Abstract One of the most striking features of the adipose depot surrounding the prostate [periprostatic adipose tissue (PPAT)] is that its accumulation is independent of body mass index. Its volume varies considerably between individuals, with some patients exhibiting abundant PPATs, which have been correlated to the occurrence of aggressive prostate cancer (PCa). However, abundant PPAT is not well defined at the biological level. We used a new statistical approach to define abundant PPAT by normalizing PPAT volume to prostate volume in a cohort of 351 patients using a linear regression model. Applying this definition, we confirmed the link between abundant PPAT and PCa aggressiveness, thereby validating our approach. At the biological level, we showed that abundant PPAT exhibited extensive extracellular matrix remodeling, notably of the collagen network, decreasing the mechanical constraints in hypertrophic adipocytes, leading to inflammation‐free expansion. Degradation of the most abundant collagen in adipose tissue (AT), collagen VI, was associated with increased production of endotrophin, a signaling peptide derived from AT that was also elevated in the urine of patients with abundant PPAT confirming the clinical relevance of our results. These results highlight a unique mechanism of expansion of an adipose depot and open new mechanistic avenues to explain its role in prostate‐related disorders. © 2026 The Pathological Society of Great Britain and Ireland.