Two procedures will be coded.
Explanation:
According to the ICD-10-PCS coding guidelines B3 4b, which describes about biopsies and definitive treatments following that;
Any diagnostic procedure like biopsy (through excision, extraction or drainage) is followed by a definitive treatment like resection or destruction; then both the biopsy and the resection should be coded.
Hence in the above case, the biopsy sent for frozen section which is the diagnostic procedure and mastectomy which is the treatment procedure must be coded.
