Serous borderline tumor (serous tumor of low malignant potential) is the most common borderline neoplasm of the ovary. It is characterized by papillary projections (papillary protrusions arising from the cystic wall or septa) within a cystic lesion — these papillary projections are the key diagnostic finding. Stromal invasion is ABSENT (distinguishing from invasive carcinoma). Peritoneal implants may be seen but are generally non-invasive (not desmoplastic). Prognosis is excellent — 5-year survival >95%. May be bilateral (25-40%). Generally diagnosed in premenopausal women (30-40 years). CA-125 may be mildly-to-moderately elevated. Surgical treatment is standard; fertility-sparing surgery is possible in young patients.
Age Range
20-50
Peak Age
35
Gender
Female predominant
Prevalence
Uncommon
Serous borderline tumor is a controlled proliferation of ovarian surface epithelium or tubal-type müllerian epithelium — unlike invasive carcinoma, stromal invasion (destructive growth) is ABSENT. The epithelium grows into the cyst cavity forming papillary structures — these papillary projections show irregular epithelial layering around a fibrovascular core. The fibrovascular core of papillary projections causes contrast uptake — this enhancing papillary projection is the fundamental imaging finding. Benign serous cystadenoma has NO papillary projections, while invasive carcinoma has solid components, deep stromal invasion, and more aggressive peritoneal spread. Peritoneal implants (non-invasive type) form through implantation of tumor cells onto peritoneal surfaces — but unlike invasive implants, they do not create desmoplastic reaction. The high bilateral rate (25-40%) suggests the tumor may reflect a widespread abnormality of müllerian epithelium.
Enhancing papillary protrusions arising from the cyst wall or septa within a cystic ovarian lesion. The fibrovascular core is bright with enhancement while surrounding fluid remains dark — the papillary projection emerges dramatically. This finding is ABSENT in benign serous cystadenoma (smooth thin wall, no papillary projections) and strongly suggests serous borderline tumor. Size, number, and enhancement intensity of papillary projections play a role in differentiating borderline from invasive carcinoma — invasive carcinoma is accompanied by larger, more extensive solid components and deep stromal invasion findings.
Papillary projections (polypoid protrusions) arising from the cyst wall or septa within a cystic lesion. Papillary projections are generally >3 mm in height, soft tissue echogenicity. Cystic component is anechoic (serous fluid). Septa may be present — thin or mildly thickened. Number and size of papillary projections are variable (single large or multiple small).
Report Sentence
Papillary projection(s) measuring ___ mm in height arising from the cyst wall/septa are seen within a ___ x ___ mm cystic lesion in the right/left ovary; serous borderline tumor should be primarily considered.
Vascularity within papillary projections can be demonstrated with Doppler — this confirms the presence of enhancing solid component. Vascular flow reflects the fibrovascular core. Minimal vascularity in cyst wall and septa. Vascularity in papillary projections provides additional evidence for differentiation from benign cystadenoma.
Report Sentence
Vascularity is seen within the papillary projection(s) on Doppler examination; presence of vascularized solid component is confirmed.
Papillary projections showing intermediate signal within a T2 hyperintense cystic lesion. Papillary projections are seen as polypoid structures arising from the cyst wall or septa. Cystic component shows hyperintense signal consistent with serous fluid. No T2 hypointense fibrous component (different from fibroma). Septa may be thin to mildly thick.
Report Sentence
Papillary projection(s) showing intermediate signal within a ___ x ___ mm hyperintense cystic lesion are seen in the right/left ovary on T2W.
Papillary projections show prominent enhancement on contrast-enhanced T1W — fibrovascular core contrast uptake. Cystic component does not enhance (fluid). Wall and septa may show thin enhancement. Enhancing papillary projection is the MOST IMPORTANT MRI finding for differential diagnosis from benign cystadenoma.
Report Sentence
Papillary projection(s) within the cystic lesion show prominent enhancement on contrast-enhanced T1W; finding consistent with serous borderline tumor.
Enhancing papillary components within a cystic mass on CT. Cystic component is near-water density (0-15 HU). Papillary projections show soft tissue density with prominent enhancement. Wall is thin to moderate thickness. Peritoneal implants may be seen as small peritoneal nodules or omental cake on CT (advanced stage).
Report Sentence
Enhancing papillary components within a ___ x ___ mm cystic mass are seen in the right/left adnexal region; careful evaluation for peritoneal implants is recommended.
Mild diffusion restriction may be seen in papillary projections (cellular structure). ADC values are intermediate. No diffusion restriction in the cystic component. More prominent diffusion restriction and lower ADC are expected in the solid component of invasive carcinoma.
Report Sentence
Mild diffusion restriction is seen in papillary projections on DWI with intermediate ADC values.
Criteria
Papillary projections, no stromal invasion, serous epithelial proliferation. Peritoneal implants may be present (non-invasive).
Distinct Features
Excellent prognosis (5-year survival >97%). Bilateral 25-40%. Peritoneal implants are non-invasive. Recurrence is rare (<5%).
Criteria
Micropapillary architecture (filiform, thin papillary structures showing branching). May show more aggressive biological behavior.
Distinct Features
Higher risk of invasive implants (30% vs typical 6%). Higher bilateral rate. More prominent and widespread papillary component on imaging. Increased risk of progression to low-grade serous carcinoma.
Criteria
Ovarian lesion is borderline but peritoneal implants are invasive (desmoplastic reaction, infiltrative pattern).
Distinct Features
Worse prognosis (5-year survival 65-85%). Invasive implants on CT/MRI appear as solid nodular peritoneal lesions, omental cake, mesenteric nodules. Requires more aggressive treatment.
Distinguishing Feature
Serous cystadenoma is thin-walled, unilocular, NO papillary projections, no enhancing solid component. In borderline tumor, papillary projections are present and prominently enhance. This distinction is critical for surgical decision-making.
Distinguishing Feature
Serous carcinoma shows prominent solid component (beyond papillary projections — large solid mass), deep stromal invasion, thick irregular wall, ascites, extensive peritoneal carcinomatosis, and omental cake. Borderline tumor is predominantly cystic with papillary projections but no large solid mass, no stromal invasion, limited and generally non-invasive implants.
Distinguishing Feature
Mucinous borderline tumor shows multilocular, stained-glass pattern (locules of different echogenicity), larger size, and mural nodules/thick septa. Serous borderline tumor has fewer locules, serous content (homogeneously anechoic), and papillary projections are prominent (rather than mural nodules).
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
6-monthSerous borderline tumor is a neoplasm of low malignant potential. Surgical treatment is standard — complete staging surgery (bilateral salpingo-oophorectomy, omentectomy, peritoneal biopsies, peritoneal wash cytology) or fertility-sparing surgery (unilateral salpingo-oophorectomy + staging) in young patients. Prognosis is excellent (5-year survival >95% in typical type). Postoperative follow-up with US + CA-125 at 6-month intervals. Micropapillary variant and invasive implants are poor prognostic factors. Chemotherapy is NOT indicated in typical borderline tumor — controversial in invasive implants. Gynecologic oncology consultation is recommended when papillary projection is detected.
Serous borderline tumors have excellent prognosis (>95% 10-year survival). Fertility-sparing surgery (cystectomy) is possible in young patients. Prognosis is unaffected when peritoneal implants are of non-invasive type.