Behavior--Prostate: What is the correct behavior of intraductal carcinoma from a prostate biopsy with a Gleason score 4+4=8. While highly aggressive, but not suggestive of invasion, coding behavior as /2 seems inappropriate.
WHO classifies intraductal carcinoma of the prostate 8500/2. According to WHO, "the hallmark of intraductal carcinoma of the prostate is a proliferation of prostate carcinoma cells that is within and may significantly expand the native prostatic ducts and acini, with the basal cell layer at least partially preserved." Further, differentiation between intraductal carcinoma and infiltrating high-grade carcinoma of the prostate may require basal cell stains. Under Prognosis, WHO states: " intraductal carcinoma of the prostate on prostate biopsies is often associated with high-grade cancer (with a mean Gleason score of 8) ."
So while it may seem counter-intuitive, assign behavior code /2 when the diagnosis is intraductal carcinoma of the prostate.
Behavior--Breast: How is behavior coded when a biopsy shows in situ carcinoma with a focus suspicious for invasion and a subsequent excision/resection shows only in situ carcinoma?
Code this case as in situ. The specimen from the excision/resection is the more reliable source for determining behavior, compared to a biopsy, especially in this case where the behavior is ambiguous on the biopsy.