[893] PINDCIS: Clinical Significance of Borderline Lesions between High Grade Prostatic Intraepithelial Neoplasm (HGPIN) and Intraductal Carcinoma of the Prostate (IDC-P) on Needle Biopsy

Jeong S Han, Stephen Lee, Jonathan I Epstein, Tamara L Lotan. Johns Hopkins Medical Institutions, Baltimore, MD

Background: Intraductal carcinoma of the prostate (IDC-P) and high grade PIN (HGPIN) exist along a morphologic spectrum. Distinguishing the two lesions is a common diagnostic dilemma with important clinical implications. While IDC-P is almost invariably associated with high grade invasive carcinoma and requires definitive therapy, HGPIN is frequently an isolated finding which may not even warrant re-biopsy. Here, we report on a group of borderline lesions we have designated as "PINDCIS," with morphologic features indeterminate between IDC-P and HGPIN.
Design: 53 prostate needle biopsies with isolated PINDCIS were identified from the consult files of one of the authors (JIE) between 2010 and 2011. PINDCIS lesions were characterized by 1) loose cribriform architecture beyond what would normally be seen in HGPIN, but lacking significant nuclear pleomorphism or necrosis to qualify for IDC-P; or 2) atypical nuclei with significant pleomorphism falling short of what is required for a diagnosis of IDC-P (<6 times larger than adjacent normal epithelial cells); or 3) dense cribriform to solid proliferation of atypical cells in incompletely represented large ducts on the edge of biopsy specimens. At the time of diagnosis, re-biopsy was recommended in all cases and clinical follow-up was successfully obtained in 41% (22/53) of patients.
Results: The median interval to re-biopsy for the 22 patients with clinical follow-up was 4 months (range: 0.6-16 months). On re-biopsy (or in one case, subsequent radical prostatectomy), 55% (12/22) of patients were diagnosed with prostatic carcinoma, with 83% (10/12) showing invasive tumor and 17% (2/12) showing definitive IDC-P. For patients with invasive tumor, 60% (6/10) had Gleason 6, 30% (3/10) had Gleason 7, and 10 % (1/10) had Gleason 8 tumor. Of the remaining patients, 40% (4/10) showed HGPIN on re-biopsy, 30% (3/10) showed PINDCIS, 20% (2/10) had a benign diagnosis and 10% (1/10) had a diagnosis of atypical glands, suspicious for prostatic carcinoma.
Conclusions: Borderline lesions between HGPIN and IDC-P are associated with a substantial increased risk (55%) of carcinoma on subsequent biopsy, with the majority of cases showing invasive carcinoma. Of cases with a subsequent diagnosis of invasive carcinoma, 40% showed Gleason score higher than 6, suggesting that many of these tumors are clinically significant. These lesions should be recognized and distinguished from ordinary HGPIN, and an immediate repeat biopsy should be recommended to rule out invasive carcinoma.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 2:15 PM

Proffered Papers: Section A, Monday Afternoon


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