The rarest birthmark, according to the provided reference, is the port-wine stain.
While many types of birthmarks exist, some are more common than others. Vascular birthmarks, like hemangiomas, appear in 5 to 10 percent of newborns. Another common vascular birthmark is the stork mark. However, port-wine stains are significantly less frequent.
Rarity of Port-Wine Stains
The provided reference states that port-wine stains have an estimated incidence of only 0.3 percent in the population. This low incidence rate makes port-wine stains one of the rarer types of birthmarks.
Common vs. Rare Birthmarks
To better understand the rarity of port-wine stains, it's helpful to compare them to more common birthmarks:
| Birthmark Type | Incidence Rate | Relative Rarity |
|---|---|---|
| Hemangiomas | 5-10% | Common |
| Stork Marks | Common | Common |
| Port-Wine Stains | 0.3% | Rare |
Understanding Birthmarks
Birthmarks are skin markings that are present at birth or develop shortly after. They can vary in color, shape, and size. There are two main types of birthmarks:
- Vascular Birthmarks: These are caused by abnormal blood vessels and include hemangiomas, stork marks, and port-wine stains.
- Pigmented Birthmarks: These are caused by changes in the skin's pigment cells and include moles and café-au-lait spots.
Summary
Port-wine stains are considered the rarest among the birthmarks mentioned in the reference, occurring in only 0.3% of the population.
