Definition/General

Introduction:
-Ovarian adenoid cystic carcinoma is an extremely rare malignant tumor showing cribriform pattern similar to salivary gland tumors
-Represents less than 0.1% of ovarian malignancies
-Shows dual cell population (epithelial and myoepithelial)
-Contains pseudocystic spaces filled with basement membrane material
-Associated with MYB-NFIB fusion in some cases.
Origin:
-Arises from surface epithelium with dual differentiation
-May originate from inclusion cysts with metaplastic change
-Shows myoepithelial differentiation similar to salivary gland
-Results from MYB gene rearrangements (when present)
-Represents unique histogenetic pathway.
Classification:
-Classified under WHO 2020 as rare variant of surface epithelial tumor
-Low to intermediate grade typically
-Three histological patterns: cribriform, tubular, solid
-MYB-NFIB fusion characteristic (when present)
-FIGO staging follows standard protocols.
Epidemiology:
-Peak incidence in 5th-7th decades (40-70 years)
-Postmenopausal women predominantly
-Unilateral disease typical (>90%)
-Indolent behavior compared to other ovarian carcinomas
-Indian population shows similar age distribution
-Excellent prognosis when localized.

Clinical Features

Presentation:
-Slow-growing pelvic mass (most common)
-Incidental finding during routine examination
-Long symptom duration before diagnosis
-Early stage presentation typical
-Unilateral disease in >90%
-Minimal constitutional symptoms.
Symptoms:
-Mild pelvic discomfort (chronic)
-Abdominal bloating (gradual onset)
-Urinary frequency due to mass effect
-Minimal pain typically
-Normal menstrual cycles
-Slow progression of symptoms.
Risk Factors:
-Age >40 years
-No specific genetic predisposition
-Postmenopausal status
-No hormonal associations identified
-Environmental factors unclear
-Sporadic occurrence typical.
Screening:
-Transvaginal ultrasound shows solid mass
-CA-125 typically normal
-CT/MRI demonstrates solid tumor
-Tissue biopsy required for diagnosis
-Molecular testing for MYB rearrangement
-No specific serum markers.

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Gross Description

Appearance:
-Solid, well-circumscribed tumor
-Gray-white cut surface with firm consistency
-Smooth external surface
-Minimal necrosis or hemorrhage
-Homogeneous appearance on cut section.
Characteristics:
-Firm, rubbery consistency
-Gray-white to tan coloration
-Well-defined margins
-Solid architecture predominantly
-No cystic components typically
-Surface involvement rare.
Size Location:
-Size ranges from 3-12 cm (median 6 cm)
-Unilateral involvement >90%
-Can arise anywhere in ovary
-Well-localized tumor
-Bilateral disease extremely rare
-Confined to ovary typically.
Multifocality:
-Unifocal presentation >95%
-Bilateral involvement extremely rare (<5%)
-Extraovarian spread uncommon
-Lymph node involvement rare
-Peritoneal implants uncommon
-Indolent behavior.

Microscopic Description

Histological Features:
-Dual cell population: epithelial and myoepithelial cells
-Cribriform pattern with pseudocystic spaces
-Basaloid appearance
-Basement membrane material in spaces
-Perineural invasion may be present
-Minimal mitotic activity.
Cellular Characteristics:
-Small, uniform cells with minimal pleomorphism
-Basaloid morphology
-Dark, hyperchromatic nuclei
-Scant cytoplasm
-Dual cell types: luminal and abluminal
-Myoepithelial cells at periphery.
Architectural Patterns:
-Cribriform pattern (most common)
-Tubular pattern
-Solid pattern (high-grade areas)
-Pseudocystic spaces contain PAS-positive material
-Infiltrative growth at periphery
-Perineural invasion characteristic.
Grading Criteria:
-Low-grade (cribriform/tubular patterns)
-Intermediate-grade (mixed patterns)
-High-grade (solid pattern >30%)
-Mitotic activity low in most cases
-Nuclear pleomorphism minimal
-Solid component percentage determines grade.

