Significance of Prostatic Atypical Small Acinar Proliferation in Surgical Pathology Quality Assurance
Michael Van Ness, Olivia Lee, Marc Dall'Era, Regina Gandour-Edwards. UC Davis, Sacramento, CA
Background: Atypical small acinar proliferation (ASAP) in the prostate has emerged as a significant lesion. Multiple authors have demonstrated that ASAP confers an average 40% risk of eventual prostate cancer. Urologic practice recommends an immediate repeat biopsy. The frequency of ASAP in large prostate biopsy series varies from 1-23% with an average of 5%. The k value of expert pathologists regarding ASAP ranges from 0.29-0.49 and the k value for general pathologists is 0.14-0.27.
Design: Utilizing appropriate IRB/HIPAA guidelines, we reviewed patients with ASAP for the five year period 2007-2011. These were ultrasound guided 12-14 core specimens. Our protocol performs three level sections with H&E staining of levels 1 and 3. Level 2 is utilized for triple stain immunohistochemistry as needed. Forty six biopsies were reviewed by two pathologists who were unaware of the original diagnosis. The reviewer choices were ASAP, negative (benign) or carcinoma.
Results: ASAP was diagnosed on 5.3% of biopsies between 2007-2011 with a range of 2.8-7.9%. The average total biopsies performed was 280 per year. Twenty three patients had follow up biopsy. The followup results were: 16 (70%) negative/benign; 6 (26%) ASAP and 1 (4%) carcinoma. Immunohistochemistry was utilized in 40% of these.
Cohen's kappa (k) coefficient, a statistical measure of inter-rate agreement, was applied to quantify significant agreement or differences between the two reviewing pathologists and the original diagnosis. The k value between reviewer 1 and reviewer 2 was 0.57; between reviewer 1 and original diagnosis 0.42 and between reviewer 2 and original diagnosis 0.45.
Conclusions: Our findings demonstrate acceptable agreement between both reviewers and original diagnoses and is comparable to previous studies. Our incidence of ASAP is also comparable. The low rate of subsequent cancer is likely due to our short period of followup. We intend to follow these patients for the next 3 years. We propose that the rate of ASAP with patient outcome be performed as part of quality assurance as a monitor of resource utilization. With the evolving health care environment, surgical pathologists have an important role to define markers of value for health outcomes.
Category: Genitourinary (including renal tumors)
Wednesday, March 6, 2013 9:30 AM
Poster Session V # 118, Wednesday Morning