cystic breast disease vs cystic mastitis

cystic breast disease and cystic mastitis both are nouns.

Word	Noun	Adjective	Verb	Adverb
cystic breast disease	Yes	No	No	No
cystic mastitis	Yes	No	No	No

As nouns, cystic breast disease and cystic mastitis are synonyms defined as:

cystic breast disease and cystic mastitis: the presence of one or more cysts in a breast

Other synonyms of cystic breast disease include fibrocystic breast disease, fibrocystic disease of the breast.

cystic breast disease (noun)	cystic mastitis (noun)
the presence of one or more cysts in a breast	the presence of one or more cysts in a breast