A 30-year-old woman presents with episodic colour changes of her fingers: pallor on cold exposure, then cyanosis, then redness on rewarming. She has no digital ulcers, normal peripheral pulses, negative antinuclear antibody, and normal nailfold capillaries. Which feature best distinguishes primary from secondary Raynaud phenomenon?
- A Presence of abnormal nailfold capillaries ✓
- B Onset before the age of 40 years
- C Symmetrical involvement of both hands
- D Female preponderance
Correct answer: A. