[1078] Ovarian Low Grade Serous Neoplasms: Evaluation of Sampling Recommendations Based on Tumors Expected To Have Invasion (Those with Peritoneal Invasive Low Grade Serous Carcinoma (Invasive Implants))

JD Seidman, JA Kraus, AV Yemelyanova, R Vang, BM Ronnett, RJ Kurman. Washington Hospital Center, Washington, DC; Johns Hopkins Medical Institutions, Baltimore, MD

Background: Exclusion of invasion in atypical proliferative (borderline) serous tumors (APST) depends on sampling adequacy. Previous recommendations of 1 section per cm (SPC) of maximum tumor diameter, and 2 SPC for tumors > 10 cm, have not been tested.
Design: 15 consecutive patients with 24 low grade serous neoplasms associated with invasive peritoneal carcinoma (9 bilateral) were evaluated for invasion on a section by section basis, with notation of which section per original submission order first showed invasion. Invasion < 5 mm was designated microinvasion, and > 5mm, low grade carcinoma. 5 patients' tumors were sampled with <1 SPC, and 10, > 1 SPC. Among the latter 10, 4 patients were sampled with >2 SPC.
Results: Invasion was identified in 11 of 15 patients (73%). At up to 1 SPC, 5 patients had APST, 5 had APST with microinvasion and 5 had low grade carcinoma. At up to 2 SPC, the diagnosis in two patients with APST (1 with microinvasion) was upgraded to carcinoma, and at >2 SPC, 1 additional APST with microinvasion was upgraded to carcinoma. Thus, increasing the sampling upgraded 3 of 10 patients with APST to carcinoma; only 8 of the latter 10 had been sampled at >1 SPC and therefore 3 of 8 (37.5%) APSTs were upgraded after increasing sampling to >1 SPC. All 3 tumors upgraded to low grade carcinoma had microinvasion in the earlier sections. 2 of 3 tumors upgraded to carcinoma were smaller than 10 cm. The mean sampling for tumors in which invasion was not found (n=6) was 0.8 SPC as compared to 1.9 SPC for tumors in which invasion was identified (n=18) (P<0.05, Student's t test).
Conclusions: 1 SPC is insufficient to adequately exclude invasion in APST. At least 2 SPC are needed, even for tumors smaller than 10 cm. Identification of microinvasion in APST is an important finding and should prompt submission of additional sections to exclude low grade carcinoma.
Category: Gynecologic

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 136, Wednesday Morning