breast neoplasm
I grabbed my 2013 CHONC study manual to answer this question (page 12).
A common neoplasm coding error is determining between unspecified and uncertain behavior. Uncertain behavior is described in ICD: Categories 235-238by site certain histomorphologically well defined neoplasm, the subsequent behavior of which cannot be predicted from the present appearance.
Histomorphologically means that you can only use those codes if a physician - your physician or a pathologist - has examined the tissue under a microscope and determined that the tissue is ambiguous and cannot be assigned a malignant or benign designation. Codes from that category cannot be assigned if no microscopic examination has occurred. Instead, unspecified codes should be used if the claim must be filed before a pathology report is issued.
I hope this helps clarifies the difference.
Thanks,
Dana Chock, CPC, CCA, CANPC, CHONC
Anesthesia, Pathology, & Laboratory