The term “strawberry mark” is the common name for an Infantile Hemangioma (IH), the most frequent benign tumor seen in infants and children. This vascular growth is characterized by an abnormal clustering of blood vessel cells that typically appears within the first few weeks of life, rather than being present at birth. IH affects an estimated 5% to 10% of all infants worldwide. While these growths are non-cancerous, their appearance and rapid growth phase often prompt parental concern and medical evaluation.
Appearance and Types of Hemangiomas
The visual presentation of an infantile hemangioma depends largely on its depth within the skin layers. A superficial hemangioma, the classic “strawberry mark,” is bright red, raised, and bumpy because it develops on the skin’s surface. These well-defined lesions are frequently found on the head and neck, though they can appear anywhere on the body.
When the abnormal cell growth occurs deeper, beneath the skin, it is classified as a deep hemangioma. This type may present as a bluish or skin-colored, lumpy mass. The blue tint results from the deeper location of the blood collection, which affects how light is reflected. A third classification is the compound or mixed hemangioma, which involves components of both the superficial and deep types. This lesion has both a bright red, raised surface and an underlying bluish or subcutaneous swelling.
The Biological Mechanism Behind Their Formation
The underlying cause of infantile hemangioma involves a localized, excessive proliferation of endothelial cells, which line the inside of blood vessels. This rapid growth phase distinguishes IH from other vascular malformations. Scientists believe this cellular overgrowth is triggered by a combination of genetic predisposition and specific signaling pathways that become dysregulated shortly after birth.
One widely accepted theory points to localized tissue hypoxia, or low oxygen, which is often associated with IH risk factors. This lack of oxygen is thought to induce the overexpression of potent angiogenic factors, such as Vascular Endothelial Growth Factor (VEGF) and basic Fibroblast Growth Factor (bFGF). These factors promote the growth and formation of new blood vessels, leading to the rapid expansion of the hemangioma.
The cells that make up the hemangioma express a specific marker called glucose transporter-1 (GLUT-1), which is not found in other vascular tumors. This unique characteristic suggests that hemangiomas may originate from placental tissue remnants or endothelial progenitor cells that embolize from the placenta during pregnancy. This theory posits that the hemangioma cells are essentially placental cells that mistakenly lodge in the infant’s skin, leading to post-natal growth. Defects in the vascular endothelial growth factor receptor complex in these cells can also lead to constitutive, or unrestrained, VEGF signaling, further fueling the abnormal proliferation.
Who Is Most Likely to Develop a Hemangioma
While the exact trigger for the cellular mechanism remains unclear, several demographic and perinatal factors are statistically associated with developing infantile hemangioma. Prematurity is a significant factor, with infants born before 37 weeks having a substantially higher risk compared to full-term babies. Similarly, a low birth weight (less than 2,500 grams) is strongly correlated with IH occurrence.
The risk of hemangioma increases in cases of multiple gestations, such as twins or triplets. There is a notable female predilection, with girls being affected approximately three to four times more often than boys. Certain maternal and placental conditions, including preeclampsia, placenta previa, and advanced maternal age, are also considered risk factors for IH development.
Natural Course and Management Options
Infantile hemangiomas follow a predictable, generally self-limiting three-phase life cycle. The first is the proliferative phase, where the lesion undergoes rapid growth, typically peaking between four and nine months of age. This is followed by a plateau phase, where growth stabilizes before the lesion enters the involution phase.
Involution involves the slow regression and shrinking of the hemangioma, as abnormal endothelial cells are replaced by fibro-fatty tissue. This regression can take several years, often continuing until a child is five to ten years old. Most lesions resolve without intervention. However, medical intervention is necessary for a subset of hemangiomas, particularly those that impair function (such as lesions near the eye or airway) or those that have developed ulceration or bleeding.
The first-line treatment for problematic hemangiomas is oral propranolol, a type of beta-blocker medication. Propranolol accelerates involution by causing blood vessels to constrict and inhibiting the growth of endothelial cells. For smaller, superficial lesions, topical beta-blockers like timolol may be used. Early diagnosis and treatment prevent permanent scarring or disfigurement, especially for hemangiomas in cosmetically sensitive areas.