PATHOLOGY

Positive surgical margins in areas of capsular incision in otherwise organ-confined disease at radical prostatectomy: histologic features and pitfalls
Chuang AY, Epstein JI
Department of Pathology, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan
Am J Surg Pathol. 2008; 32: 1201-6

• Capsular incision (CI) refers to the urologist transecting either benign or malignant prostatic tissue, where the edge of the prostate in this region is left within the patient. Histologic assessment of CI is difficult and its diagnosis varies among pathologists. Between 1993 and 2004, we reviewed 186 radical prostatectomies that were signed out as either: (1) CI into tumor in otherwise organ-confined disease [elsewhere no extra-prostatic extension (EPE), seminal vesicle invasion, or lymph node spread] (n = 143); (2) positive surgical margin in an area difficult to distinguish EPE from CI into tumor in otherwise organ-confined disease (n = 36); or (3) equivocal positive surgical margin in an area difficult to distinguish organ-confined disease with tumor close to resection margins (OC M-) from CI into tumor in otherwise organ-confined disease (n = 7). On review, CI with a positive margin was confirmed in 83.2% of cases. Of cases signed out with margins positive where it was difficult to distinguish CI from EPE, CI was confirmed in 52.8% of cases. Cases with equivocal positive margins with either CI or OC M- were considered CI with positive margins in 57.1% of cases on review. Cases in all 3 groups not considered positive margins with CI were on review equally divided between diagnoses of organ-confined margin negative and EPE with positive margins. The locations of the 39 cases originally misdiagnosed as definitive or questionable CI with positive margins were posterolateral (N = 19, 48.7%), distal (N = 12, 30.8%), posterior (N = 6, 15.4%), and anterolateral (N = 2, 5.1%). Familiarity with different patterns of EPE in different anatomic locations and applying strict criteria for diagnosing CI into tumor can minimize overcalling CI and can provide accurate feedback to urologists to prevent iatrogenic positive margins.
  
  
• Editorial Comment
  Positive surgical margin (vesical, urethral or circumferential) in radical prostatectomy specimens is a well established adverse finding for biochemical (PSA) progression following surgery. The frequency of this progression varies from 36% to 72% in the literature (1). In our Institution, the progression in 300 patients was 37% after 5 years of follow-up.
  It is important for the urologist the definition and the description of the several kinds of positive surgical margins (2):
  a) Positive surgical margins are defined as cancer cells touching the inked surface of the prostate;
  b) Iatrogenic surgical margin occurs whenever there is a transection of the intraprostatic tumor. If this occurs, one cannot determine whether there is extraprostatic extension in the region of incision into the prostate as the edge of the prostate has been left in the patient. Unless there is extraprostatic extension in other areas of the surgical specimen, the pathologic stage is called pT2+;
  c) Non-iatrogenic surgical positive margin occurs whenever there is an inability to widely excise tumor showing extraprostatic extension.
  It is worth mentioning the possibility of positive surgical margins in normal prostatic glands. This is not routinely reported by the pathologist; however, it is very important to report in cases of limited carcinoma in the surgical specimen. In these cases, biochemical (PSA) progression following surgery may be due to normal glands left in the patient. In our Institution, no patient with limited carcinoma in the specimen had biochemical progression, except 3 patients. Reviewing the prostatectomy slides, we found that all 3 patients had frequent and extensive positive surgical margins in normal glands.

References
1. Epstein JI, Amin M, Boccon-Gibod L, Egevad L, Humphrey PA, Mikuz G, et al.: Prognostic factors and reporting of prostate carcinoma in radical prostatectomy and pelvic lymphadenectomy specimens. Scand J Urol Nephrol Suppl. 2005; 216: 34-63.
2. Billis A, Watanabe IC, Costa MV, Telles GH, Magna LA: Iatrogenic and non-iatrogenic positive margins: incidence, site, factors involved, and time to PSA progression following radical prostatectomy. Int Urol Nephrol. 2008; 40: 105-11.

Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil
E-mail: athanase@fcm.unicamp.br