Heterogeneous clinicopathological features of intraductal carcinoma of the prostate: a comparison between "precursor-like" and "regular type" lesions

Abstract

Intraductal carcinoma of the prostate (IDC-P) has been described as a lesion associated with intraductal spread of invasive carcinoma and consequently aggressive disease. However, there are a few reported cases of pure IDC-P without an associated invasive component, strongly suggesting that this subset of IDC-P may represent a precursor lesion. We compared the clinicopathological features between the morphologically "regular type" IDC-P and "precursor-like" IDC-P. IDC-P was defined as follows; 1) solid/dense cribriform lesions or 2) loose cribriform/micropapillary lesions with prominent nuclear pleomorphism and/or non-focal comedonecrosis. We defined precursor-like IDC-P as follows; 1) IDC-P without adjoining invasive adenocarcinoma but carcinoma present distant from the IDC-P or 2) IDC-P having adjoining invasive microcarcinoma (less than 0.05 ml) and showing a morphologic transition from high-grade prostatic intraepithelial neoplasia (HGPIN) to the IDC-P. IDC-P lacking the features of precursor-like IDC-P was categorized as regular type IDC-P. Of 901 radical prostatectomies performed at our hospital, 141 and 14 showed regular type IDC-P and precursor-like IDC-P in whole-mounted specimens, respectively. Regular type IDC-P cases had significantly higher Gleason score, more frequent extraprostatic extension and seminal vesicle invasion, more advanced pathological T stage, and lower 5-year biochemical recurrence-free rate than precursor-like IDC-P cases. Multivariate analysis revealed nodal metastasis and the presence of regular type IDC-P as independent predictors for biochemical recurrence. Our data suggest that IDC-P may be heterogeneous with variable clinicopathological features. We also suggest that not all IDC-P cases represent intraductal spread of pre-existing invasive cancer, and a subset of IDC-P may be a precursor lesion.

Keywords: Prostate; high-grade prostatic intraepithelial neoplasia; intraductal carcinoma of prostate.

Figure 1

Precursor-like intraductal carcinoma of the prostate (IDC-P). (A) A case with a intraductal lesion having adjoining invasive microcarcinoma and showing recognizable morphologic transition from high-grade prostatic intraepithelial neoplasia (HGPIN) to IDC-P. (B) HGPIN component. (C) IDC-P component with dense cribriform pattern and necrosis. (D) Invasive microcarcinoma component with Gleason patterns 3 and 4. Immunohistochemical staining for high molecular weight cytokeratin highlighting the presence of basal cells in IDC-P component (E) and the absence of basal cell in invasive microcarcinoma component (F). Hematoxylin and eosin stain, original magnification ×20 for (A) and ×100 for (B-D). Immunoperoxidase stain, original magnification ×100 for (E and F).

Figure 2

Kaplan-Meier estimates of biochemical recurrence-free survival for 151 patients with intraductal carcinoma of the prostate (IDC-P), stratified by regular type or precursor-like IDC-P. Solid line curve for cases with regular type IDC-P (n = 137), and dashed line curve for cases with precursor-like IDC-P (n = 14).