Periacinar retraction clefting in the prostatic needle core biopsies: an important diagnostic criterion or a simple artifact?

The diagnosis of prostatic adenocarcinoma in needle core biopsy is based on major and supportive criteria. One of the supportive criteria is the presence of retraction clefting around neoplastic glands. We analyzed a series of 137 prostatic cancer cases diagnosed by needle core biopsy to determine the frequency, extent and criteria for periacinar retraction clefting. Clefting was analyzed on ten neoplastic and ten normal glands in three different high power fields. One-third or more glands with clefts affecting more than 50% of circumference were significantly more common in tumors (51.8%) than in benign glands (8%) (P<0.0001). A stricter criterion that designated as positive the cases with at least 50% of neoplastic glands (15 of 30) with clefts that affected more than 50% of circumference revealed clefts in only 15.3% of the malignant cases but none in benign cases (0%) (P<0.0001). Regardless of their extension, 15 or more glands with clefts were also more prominent in malignant cases (86.9%) than in benign cases (20.4%) (P<0.0001). We conclude that periacinar retraction clefting represents a reliable criterion for diagnosis of the prostatic adenocarcinoma, especially in cases with clefts affecting more than 50% of circumference in at least 50% of suspicious glands.