age 51; 6'1''; 218lbs - generally good health. Noticed dry patch of skin in middle of back about a year and half ago. Over time, simply thought I was missing spot when placing lotion each morning. never paid much attention. The other day noticed the "spot" is larger and now moves down middle of back and kinda fans out on side of lower back on both sides. The upper middle is the worst. Dry itchy skin. Noticed a small similar spot the side of half dollar below check in middle of breastbone the other day. What could cause this?