Definition/General
Introduction:
Ovarian cystadenomas represent the most common benign epithelial tumors of the ovary
They constitute 60-70% of all benign ovarian neoplasms
These tumors are characterized by cystic architecture lined by non-proliferative epithelium
They show no atypia and have excellent prognosis with complete surgical excision.
Origin:
Originate from the surface epithelium of the ovary or inclusion cysts
Develop from invagination of surface epithelium into ovarian stroma
The epithelium undergoes müllerian differentiation
No malignant potential when truly benign
Represent the benign end of the adenoma-borderline-carcinoma sequence.
Classification:
Classified by WHO 2020 guidelines based on epithelial type
Serous cystadenoma (most common, 60%)
Mucinous cystadenoma (25-30%)
Endometrioid cystadenoma (rare)
Clear cell cystadenoma (rare)
Brenner tumor (transitional cell type)
Mixed types possible.
Epidemiology:
Peak incidence in reproductive years (20-50 years)
Younger age than borderline and malignant tumors
Serous cystadenoma: 4th-5th decades
Mucinous cystadenoma: 3rd-4th decades
No specific ethnic predilection
Indian population shows similar age distribution with excellent outcomes.
Clinical Features
Presentation:
Asymptomatic in many cases (incidental finding)
Pelvic mass on examination
Abdominal distension (large tumors)
Pelvic pain (mild, intermittent)
Urinary symptoms (pressure effects)
No constitutional symptoms
Normal performance status
Fertility preserved.
Symptoms:
Pelvic discomfort or fullness
Mild abdominal pain
Urinary frequency (large masses)
Early satiety (very large tumors)
Bloating sensation
No weight loss or systemic symptoms
Regular menstrual cycles usually maintained
No hormonal effects.
Risk Factors:
No specific known risk factors
Reproductive age
Nulliparity (slight association)
Infertility treatment (ovulation induction)
Family history (minimal association)
Genetic factors (unclear significance)
Environmental factors (no clear association).
Screening:
No specific screening recommended
Routine pelvic examination
Transvaginal ultrasound for evaluation
CA-125 (usually normal, <35 U/mL)
Simple cyst criteria on ultrasound
Follow-up imaging for size monitoring
MRI for complex cases.
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Gross Description
Appearance:
Unilocular or multilocular cystic masses
Smooth external surface
Thin-walled cysts with clear or serous fluid
Serous cystadenoma: Clear, straw-colored fluid
Mucinous cystadenoma: Thick, viscous, mucoid content
No solid areas or papillary projections
Intact capsule.
Characteristics:
Size varies from 2-30 cm (average 10-15 cm)
Smooth, glistening surface
Translucent wall in serous type
Thicker wall in mucinous type
No excrescences or surface irregularities
Homogeneous fluid content
No areas of hemorrhage or necrosis.
Size Location:
Size typically 5-20 cm in diameter
Unilateral in majority (85-90%)
Bilateral occurrence: Serous (10-15%), Mucinous (<5%)
Mobile masses (not adherent)
Smooth contour
No ascites typically
Ovarian surface usually intact.
Multifocality:
Bilateral involvement uncommon
Multiple cysts within same ovary possible
No peritoneal involvement
No lymph node involvement
Contralateral ovary usually normal
Uterus and tubes typically uninvolved
No implants or seeding.
Microscopic Description
Histological Features:
Single layer of epithelial cells lining cyst wall
Bland cytology with no atypia
Uniform nuclei with regular contours
No mitotic activity
Serous type: Ciliated columnar epithelium
Mucinous type: Mucin-containing columnar cells
Fibrous stroma without proliferation.
Cellular Characteristics:
Epithelial cells show minimal variation in size and shape
Basally located nuclei
Abundant cytoplasm (mucinous type)
Cilia present (serous type)
No nuclear enlargement
No prominent nucleoli
No loss of polarity
Regular cell borders.
Architectural Patterns:
Simple cystic architecture
Single epithelial layer
No papillary formations
No solid areas
Smooth internal surface
Fibrous cyst wall
No complex branching
Uniform lining throughout.
Grading Criteria:
Cystadenomas are not graded as they are benign by definition
Assessment focuses on confirming benign features
Absence of atypia
No proliferative activity
Simple architecture
Exclusion of borderline features
No areas of concern requiring additional sampling.
