Application of Gleason Grading Protocol in Specific Circumstances

 特殊情况下的Gleason Grading

Cumulative experience with the diagnosis of prostate adenocarcinoma during the 1990s and the current decade allowed recognition of multiple circumstances requiring guidelines for the appropriate application of the Gleason grading system. These circumstances included (1) recognition of histologic variants of prostatic adenocarcinoma, (2) the presence of focal (less than 5%) secondary patterns in tumors detected in needle biopsies, and (3) tumors containing tertiary, patterns. The current guidelines are the result of consensus of the ISUP Conference in 2005, and regarded as appropriate until more data dictate a different application of the grading protocol.

Histologic Variants and Treated Prostatic Adenocarcinoma.

Among the histologic variants of prostate adenocarcinoma, the current view is to disregard the features unique to foamy gland carcinoma, adenocarcinoma with either focal mucin production, or mucinous fibroplasia (collagenous micronodules), and assign a Gleason grade based only on the histologic pattern. By consensus, pseudohyperplastic pattern is regarded as pattern 3, and both ductal adenocarcinoma and colloid adenocarcinoma are regarded as examples of pattern 4. In contrast, no current consensus is available for Gleason pattern assignment for the diagnostic lesion, glomeruloid bodies. Finally, and importantly, a Gleason grade assignment is not to be rendered to (1) small cell (neuroendocrine) carcinoma, urothelial, and squamous cell carcinoma of the prostate; (2) prostate carcinoma in metastatic sites; and (3) prostate carcinoma following hormonal or radiation therapy.

Secondary Patterns with Focal (Less Than 5%) Representation in Needle Biopsies and Prostatectomy Specimens.

Examples of needle biopsies with the secondary Gleason pattern represented by focal (less than 5%) of the tumor are a diagnostic dilemma not clarified in the original Gleason protocol. Currently, by consensus, the suggested practice is to ignore the secondary pattern if the Gleason pattern is lower than the primary pattern. If the secondary Gleason is higher than the primary Gleason pattern, include this pattern regardless of its percentage contribution. There is no consensus among urologic pathologists on the reporting of the focal presence of a secondary pattern in prostatectomy specimens.

Tertiary Patterns in Needle Biopsies and Prostatectomy Specimens.

Uncommonly a tertiary Gleason pattern is encountered in needle biopsies. By consensus, when the spectrum of patterns is 3, 4, and 5, the final diagnosis should reflect the primary pattern and the highest pattern. When encountering Gleason patterns 2, 3, and 4, the final diagnosis should ignore the lowest pattern in the final diagnosis. When the same circumstance is encountered in prostatectomy specimens, the diagnosis should reflect the primary and secondary patterns and an accompanying note should quantitate the tertiary pattern.

Assignment of Gleason Score When Encountering Multiple Foci in Needle Biopsies and in Prostatectomy Specimens

The reporting of diagnostic needle biopsies is dependent on the manner of specimen submission. If multiple positive cores are submitted in a single specimen jar, the reported Gleason score is the combined primary and second patterns of all cores combined. If the positive cores are submitted in separate, site-identified containers, each is given a separate and independent Gleason score. When reviewing prostatectomy specimens, each individual nodule of tumor is given a Gleason score, identifying the index tumor nodule and all other independent nodules.