Histologic Criteria of Gleason Grading Patterns

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描述：Gleason grading system of prostatic adenocarcinoma

The histologic criteria for each of the Gleason grading patterns are as follows:

       Pattern 1. A well-circumscribed, tight cluster of uniform, separate, medium-sized glands with round or oval shape. There is no evidence of stromal invasion at the periphery of the rounded cluster of tumor acini (Fig. 7.22A).

The consensus of the ISUP Conference is that this pattern [1+1(2)] should not be diagnosed in any type of specimen except in very rare instances. It is most commonly observed in the transition zone of prostatectomy specimens in rare instances. Immunohistochemical staining for basal cell markers will allow the differentiation of adenosis (AAH), the benign lesion most closely resembling pattern 1 adenocarcinoma.

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描述：Pattern 1

       Pattern 2. The tumor acini are present in a circumscribed nodule, demonstrating less uniformity of size and shape, and more loosely packed than observed in pattern 1. Additionally, the peripheral leading edge of the tumor focus is more irregular, and may suggest minimal stromal invasion, a feature absent in pattern 1 (see Fig. 7.22B).

Pattern 2, like pattern 1, is rare, and is only infrequently confirmed in the subsequent prostatectomy specimen. The consensus at the ISUP Conference (2005) is that the diagnosis of Gleason 1 + 2 (3) to 2 + 2 (4) should “rarely if ever” be made on a needle biopsy. A diagnosis of Gleason score of 2 + 3 (5) or 3 + 2 (5) is more probably correct because of the infrequency of delineating the edge of the tumor site. A larger sample than is present in a needle biopsy may demonstrate an infiltrating border, and therefore a pattern of 2 would be excluded. A cribriform proliferation in pattern 2 is illustrated in the original Gleason diagram. Currently, this pattern of acinar proliferation is regarded as pattern 3 or 4 (discussed more completely in the subsequent text).

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描述：Pattern 2

       Pattern 3. Tumor acini in Gleason pattern 3 are generally smaller, with variation of shape and size than observed in patterns 1 and 2. Importantly, the tumor acini are discrete and separate, and they infiltrate the stroma accompanying benign prostatic acini. A cribriform pattern may be present, but are limited to glands that are the size of normal duct/acini and must show a smooth, round configuration (see Fig. 7.22C, D, E).

The criteria for pattern assignment of cribriform neoplastic proliferations in prostate adenocarcinoma is the most significant revision of the original Gleason grading protocol that was achieved by the 2005 ISUP Consensus Conference.

A cribriform proliferation that displayed irregular outlines and involved a focus larger than the normal ducts/acini is now regarded a form of Gleason pattern 4 and not pattern 3 as originally proposed by the Gleason protocol. True Gleason pattern 3 cribriform proliferations resemble cribriform HGPIN, and must be differentiated from the latter. The density and number of such cribriform proliferations in a focus (higher in adenocarcinoma), and the absence of basal cells determined by appropriate immunohistochemical staining will allow this differentiation.

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描述：Pattern 3-1

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描述：Pattern 3-2

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描述：Pattern 3-3

       Pattern 4. Pattern 4 proliferations demonstrate fusion of tumor acini, which are poorly defined glands with equally poorly delineated gland lumina. The fusion of tumor acini is the most common and most frequently overlooked feature allowing differentiation from Gleason pattern 3 (see Fig. 7.22F). Alternatively, cribriform proliferations, larger than normal ducts/acini, showing irregular peripheral outlines are currently defined as Gleason pattern 4, and not pattern 3 (see Fig. 7.22G, H). Finally, the “hypernephroid” form of prostate adenocarcinoma, originally described by the Gleason protocol, and resembling renal cell carcinoma, is uncommonly observed and designated pattern 4 .

       The recognition of the features of tumor acini with the Gleason pattern of 4 and the accurate

differentiation from Gleason pattern 3 cannot be overemphasized. The clinical behavior of prostatic adenocarcinoma with a component of Gleason pattern 4 (3 + 4 or 4 + 3) has been recognized from the first studies by Dr. Gleason and repeatedly confirmed. Indeed, the more aggressive clinical behavior of neoplasms with a primary pattern of 4 and a secondary pattern of 3 compared to the reverse (3 + 4), has been documented.1196,1197,1199,1203,1209 Therefore, the accurate differentiation of a Gleason 6 (3 + 3) from a Gleason 7 prostatic adenocarcinoma is critical for therapeutic and prognostic considerations. Further, the accurate quantification of the relative contributions of patterns 3 and 4 in adenocarcinomas with Gleason score 7 is critically important for the reasons noted earlier.

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描述：Pattern 4-1

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描述：Pattern 4-2

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描述：Pattern 4-3

       Pattern 5. The neoplastic proliferation comprises sheets, solid cords, or single cells devoid of gland formation, infiltrating the prostatic stroma. Alternatively, papillary, cribriform, or solid masses with true comedonecrosis is regarded as Gleason pattern 5 (see Fig. 7.22J, L).

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描述：Pattern 5-1. The neoplasm shows prominent comedonecrosis in the tumor masses

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描述：Pattern 5-2

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描述：Pattern 5-3