A 36-year-old woman presents with a 12-month history of progressive weight gain in the face, neck, and abdomen with paradoxical thinning of her limbs. She reports easy bruising, proximal muscle weakness, amenorrhea, and emotional lability. On examination, she has a rounded plethoric moon facies, a dorsocervical fat pad, central obesity with thin limbs, and the feature marked **D** in the diagram. Laboratory investigations confirm elevated late-night salivary cortisol and failure of suppression on 1-mg overnight dexamethasone test. Plasma ACTH is elevated. Which of the following best explains the pathophysiology of the feature marked **D**?

Question

Accepted Answer

A. Chronic excess glucocorticoid causes collagen breakdown and dermal atrophy, resulting in wide purple striae that distinguish Cushing syndrome from simple obesity. ## Why option 1 is correct

The feature marked **D** — wide violaceous (purple/red) abdominal striae — is a hallmark of Cushing syndrome and reflects the pathophysiologic consequence of chronic glucocorticoid excess. Excess cortisol causes profound collagen breakdown and dermal atrophy, resulting in striae that are characteristically **wide (>1 cm), purple or red in color, and violaceous** — in sharp contrast to the pale silver striae seen in simple obesity from rapid weight gain alone. These striae appear on the abdomen, thighs, flanks, and breasts and are among the most specific clinical features distinguishing true Cushing syndrome from other causes of obesity. This distinction is critical in the diagnostic approach to suspected hypercortisolism (Harrison's Principles of Internal Medicine, 21st Edition, Chapter 386).

## Why each distractor is wrong

- **Option 2**: While rapid weight gain does cause striae, these are typically **pale or silver in color** and result from mechanical stretching of the dermis. The **violaceous coloration and width >1 cm are specific to glucocorticoid-induced striae** and reflect collagen destruction, not simple mechanical stretch. This is the key distinguishing feature.

- **Option 3**: Although hyperandrogenism is present in Cushing syndrome (contributing to acne and hirsutism), it does not explain the formation of wide purple striae. Striae formation is a direct consequence of cortisol-induced collagen breakdown and dermal atrophy, not androgen-mediated pigmentation changes.

- **Option 4**: Malnutrition is not the primary driver of striae in Cushing syndrome. In fact, these patients typically have central obesity and are not malnourished. The striae result from the specific catabolic and collagen-degrading effects of excess glucocorticoids, not from nutritional deficiency.

**High-Yield:** Wide violaceous striae (>1 cm, purple/red) are the **most specific clinical feature distinguishing Cushing syndrome from simple obesity** and result from glucocorticoid-induced collagen breakdown and dermal atrophy.

[cite: Harrison's Principles of Internal Medicine, 21st Edition, Chapter 386: Disorders of the Adrenal Cortex — Cushing Syndrome]

Answer

B. Rapid weight gain from any cause leads to stretching of skin and formation of pale silver striae due to increased tension on dermal collagen

Answer

C. Elevated androgens in Cushing syndrome cause increased skin pigmentation and formation of dark striae through melanin deposition

Answer

D. Impaired wound healing from malnutrition results in fragile skin with striae formation independent of cortisol excess

Explanation

Why option 1 is correct

Why each distractor is wrong

Practice similar questions

Join our NEET PG community