Immunohistochemistry
Positive Markers:
CK7 (cytokeratin 7, positive)
PAX8 (müllerian origin marker)
WT1 (serous type, nuclear staining)
ER/PR (hormone receptors, variable)
CA-125 (serous type)
Calretinin (mesothelial marker, may be positive)
CK19 (cytokeratin 19).
Negative Markers:
CK20 (negative in serous, may be positive in mucinous)
CDX2 (negative in serous)
TTF-1 (thyroid transcription factor)
p53 (wild-type, scattered cells)
Ki-67 (very low proliferation index)
Inhibin (sex cord-stromal marker)
Chromogranin (neuroendocrine).
Diagnostic Utility:
PAX8 and WT1 confirm müllerian origin
CK7/CK20 profile helps in subtyping
Low Ki-67 confirms benign nature
p53 wild-type pattern
Negative sex cord markers exclude other tumors
Usually not necessary for straightforward cases
Helpful in differential diagnosis.
Molecular Subtypes:
Wild-type p53 (no mutations)
KRAS mutations (rare in benign cystadenomas)
BRAF mutations (absent)
PIK3CA mutations (rare)
Microsatellite stable
No significant mutations in most cases
Stable genome overall.
Molecular/Genetic
Genetic Mutations:
Very few mutations in benign cystadenomas
Wild-type p53 (>95% cases)
KRAS mutations (rare, <5%)
PIK3CA mutations (rare, <5%)
BRAF mutations (absent)
ARID1A mutations (rare)
Stable karyotype
No oncogene amplifications.
Molecular Markers:
p53 expression (wild-type pattern)
Ki-67 proliferation index (very low, <2%)
PTEN expression (intact)
MLH1/MSH2/MSH6/PMS2 (intact)
β-catenin (membranous pattern)
Cyclin D1 (low expression)
p16 (negative or weak).
Prognostic Significance:
Excellent prognosis (100% cure with complete excision)
No malignant potential when truly benign
No recurrence after complete removal
No impact on survival
Fertility preservation possible
No genetic counseling required
Routine follow-up sufficient.
Therapeutic Targets:
Surgical excision is curative
Conservative surgery (cystectomy) preferred in young patients
No adjuvant therapy required
No targeted therapy needed
Hormone therapy not indicated
Fertility-sparing surgery appropriate
Complete excision prevents recurrence.
Differential Diagnosis
Similar Entities:
Functional ovarian cysts (follicular, corpus luteum)
Borderline tumor
Invasive carcinoma
Endometriotic cyst
Tubo-ovarian abscess
Paraovarian cyst
Hydrosalpinx
Urachal cyst (rare).
Distinguishing Features:
Cystadenoma: Epithelial lining present
Cystadenoma: No atypia
Functional cyst: No epithelial lining or luteinized cells
Borderline: Epithelial proliferation and atypia
Endometriotic: Chocolate-colored content, hemosiderin
Abscess: Clinical signs of infection
Paraovarian: Separate from ovary.
Diagnostic Challenges:
Distinguishing from functional cysts (clinical correlation, follow-up)
Ruling out malignancy (imaging, tumor markers)
Bilateral vs unilateral disease assessment
Size criteria for surgical intervention
Age considerations (functional cysts more common in reproductive age)
Imaging characteristics crucial.
Rare Variants:
Papillary cystadenoma (benign papillary projections)
Adenofibroma (prominent fibrous component)
Cystadenofibroma (mixed cystic-solid)
Brenner tumor (transitional epithelium)
Clear cell cystadenoma (very rare)
Mixed müllerian cystadenoma.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Ovarian cyst, [left/right], measuring [size] cm
Diagnosis
Ovarian cystadenoma, [subtype]
Classification
WHO 2020: Benign epithelial tumor, [specific subtype]
Histological Features
Benign cystic tumor lined by [epithelial type] without atypia
Size and Extent
Size: [X] cm, confined to ovary
Margins
Surgical margins: [clear/involved]
Prognostic Factors
Excellent prognosis with complete excision
Final Diagnosis
Benign ovarian cystadenoma, [complete subtype]