Pseudogynecomastia is definitively caused by an accumulation of adipose (fatty) tissue in the chest area, distinguishing it clinically from true gynecomastia, which involves the proliferation of glandular breast tissue.
The retrieved literature consistently distinguishes true gynecomastia (glandular tissue proliferation) from pseudogynecomastia. Papers explicitly define pseudogynecomastia as a condition characterized by deposits or accumulation of adipose tissue in the male breast/chest area.