Pathologic findings:
Consist of four strips of whitish tissues measuring 0.4 to 2.0 cm long
each. Submitted entirely in one block. Sections show strips of fibromuscular
stroma containing a few residual prostatic glands but several foci of tumour
tissues are also seen. These consists mostly of solid aggregates of clear
cells with only a few acinar glands within them. This pattern corresponds
to that of a Gleason grade 4 area. The tumour cells have hyperchromatic
nuclei. Occasional nucleoli are seen. In small areas, a more infiltrative
pattern consistent with Gleason grade 5 pattern are seen.
| Figure 1: Low power view. Grade 4 area. | Figure 2: Medium power view. Grade 4 area. | Figure 3: High power view. Grade 4 area. | Figure 4: Low power view. Grade 5 area. |
| Figure 5: Medium power view. Grade 5 area. | Figure 6: High power view. Grade 5 area. |
Pathologic Diagnosis:
Transrectal biopsy - Prostatic adenocarcinoma. Gleason score 4+5=9.
Pathologist Comments:
This is a needle biopsy and presuming the features are representative of the entire tumour, the tumour has a poor prognosis due to the presence of high grade areas. Grading is based on a scheme originally proposed by Gleason. He proposed grading be entirely based on the pattern and degree of glandular formation and five patterns are recognized. This is called the Gleason grading system. The most extensive (primary area) and the second most extensive patterns (secondary area) are combined to give the Gleason Score (e.g. 4+5=9 in this case). There is a minimum score of 2 and a maximum score of 10. This case thus has a high Gleason Score of 9 which indicates poor prognosis. The subsequent development of bone metastasis is consistent with the Gleason score.
However, Gleason Score sometimes do not entirely reflect the prognosis as it only considers the tumour pattern (i.e. degree of glandular formation) without taking into account of the cellular differentiation. Also, it only considers the two most predominent tumour pattern. Thus a tumour that has predominantly two low grade patterns but also having small foci of high grade areas may have poor prognosis. Also, tumour cells with marked cellular anaplasia but having extensive glandular formation may have a poorer prognosis despite a relatively low Gleason score.
Microscopic grading had been found to correlate with PSA levels, clinical and pathological staging, incidence of lymph node and bone metastasis. Tumours with scores of 2 to 4 are almost never aggressive. In tumours with scores of 8 to 10, most patients die of the disease.
Invasion of the 'capsule' (i.e. the outer fibromuscular layer of the prostate) is very common. In one study, the propabality of the tumour having extended outside the prostate was found to be zero if the 'capsular' margin was negative, 12% if it was equivocal and 60% if it was positive. Additional factors that influence prognosis are tumour bulk. Partin tables are designed to take into account of Gleason score as well as tumour bulk. The tumour bulk can be estimated using the serum PSA levels or volumetric methods in total prostatectomy specimen. The latter method is obviously very time consuming..
The most common sites of metastatic spread are the bone and lymph nodes.
Bone metastasis are characteristically sclerotic rather than osteolytic.
The most common bones involved are the lumbar spine, sacrum and pelvis.
The incidence of lymph node metastasis is related to clinical staging,
volume of tumour, PSA levels and grade.
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