Definition/General
Introduction:
Placental chorioangioma is a benign vascular tumor arising from the primitive chorionic mesenchyme
It is the most common non-trophoblastic tumor of the placenta
Small chorioangiomas (<5 cm) are clinically insignificant
Large tumors (>5 cm) may cause fetal complications
The incidence is approximately 1% of placentas.
Origin:
Arises from primitive angioblastic tissue in the placenta
Represents a hamartomatous proliferation of capillaries
May result from localized hypoxia
Genetic factors may contribute
Similar to capillary hemangiomas elsewhere.
Classification:
Classified by histological pattern: Angiomatous type (mature vessels)
Cellular type (immature capillaries)
Degenerated type (hyalinized)
By size: Small (<5 cm)
Large (>5 cm)
Giant (>10 cm).
Epidemiology:
Incidence: 1% of placentas
Small tumors: 0.5-1%
Large tumors: 0.02-0.2%
More common in multiple pregnancies
Female predominance (2:1)
Associated with advanced maternal age.
Clinical Features
Presentation:
Small tumors: asymptomatic
Large tumors: polyhydramnios
Fetal anemia
Congestive heart failure
Hydrops fetalis
IUGR
Preterm labor.
Symptoms:
Maternal symptoms: abdominal distension (polyhydramnios)
Fetal symptoms: decreased movements
Cardiotocography: abnormal patterns
Growth restriction
Preterm contractions.
Risk Factors:
Advanced maternal age
Multiple pregnancy
Diabetes mellitus
Previous chorioangioma
Familial history (rare)
High altitude residence.
Screening:
Prenatal ultrasound: well-defined mass
Doppler studies: high vascularity
MRI for large tumors
Fetal surveillance
Amniotic fluid assessment
Growth monitoring.
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Gross Description
Appearance:
Well-circumscribed mass on fetal surface
Dark red to purple color
Soft, spongy consistency
Pedunculated or sessile
Lobulated surface
Cut surface: honeycomb appearance.
Characteristics:
Smooth capsule
Rich vascular network visible
Hemorrhage and thrombosis possible
Calcification in older lesions
Cystic degeneration may occur.
Size Location:
Size: few mm to >15 cm
Location: usually fetal surface
May be subchorionic
Cord insertion site involvement
Rarely intraparenchymal.
Multifocality:
Usually solitary
Multiple tumors in 20% cases
Bilateral distribution possible
Associated with other placental abnormalities.
Microscopic Description
Histological Features:
Proliferation of capillaries and small vessels
Endothelial-lined spaces
Surrounding stroma variable
Immature mesenchymal tissue
Mitotic activity low
No cytological atypia.
Cellular Characteristics:
Endothelial cells: plump, benign
Pericytes present
Smooth muscle cells in vessel walls
Mesenchymal cells in stroma
No malignant features.
Architectural Patterns:
Angiomatous pattern: mature vessels
Cellular pattern: solid sheets of cells
Myxoid pattern: loose stroma
Sclerotic pattern: fibrotic areas
Combination patterns common.
Grading Criteria:
Type I (angiomatous): mature vessels
Type II (cellular): immature capillaries
Type III (degenerated): fibrotic, calcified
Vascular density assessment
Maturation grade.
Immunohistochemistry
Positive Markers:
CD31 (endothelial cells)
CD34 (vascular marker)
Factor VIII (endothelium)
Smooth muscle actin (pericytes)
GLUT-1 (vascular marker)
Ki-67 (low proliferation).
Negative Markers:
Cytokeratin (epithelial)
S-100 (neural)
Desmin (muscle)
CD68 (macrophages)
Trophoblast markers.
Diagnostic Utility:
Confirms vascular nature
Distinguishes from other tumors
Assesses proliferation rate
Rules out malignancy
Guides management.
Molecular Subtypes:
Capillary-type hemangioma
Cavernous-type hemangioma
Mixed-type lesion
Sclerosed variant.
Molecular/Genetic
Genetic Mutations:
VEGF pathway alterations
Angiogenesis genes
PDGF signaling
FGF pathway
Hypoxia-inducible factors.
Molecular Markers:
VEGF overexpression
PDGF-β expression
FGF-2 upregulation
Hypoxia markers
Angiogenic factors.
Prognostic Significance:
Size determines prognosis
Large tumors: poor fetal outcome
Small tumors: excellent prognosis
Associated complications
Recurrence rare.
Therapeutic Targets:
Observation for small tumors
Fetal surveillance
Early delivery if complications
Intrauterine interventions (selected cases)
Postnatal surgery rarely needed.
Differential Diagnosis
Similar Entities:
Teratoma
Partial mole
Placental mesenchymal dysplasia
Arteriovenous malformation
Subchorionic hematoma
Chorangiosis.
Distinguishing Features:
Chorioangioma: Benign vascular proliferation
Well-circumscribed
Teratoma: Multiple tissue types
Immature elements
Mole: Trophoblastic proliferation
Vesicular change.
Diagnostic Challenges:
Small lesions vs chorangiosis
Degenerated tumors
Calcified lesions
Clinical correlation important
Imaging correlation.
Rare Variants:
Atypical chorioangioma
Chorioangiomatosis
Angiosarcoma (malignant)
Hemangioendothelioma.
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
Placenta with chorioangioma measuring [X] cm
Diagnosis
Placental chorioangioma
Clinical History
[Polyhydramnios/fetal complications/incidental finding]
Gross Findings
Well-circumscribed [X] cm mass on fetal surface, dark red color
Microscopic Findings
Proliferation of capillaries and small vessels, benign endothelium
Tumor Characteristics
Size: [X] cm, Type: [angiomatous/cellular/degenerated]
Histological Type
[Angiomatous/Cellular/Mixed] type chorioangioma
Associated Complications
[None/Polyhydramnios/Fetal anemia/Other]
Prognosis
[Excellent/Good/Guarded] based on size and complications
Final Diagnosis
Placental chorioangioma, [X] cm, [type]