Table of ContentsDefinition / general | Essential features | Pathophysiology | Etiology | Case reports | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Differential diagnosis | Board review style question #1 | Board review style answer #1
Cite this page: Garg S. Chorangiosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/placentachorangiosis.html. Accessed June 19th, 2021.
Definition / general
- Altshuler criteria: More than 10 capillaries in at least 10 terminal villi in 10 or more noninfarcted areas in at least 3 low power fields of the placenta (Arch Pathol Lab Med 1984;108:71); normal villi rarely have > 5 capillaries/villous
- Capillary hyperplasia is due to chronic placental hypoperfusion or low grade tissue hypoxemia (Gynecol Obstet Invest 2012;73:141)
- May be seen in pre-eclampsia, diabetes mellitus, placentomegaly, high altitudes, drugs and urinary tract infections
- Associated with neonatal morbidity / mortality
- Chorangiosis is a vascular hyperplastic process of the terminal chorionic villi, resulting from longstanding low grade hypoxia in the placental tissue (Congenit Anom (Kyoto) 2009;49:71)
- Alterations of the terminal villus lead to an abnormal growth of fibrous and vascular tissues, with an increased number of capillaries in placental areas
- Chronic hypoperfusion and tissue hypoxemia may lead to an excessive villous neoangiogenesis and to a high proliferative activity of connective tissue, probably mediated by growth factors (VEGF, bFGF and PDGF)
- Higher incidence in maternal pathological conditions such as preeclampsia, diabetes mellitus, drug ingestion and urinary tract infections
- Incidence is higher in women living at high altitudes, in maternal anemia and in women who smoke (J Pregnancy 2014;2014:193925)
- Also associated with placental alterations such as single umbilical artery, placental abruption, amnion nodosum, villitis and umbilical cord anomalies
- Complications include major fetal congenital anomalies or low Apgar index
- No distinct gross abnormalities
- Other placental findings may include: single umbilical artery and other umbilical cord anomalies, retroplacental hematoma (abruptio placentae) and placenta previa
Microscopic (histologic) description
- More than 10 capillaries in more than 10 terminal villi in at least 10 different noninfarcted areas in 3 low power fields of the placenta
- Capillaries have distinct basement membranes but are not surrounded by a continuous layer of pericytes or associated with stromal fibrosis
- May be associated with other features of villous dysmaturity, chorangioma, amnion nodosum, chronic villitis and fetal thrombotic vasculopathy (FTV)
- Must distinguish from congestion (vessels appear prominent but are normal in number) and tissue ischemia (has shrunken devitalized villi)
Microscopic (histologic) images
- Chorangioma: nodular lesion composed entirely of capillary vascular channels with surrounding trophoblasts; analogous to hemangiomas occurring elsewhere
- Chorangiomatosis: heterogeneous and less well defined lesion with intermediate features between chorangioma and chorangiosis
- Hyperplastic capillaries surround larger vessels in central cores of stem villi
- Increased number of perivascular bundles of reticulin fibers and pericytes
- Smooth mucle actin positive in pericytes
- Congestion: prominent capillaries in the villi but there is no numerical increase in the number of capillaries
Board review style question #1
Which of the following is true?
- Chorangiosis is also known as hemangioma of the placenta.
- Chorangiosis is always seen in women with diabetes mellitus, while chorangiomatosis is always seen in women with pre-eclampsia.
- In chorangiosis, each capillary shows a distinct basement membrane but there is no increase in perivascular pericytes or reticulin bundles.
- All of the above.
Board review style answer #1
C. In chorangiosis each capillary shows a distinct basement membrane but there is no increase in perivascular pericytes or reticulin bundles. Answer A is false because chorangioma, not chorangiosis, is known as hemangioma of the placenta. B is false because diabetes mellitus is associated with, but not always seen with chorangiosis.