Immunohistochemistry

Positive Markers:
-CK7 (luminal cells, 90-95%)
-PAX8 (85-90% cases)
-p63 (myoepithelial cells, 80-85%)
-Calponin (myoepithelial cells, 70-75%)
-SMA (myoepithelial cells, 60-70%)
-c-kit/CD117 (70-80%)
-SOX10 (myoepithelial cells, 50-60%).
Negative Markers:
-CK20 (negative)
-CDX2 (negative)
-TTF1 (negative)
-WT1 (typically negative)
-Calretinin (negative)
-Inhibin (negative)
-Chromogranin (negative).
Diagnostic Utility:
-Dual cell population IHC pattern diagnostic
-p63/calponin positivity in myoepithelial cells
-PAX8 positivity confirms ovarian origin
-c-kit positivity supportive
-CK7+/CK20- pattern typical
-SOX10 highlights myoepithelial component.
Molecular Subtypes:
-MYB-NFIB fusion positive subtype (when present)
-Low-grade molecular profile
-MYB overexpression
-Low Ki-67 proliferation (<10%)
-p53 wild-type pattern
-Unique transcriptional profile.

Molecular/Genetic

Genetic Mutations:
-MYB-NFIB translocation (when present)
-MYB gene rearrangements
-NOTCH pathway alterations
-TP53 mutations uncommon (<5%)
-PIK3CA mutations rare
-Low mutational burden overall.
Molecular Markers:
-MYB overexpression (majority of cases)
-MYB-NFIB fusion (subset)
-Low Ki-67 proliferation (<10%)
-p53 wild-type pattern
-SOX10 expression (myoepithelial cells)
-c-kit expression.
Prognostic Significance:
-Indolent behavior with slow growth
-Excellent prognosis when localized
-Stage at presentation most important factor
-Solid pattern associated with worse prognosis
-Perineural invasion may indicate aggressive behavior
-Local recurrence possible if incompletely excised.
Therapeutic Targets:
-c-kit inhibitors (imatinib) investigational
-NOTCH inhibitors experimental
-Standard chemotherapy limited efficacy
-Complete surgical resection curative
-Targeted therapy based on molecular profile
-Radiation therapy for local control.

Differential Diagnosis

Similar Entities:
-Primary ovarian carcinoid tumor
-Sex cord stromal tumor with cribriform pattern
-Metastatic adenoid cystic carcinoma (salivary gland)
-Sertoli cell tumor
-Granulosa cell tumor
-Small cell carcinoma.
Distinguishing Features:
-vs Carcinoid: Chromogranin negative
-Different architecture
-vs Sex cord: Inhibin/calretinin negative
-PAX8 positive
-vs Salivary metastasis: Clinical correlation
-PAX8 positive in ovarian
-vs Sertoli cell: Different IHC profile
-Lacks Call-Exner bodies.
Diagnostic Challenges:
-Extremely rare entity
-Morphological overlap with other small cell tumors
-Dual cell population may be subtle
-IHC panel essential
-Molecular confirmation helpful
-Clinical correlation required.
Rare Variants:
-Solid adenoid cystic carcinoma
-Adenoid cystic with clear cells
-Mixed adenoid cystic-serous pattern
-Cystic adenoid cystic carcinoma
-Each requires comprehensive workup.

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

Right/Left ovary and fallopian tube, measuring [X x Y x Z] cm

Gross Description

Solid, well-circumscribed [X] cm tumor with gray-white cut surface

Microscopic Description

Tumor with dual cell population showing [cribriform/tubular/solid] pattern with [grade] features

Immunohistochemistry

CK7: Positive (luminal), PAX8: Positive, p63: Positive (myoepithelial), c-kit: Positive

Diagnosis

Ovarian Adenoid Cystic Carcinoma, [Low/Intermediate/High] Grade, Stage [stage]

Final Diagnosis

Right/Left Ovarian Adenoid Cystic Carcinoma, Grade [X], FIGO Stage [X]