Clinical Appearance of Purple Striae
Purple striae appear as violaceous (purple-red) linear bands on the skin, typically wide (>1 cm), with a characteristic distribution on the abdomen, thighs, breasts, and axillae, representing a highly specific clinical feature of hypercortisolism that should immediately prompt evaluation for Cushing syndrome. 1
Visual Characteristics
Unfortunately, I cannot provide photographs as none were included in the available medical literature. However, the clinical description is well-established:
- Color progression: Striae begin as erythematous (red) lesions called striae rubra, which appear violaceous or purple-red in lighter skin tones 2, 3
- Erythema index: Striae rubra demonstrate significantly higher erythema index measurements compared to striae alba (older, white stretch marks) and normal skin 3
- Skin brightness: Purple/red striae have significantly lower brightness values than both white striae and normal skin 3
- Width: In pathologic conditions like Cushing syndrome, striae are characteristically wide (>1 cm) 1
- Surface texture: The affected skin shows increased roughness compared to normal skin, with decreased elasticity and lower dermal echo-density 3
Anatomic Distribution Patterns
In Cushing syndrome specifically, purple striae appear in characteristic locations: 1
- Abdomen (most common)
- Thighs
- Breasts
- Axillae
- Supraclavicular region
Critical Diagnostic Context for Your Patient
In a 40-year-old woman on estrogen replacement therapy, purple striae are NOT typically caused by estradiol alone and should raise immediate concern for Cushing syndrome or exogenous corticosteroid exposure. 1 The key diagnostic considerations include:
Immediate Evaluation Required
- Exclude iatrogenic Cushing syndrome first: Review all medications for corticosteroid exposure, including inhaled/intranasal preparations, topical steroids, or systemic glucocorticoids 1
- Screen for endogenous hypercortisolism if no exogenous steroids identified, using one of: 24-hour urinary free cortisol (>4× normal strongly suggests Cushing), late-night salivary cortisol, or 1 mg overnight dexamethasone suppression test 1
Associated Clinical Features to Assess
Look specifically for: 1
- Centripetal obesity with supraclavicular fat pad and buffalo hump
- Proximal muscle weakness (difficulty rising from chair without using arms)
- Facial plethora and moon facies
- Hypertension and hyperglycemia
- Psychiatric disturbances or mood changes
Important Clinical Pitfall
Estrogen replacement therapy does NOT cause purple striae. 4 While striae distensae are associated with hormonal changes during pregnancy and puberty, therapeutic estradiol doses used in hormone replacement therapy do not produce the wide, purple striae characteristic of hypercortisolism 4. The presence of purple striae in your patient warrants investigation for an alternative etiology, particularly Cushing syndrome or undisclosed corticosteroid use.