Prostatic Adenocarcinoma
Supplemental Studies
Immunohistology
- Immunohistochemistry is primarily used in prostate pathology in three situations:
- Identification of a differentiated, gland forming metastasis as prostatic in origin
- Prostate specific antigen (PSA) and prostatic acid phosphatase (PAP) are very sensitive and specific in this context
- Virtually all untreated gland forming prostatic adenocarcinomas are positive for PSA and PAP
- Either one is generally sufficient
- Hormone treatment may lead to a negative result
- Reactivity with other carcinomas is quite limited
- PSA and PAP can stain salivary gland and breast neoplasms
- PSA can stain cystitis glandularis and bladder adenocarcinoma
- PAP stains rectal carcinoids
- PSA is negative
- Synaptophysin and chromogranin frequently stain rare to scattered cells in prostate carcinoma
- Backup equivocal cases with NKX3.1
- The choice of the complementary marker depends upon the context
- TTF1 (lung) may stain small cell carcinoma of the prostate but is otherwise negative
- CDX2 (GI tract) may react with a subset of prostate adenocarcinoma
- Usually focal and weak but may be strong (including non-mucinous carcinomas)
- GATA3 is sensitive (90%) and specific (also reacts with TCC)
- BRST2 (GCDFP15) stains 60% of breast carcinoma and may stain nearly half of prostate adenocarcinomas
- CK7 and 20 are of use only if they can exclude a carcinoma of another site
- For example, a CK7 negative result is strongly against lung adenocarcinoma
- Staining of prostate carcinomas is not very helpful as they may express a variety of CK phenotypes, most often CK7-20-
- Racemase/AMACR is not useful in this situation
- It is present in carcinomas of many types and sites
- Distinction of very high grade prostatic adenocarcinoma from high grade urothelial carcinoma
- NKX3.1 (nuclear) is most sensitive for prostate and quite specific
- PSA and PAP may miss some (20%?) of very high grade or treated carcinomas
- All three may be needed
- Other backup p53 (cytoplasmic),
- GATA3, p63 and/or high molecular weight cytokeratins are useful complementary markers
- Nearly 90% of TCC are positive
- Only extremely rare prostate adenocarcinomas are reactive
- Distinction of benign from malignant prostate
- p63 and high molecular weight cytokeratins (34BE12, CK5/6) are effective markers for basal cells
- The presence of even one basal cell in a population may be sufficient to rule out carcinoma
- The complete absence of basal cells is difficult to prove, but if the sample is large enough, it can be confirmatory of carcinomas
- Note - a subset of atrophic carcinomas express p63 in the malignant cells (Giannico)
- HMW keratin is negative
- Recoginzed by infiltrative pattern, poorly formed glands, stratified, often spindled nuclei
- Appear to do well clinically and should not be Gleason graded
- Racemase/AMACR is a useful marker for carcinoma in the prostate
- It is expressed in most carcinomas and is absent in most benign acini and ducts
- It is not specific enough for use as a sole marker
- Adenosis and partial atrophy may be positive
- Partial staining and weak to moderate staining may be seen in other benign lesions
- It is useful in cocktails that include basal cell markers
- The racemase can highlight populations of acini for close examination for the presence of basal cells
- Remember that it is not a marker of prostate origin in metastatic disease
- See atypical small acinar proliferation for further discussion of the approach to small foci
Genetic Study
- None currrently in use for diagnostic or therapeutic purposes
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