Neoplasm of uncertain behavior of breast

This code signifies a breast lesion where pathology has determined it is a neoplasm, but its biological behavior (whether it is benign or malignant) cannot be definitively classified at the time of diagnosis. It represents an intermediate category for growths that are not clearly benign but also lack definitive features of malignancy.

This code is appropriate when a biopsy or surgical excision of a breast mass reveals neoplastic cells, but the pathologist's report explicitly states "uncertain behavior" or "borderline malignancy." It should be used when there is insufficient information to classify the neoplasm as either benign (e.g., fibroadenoma) or malignant (e.g., carcinoma in situ, invasive carcinoma).

• Do not use this code if the pathology report clearly identifies the neoplasm as benign or malignant; instead, use the appropriate code from categories 217 (benign) or 174 (malignant).
• Ensure the documentation explicitly states "uncertain behavior" or similar terminology for a breast neoplasm.
• This code is often a temporary diagnosis while further diagnostic workup or observation is pending.