fibrocystic breast disease vs fibrocystic disease of the breast

fibrocystic breast disease and fibrocystic disease of the breast both are nouns.

Word	Noun	Adjective	Verb	Adverb
fibrocystic breast disease	Yes	No	No	No
fibrocystic disease of the breast	Yes	No	No	No

As nouns, fibrocystic breast disease and fibrocystic disease of the breast are synonyms defined as:

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

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

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