Prostate cancer with comedonecrosis is frequently, but not exclusively, intraductal carcinoma: a need for reappraisal of grading criteria

Aims Comedonecrosis in prostate cancer has always been Gleason pattern 5. However, we aimed to evaluate how intraductal carcinoma (not graded) with comedonecrosis should be considered. Methods and results From 52 radical prostatectomy patients, 40 were informative and evaluated with immunohistochemistry for basal cells. Clinical outcome was assessed for biochemical recurrence, metastatic disease and the need for adjuvant therapy. Comedonecrosis was predominantly located in intraductal carcinoma (24, 60%). However, nine (23%) had comedonecrosis within invasive cancer and seven (18%) within both invasive and intraductal carcinoma. Extraprostatic extension rarely showed comedonecrosis (5, 13%), but rather perineural invasion within cribriform glands. Tumours were largely high‐stage (15, 38% pT3a and 19, 48% pT3b), with 15 (37%) having positive lymph nodes and four distant metastases. Most cases (25, 63%) had other patterns of Gleason pattern 5 (single cells, solid), although 10 were reclassified as containing no invasive pattern 5. Of these, most were pT3 (eight of 10), but none had positive lymph nodes. Lymph node metastases were more common in patients with invasive cancer containing comedonecrosis (P = 0.02), and the need for androgen deprivation was near significance (P = 0.07), but biochemical recurrence was not significantly different (P = 0.58). Conclusions Prostate cancer with comedonecrosis is often intraductal; however, these tumours are largely high‐stage, showing a higher rate of positive lymph nodes with invasive comedonecrosis. Immunohistochemistry may be considered when comedonecrosis may significantly change the tumour grade. However, it is not clear at present that excluding intraductal carcinoma from the grade is superior to including it in grading when it is associated with high‐grade invasive cancer.