An official website of the United States government
Home
SEER Inquiry System - Report
Produced: 09/21/2026 12:11 AM
Question 20170043
Inquiry Details
References:
#1: WHO Class Female Genital Tumors, 38-41; 50-52. 5th edition
#2: Subject matter expert
Question:
Reportability--Ovary: Is ovarian mucinous borderline tumor of intestinal type (referred to as gastrointestinal type differentiation) with microinvasion reportable? If reportable, what is the histology? See Discussion.
Discussion:
4/18/17 Right ovary and fallopian tube, salpingo-oophorectomy: mucinous borderline tumor of intestinal type with microinvasion; greatest dimension 24.5 cm. Left fallopian tube and ovary, salpingo-oophorectomy: Benign ovary with multiple benign Mullerian inclusions. Benign fallopian tube with multiple paratubal cysts. Per pathology: pT1a pNx.
Answer:
Updated December 2025
For an ovarian mucinous borderline tumor, the term "microinvasion" is not an indication of malignancy according to the WHO Female Genital Tumors, 5th edition, and our expert pathologist consultant agrees. Therefore, borderline mucinous ovarian tumor with microinvasion is not reportable. Low malignant potential/borderline ovarian tumors are defined by the pathology of the primary tumor in the ovary, and microinvasion there, or invasion in implants does not change that diagnosis. The only exception is when the lymph nodes are positive for malignancy, the case is reportable. If the lymph nodes are positive for mucinous borderline tumor, the case is not reportable.
Similarly, serous borderline tumor with microinvasion, unless the morphology resembles low grade serous carcinoma and invasion measures <5 mm in a single focus, is not reportable.
