Grading
The 2014 ISUP coonsensus proposal is to group Gleason patterns as defined below iinto clinically important groups
Group 1
Gleason score ≤6 (3+3 and below)
Group 2
Group 3
Group 4
Gleason score 8 (4+4, 3+5 or 5+3)
Group 5
We report both Group and Gleason Score
The Gleason grading system is intended to be applied primarily at low power
Don’t go down on high power looking for one or two fused glands
Should be visible at 100x (10x objective)
The Score is the sum of the two most prevalent patterns subject to the following:
For needle biopsies
The predominant pattern is given first
The second most predominant pattern is given second, e.g. Gleason score 3+4 as long as the second score applies to >5% of the carcinoma
If the tertiary pattern is higher than both of the first two, it becomes the second pattern, regardless of its prevalence, e.g. 3+4 with tertiary 5 becomes 3+5
For prostatectomies
As for needle biopsies except that a high tertiary pattern is reported simply as a tertiary pattern e.g. Gleason score 3+4 with tertiary 5
Gleason grading criteria (based on 2005 ISUP modified system) (Epstein 2005, Egevad 2012)
Pattern 1
Circumscribed nodule of closely packed uniform glands
Described only in transition zone
Most if not all cases of Gleason 1+1 are really adenosis
We do not make this diagnosis, even as a secondary pattern
Pattern 2
Circumscribed nodule of loosely packed slightly variable glands
Described only in transition zone
Many/most cases of Gleason 2+2 are really adenosis
The entire lesion must be examined
IPOX for basal cells must be completely negative
We do not make the diagnosis of 2+2 or 2+3 on needle biopsies
Transition zone is rarely sampled and the entire lesion is rarely encompassed by the core
If the lesion is considered to be carcinoma it should be graded at least 3+3
Pattern 3
Single glands of variable size and density, with an infiltrative pattern, each separated by at least a strand of stroma
Critical distinctions from higher grade carcinomas are the widespread presence of well formed lumens and the lack of fused glands
This is the common pattern of low grade carcinoma
If no higher grade pattern is present, diagnose as Gleason 3+3
Resist the urge to imagine a component of pattern 2, even if the focus is small
Classical Gleason grading included sharply circumscribed cribriform in pattern 3
We consider this pattern 4, or in some cases high grade PIN
Pattern 4
Ragged infiltration with poorly formed glands or sheets and cords of fused glands
Poorly formed glands includes small nests of cells with only a rudimentary formed lumenal space (almost rosette like)
Intracytoplasmic lumens do not count as pattern 3, they are 4 or 5
Fused glands are recognized as back to back glands without intervening stroma
May produce a cribriform pattern
Glomeruloid bodies are pattern 4 by definition
Clear cell hypernephroid is pattern 4 by definition
Pattern 5
Ragged infiltrative single cells, cords or sheets without gland formation, small solid cylinders or any pattern with comedonecrosis
Occasional cells with these features can be seen in pattern 4, especially peripherally
Comedonecrosis should be unequivocal
Signet ring carcinoma is by definition pattern 5
Special considerations for grading
The proper score for a very small focus that is just barely diagnostic of carcinoma is 3+3=6, not 2+2 or 3+2
Even very small foci should get two patterns to avoid confusion (single number in a report may appear to be a sum of two patterns)
The most critical clinical distinctions occur with the recognition of pattern 4
Some urologists want to know what percentage of the cancer is pattern 4, if yours do, then report it
A recent large study suggests that carcinomas of Gleason 3+3 or lower do not have the ability to metastasize to nodes (Ross 2012)
Scores should be given for each individual core, if they are received separately labeled
Mucinous carcinoma should be graded bassed on the underoying pattern (usully it isi 4)
Treated carcinoma cannot be graded
If treated with radiation, we typically report that it cannot be graded but that it shows features of Gleason pattern 3 or 4 etc. if possible
Hormonally treated carcinoma cannot be graded at all
The rare variant of p63 positive adenocarcinoma should not be graded (Giannico)
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