always mean ordinary spoilage. One recognized cause is deep pectoral myopathy, also called green muscle disease or ischemic myopathy. This condition affects breast muscle tissue after its blood supply becomes restricted. As the damaged tissue changes, it can develop a surprisingly strong green color. The USDA says the various stages of ischemic myopathy do not themselves present a food-safety hazard to consumers. Ask USDA
However, you should never assume that every green patch has the same explanation. Spoiled poultry can also develop unusual appearance alongside unpleasant odors, stickiness, or slime.
