Atypical Adenomatous Hyperplasia (Adenosis) of the Prostate: DNA Ploidy Analysis and Immunophenotype

Histopathology of Prostate Cancer and its Precursors

Starting in the mid-1970s, we formed a group of pathologists with a major interest in uropathology. Originally, it included 2 (R.M. and M.S.). In the years the followed, the group was enlarged to include 4 more people, 2 in the mid- and late-1980s (A.L.B. and L.C.) and another in the mid-1990s (R.Ma.); a sixth (A.C.) joined the group ∼5 years ago. Two have reached the retirement age (R.M. and M.S.), while others are in the process of joining the group to replace them. A fruitful collaboration spanned for ∼45 years. This contribution is based on a series of personal recollections of the successive changes in the interpretation of prostate cancer and its precursors, starting in the mid-1970s. Here we have retraced our involvement steps, sharing issues related to them with a junior uropathologist (A.C.).

Immunohistochemical expression of prostate tumour overexpressed 1 (PTOV1) in atypical adenomatous hyperplasia (AAH) of the prostate: additional evidence linking (AAH) to adenocarcinoma

BACKGROUND

Prostate tumour overexpressed 1, PTOV1, was recently identified as a novel gene and protein during a differential display screening for genes overexpressed in prostate cancer (PCa). It has been suggested that overexpression of PTOV1 can contribute to the proliferative status of prostate tumour cells and thus to their biological behaviour.

METHODS

PTOV1 and Ki67 were immunohistochemically evaluated in PCa, atypical adenomatous hyperplasia (AAH), high-grade prostatic intraepithelial neoplasia (HGPIN), and normal-looking epithelium (NEp) of the transition zone (TZ) in 40 radical prostatectomies with pT2a Gleason score 6 PCa (20 with AAH and 20 with HGPIN) and in 10 simple prostatectomies (SPs) (5 with AAH and 5 with HGPIN). The aim was to evaluate PTOV1 protein expression as a marker for tumor development and progression from AAH to PCa.

RESULTS

The proportions of PTOV1 and Ki67 positive cells increased from NEp through AAH and HGPIN to PCa. In particular, the mean Hscore of PTOV1 expression in AAH was 110.90, i.e., close to three times that of NEp (40.76), similar to that of HGPIN (105.61) and lower than that of PCa (137.03). The mean values in AAH and HGPIN associated with cancer in the RPs were slightly higher than in the SPs.

CONCLUSION

Our findings related to PTOV1 expression in AAH, similar to those in HGPIN, provide additional evidence linking AAH to prostatic adenocarcinoma.

Is atypical adenomatous hyperplasia of the prostate a precursor lesion?

BACKGROUND

Alpha-methylacyl-CoA racemase (AMACR) is highly expressed in prostatic adenocarcinoma. The precursor nature of atypical adenomatous hyperplasia (AAH) is uncertain.

METHODS

One hundred twenty-one AAH foci from 101 patients who underwent transurethral prostatic resection or prostatectomy were immunohistochemically analyzed for AMACR, high molecular weight cytokeratin 34βE12, and p63 expression by a triple antibody (PIN4) cocktail stain.

RESULTS

Sixty-eight foci (56%) of AAH showed no AMACR immunostaining. Fourteen cases (12%) showed weak AMACR immunoreactivity in 1-9% of lesional cells. Sixteen cases (13%) showed strong immunopositivity for AMACR in >50% of lesional cells. AMACR expression in AAH was significantly higher in cases in which coexisting PCA was present, compared with its expression in AAH foci without coexisting PCA (P = 0.03). Strong diffuse AMACR positivity in over 50% of lesional cells was seen almost exclusively in AAH foci with coexisting PCA (P = 0.002). AMACR expression in AAH showed no correlation with patient age (P = 0.38), specimen type (P = 0.35), prostate weight (P = 0.80), zonal location (P = 0.50), distance to cancer (P = 0.28), Gleason score (P = 0.06), or pathologic stage (P = 0.23). Increased AMACR expression showed a negative correlation with the size of AAH foci (P = 0.03). All AAH lesions showed fragmented basal cell layers, highlighted by p63 and high molecular weight cytokeratin staining.

CONCLUSIONS

A significant percentage of AAH cases show stronger and more extensive AMACR expression when associated with prostatic adenocarcinoma, as compared to AAH foci found without coexisting prostate cancer. Our data provide additional evidence linking AAH to prostatic adenocarcinoma.

Differences in the structural features of atypical adenomatous hyperplasia and low-grade prostatic adenocarcinoma

Aim

Atypical adenomatous hyperplasia (AAH) is a small glandular proliferation that has histological similarities with Gleason grade 1 and 2 prostatic adenocarcinoma (PACG1,2). There are no distinct histomorphological criteria distinguishing these two lesions from each other and other small glandular proliferations. Because treatment approaches are different for these lesions, it is necessary to determine histological criteria. The aim of this study is to review the histological features of these two lesions and to define new histological criteria distinguishing AAH from PACG1,2. We, therefore, assessed 18 anatomical and structural parameters.

Materials and Methods

We found 11 AAH (22 foci) and 15 PACG1,2 (22 foci) cases in 105 radical prostatectomy specimens. Basal cell-specific antikeratin was applied to these lesions. We assumed that PACG1,2 lesions did have not basal cells and we grouped the lesions as AAH and PACG1,2 based on this assumption.

Results

We found differences between AAH and PACG1,2 lesions for some parameters including the number of glands, structures such as the main ductus and basal cells. We found similar properties in the two lesions for the following parameters: localization, multiplicity, diameter of the lesion, focus asymmetry, distance between glands, inflammatory cells in and out of the lesions, secretory cell shape on the luminal side, papillary projection towards the luminal side of gland, the shape of the outer gland, the infiltrative pattern of the gland, glandular pleomorphism, biggest gland diameter and median gland diameter.

Conclusion

We determined that concurrent evaluation of histomorphological features was important to differentiate between AAH and PACG1,2.

Natural history of prostatic carcinoma: the pathologist's perspective

The stem (basal) cells of prostate acini are considered the origin of prostate cancer. Between these cells and the final secretory cells, different intermediate or transit cells can be observed, and every one of them can evolve into malignant cells, explaining the biological variability of prostatic cancer. The exact changes between normal gland and prostatic intraepithelial neoplasia (PIN) are not yet known, but a post-inflammatory atrophy lesion is being studied in this respect. The PIN lesion is considered the pre-invasive change of prostatic cancer and its presence in needle biopsy is clinically used for follow-up of the patient. The progressive knowledge of the stromal invasion in prostate cancer (loss of some cell-cell adhesion molecules and expression of others) can be correlated with the Gleason grading system, and the molecular changes in the progression to androgen-independent carcinoma can be used as a prognostic marker in conjunction with the classical pathological markers.

Current practice of Gleason grading of prostate carcinoma

The Gleason grading system remains one of the most powerful prognostic factors in prostate cancer and is the dominant method around the world in daily practice. It is based solely on the glandular architecture performed at low magnification. The Gleason grading system should be performed in needle core biopsies and radical prostatectomy specimens where it shows a reasonable degree of correlation between both specimens, and most importantly, it remains vital in the treatment decision-making process. This review summarizes the current status of Gleason grading in prostate cancer, incorporating recent proposals for the best contemporary practice of prostate cancer grading.