What are the usual symptoms of male breast cancer, and how often do patients not have the usual symptoms?

Male breast cancer. Hard lump behind nipple, non painful usually, sometimes the nipple will invert or have discharge, older male usually.
Changing lump. Breast skin issues more common, but male breast unusual. It used to be exclusively older men, but camp lejeune cluster in marines, family and vets suggest environmental toxin and younger age. If the lump has been there and has not changed, i'd worry less. If it is enlarging, red, and painful, see a surgeon. Cancer usually is not painful, but it needs removal and sent to path to analyze.