Skin Disease
noun
Remember how you learned that 皮膚 is "skin?" Well when your skin is sick, you have a skin disease. You should probably go to a dermatologist right away.
ひふびょう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
息子は皮膚病を患っています。
My son suffers from a skin disease.