancer

Kenneth A. Iczkowski, M.D.
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Cite this page: Iczkowski KA. Vanishing cancer. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/prostatevanishing.html. Accessed December 3rd, 2021.
Definition / general
  • First described in 1995, vanishing cancer indicates no residual tumor found in radical prostatectomy specimen despite confirmed tumor in needle biopsy (Am J Surg Pathol 1995;19:1002)
  • Sometimes, only high grade prostatic intraepithelial neoplasia (HGPIN) or atypical small acinar proliferation suspicious for but not diagnostic of cancer (ASAP) is found
Essential features
  • Contemporary incidence of vanishing cancer is 0.2% of radical prostatectomy specimens; it was higher a decade or two ago when prostatectomy was being performed for smaller / lower grade cancers
  • Incidence is higher in large prostates or in preoperatively treated ones
  • Resolution of dilemma involves complete tissue submission, cancer specific immunostains, use of second opinion, consider flipping blocks to other surface; some residual cancers simply cannot be detected after the above efforts
ICD coding
  • ICD-10: C61 - malignant neoplasm of prostate
Epidemiology
Etiology
  • Most often, the phenomenon is attributed to the fact that routine histologic sections cannot evaluate every cubic millimeter of prostate volume, so small cancer foci remain in the paraffin block
  • Rarely, prostate cancer may have been ablated by the biopsy or transurethral resection procedure (BJU Int 2004;94:939)
  • Currently, more patients are receiving preoperative androgen deprivation, such as enzalutamide, that shrinks the cancer (Urology 2005;65:76, Clin Cancer Res 2017;23:2169)
  • It is also proposed that a minute cancer focus at the edge of the prostate may be inadvertently left behind in the overzealous attempt to perform a nerve sparing procedure (Indian J Cancer 2013;50:170)
Diagnosis
  • Diagnostic resolution should include these steps in the following order (Urol Oncol 2019;37:696):
    • If the prostatectomy tissue has been partially submitted, complete submission should be pursued
    • Get a second pathologist, particularly a urologic pathologist, to reread the resection slides
    • Review the biopsy that was diagnostic of cancer, if slides are available
    • Immunostains (see below)
    • Flip tissue in some or all of the paraffin blocks and have the opposite surfaces of the tissues cut
    • DNA identity analysis can be performed if specimen switching is suspected (see below)
Laboratory
Gross description
Gross images

Images hosted on other servers:
Missing Image

Paraffin blocks
before and
after block
flipping

Positive stains
  • P504S racemase is positive in cancer; get immunostains on deeper levels, on areas initially suspicious for cancer (ASAP)
Negative stains
Molecular / cytogenetics description
  • Microsatellite analysis can be performed on the prostatectomy and biopsy specimens to confirm specimen identity; this very rarely shows a specimen switch (1 in 10 cases of vanishing cancer was attributed to specimen mixup) (Am J Surg Pathol 2005;29:467)
  • This is particularly indicated if there is high grade or high volume cancer on the biopsy (Am J Surg Pathol 2005;29:467)
Sample pathology report
  • Prostate, radical prostatectomy:
    • No residual cancer (see comment)
    • Comment: This diagnosis is reached after complete submission and microscopy of all prostatic tissue. The tissue in the blocks was also reembedded and the reverse sides were cut into microscopic slides. The prostatic basal cell / P504S immunostain was performed to interrogate block X and it was confirmatory. The original diagnosis of cancer was confirmed by rereviewing the biopsy specimen. Dr. X agrees with this interpretation.
Differential diagnosis
  • Biopsy specimen switch:
    • Specimen mixup with another patient must be excluded if the biopsy showed high grade or high volume cancer and no cancer is seen in the resection
    • Molecular analysis can be performed (Am J Surg Pathol 2005;29:467)
  • Biopsy false positive:
    • Correct diagnosis of cancer on the prior biopsy should be confirmed
    • Immunostains (AMACR+ / p63, HMWK-) can be used if not previously performed
Board review style question #1
A 70 year old man undergoes radical prostatectomy with an organ weight of 90 g. What is the least likely contributor to finding no residual cancer?

  1. Partial sampling of every other tissue slice (as is commonly done for > 50 g prostates)
  2. Preoperative course of enzalutamide ablated any residual cancer
  3. Prior prostate biopsy specimen switch
  4. Residual cancer remains in the paraffin, even after flipping the blocks
Board review style answer #1
C. A specimen switch of the prior prostate biopsy is the least likely explanation and could be detected molecularly. If initial partial sampling was done, complete sampling of the tissue should be pursued; if cancer is not found, flipping the blocks is recommended; use of immunostains may help if any foci are suspicious. Finally, it is possible that a preoperative course of enzalutamide has ablated any residual cancer.

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