Types of stretch marks
Associated with their formation and appearance, stretch marks can be broken down into two main stage classifications:
- Striae rubrae: Pink / red stretch marks
- Striae albae: White stretch marks
Other classification types are:
- Striae gravidarum: Stretch marks which occur as a result of pregnancy.
- Striae nigrae: Dark grey or black stretch marks (usually applicable to darker complexion skin types).
- Striae caerulea: Dark blue / purplish stretch marks (also applicable to those with darker complexions).
- Striae atrophicans: Thinned skin associated with stretch marks – this may develop in those with Cushing’s syndrome, due to the prolonged use of corticosteroids or after a surgical procedure.
Striae rubrae is classified as the acute stage of stretch marks which presents the earliest physical indications of overstretched skin. The epidermis typically flattens (due to gradual atrophy / degeneration) and experiences a loss of rete ridges. Collagen fibres thicken and become more densely packed, arranging themselves in a more perpendicular or parallel pattern. The number of elastic fibres also decreases.
Signs of inflammation due to overstretching are most apparent at this stage and the affected skin turns pink / red or violaceous in colour. Markings may appear flat but can sometimes be slightly raised too. Formations gradually increase in both length and width. At this stage, stretch marks can also become pruritic (itchy) but are predominantly asymptomatic.
Striae albae is classified as the more chronic (or mature) stage of stretch mark formation. Here stretch marks become more scar-like, irregularly shaped and hypopigmented (faded / white – losing vascular alterations). Some may even develop a fine wrinkly texture. Progression from striae rubrae to striae albae is gradual and can take several months to years. Mature stretch marks may also become more prominent as a person naturally loses skin elasticity through the process of aging.
Striae gravidarum are classified as secondary to striae distensae and develop as a result of pregnancy. Stretch marks are most prominent on the abdomen, breast and thigh areas of a pregnant woman, typically occurring around the 6th or 7th month of gestation but can also occur as early as 24 weeks. (1) A pregnant woman may also note stretch mark formations around her lower back area, upper arms, hips and buttocks. These stretch marks begin as striae rubrae and evolve into linear hypopigmented depressions, often with fine wrinkles.
A reduction in or weakening of elastin fibres and fibrillin microfibrils (a glycoprotein) in the dermis is mostly attributed to the physical and hormonal changes experienced during pregnancy. This may account for the change in the display pattern of stretch marks in pregnant women – which have a more parallel pattern (often developing side-by-side) rather than perpendicular alignment.
Stretch marks acquired during pregnancy do tend to fade, becoming more mature within a year or two (postpartum). For the most part, stretch marks do not disappear completely.
1. US National Library of Medicine National Institutes of Health. June 2017. Striae gravidarum: Risk factors, prevention, and management: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440454/ [Accessed 26.02.2018]