Prostatic atrophy: its spatial proximity to carcinoma and intraepithelial neoplasia based on annotation of digital slides

Whether atrophy is a precursor to high-grade prostatic intraepithelial neoplasia (HGPIN) and cancer is controversial. A virtual slide set comprising 48 prostatectomy cases was used to investigate associations among the amounts and spacing of these entities. Foci of atrophy without inflammation (A), atrophy with inflammation (AI), cancer (by patterns), and HGPIN were digitally annotated. Atrophy's proximity to cancer and HGPIN was assessed with two measurements: abutment (touching) or nearness (≤2 μm without touching). Area sums per specimen were computed for A, AI, cancer, and HGPIN. Abutment rates of AI and A foci to cancer were 23% versus 21% (p = NS); for nearness, 29% of AI foci were near to cancer versus 12% of A (P = .0001). Abutment or nearness of A and AI to HGPIN were in the 1.4% to 2.4% range. When A, AI, or HGPIN abutted cancer, it was disproportionately to Gleason grade 3 cancer foci even after adjusting for the lesser frequency of higher-grade cancer foci. Area sums of A, AI, or (A + AI) per specimen showed no correlations with those of HGPIN, and mostly negative ones with area sum and with tumor volume of cancer. In conclusion, atrophy with inflammation showed some preferential spatial association to cancer, although area sums of atrophy with or without inflammation correlated negatively with those of cancer. These divergent spatial associations suggest that atrophy and inflammation in biopsy specimens may have clinical relevance. The frequency of inflammatory atrophy (AI) merging with HGPIN was far less than reported previously, weakening the theory that AI gives rise to HGPIN.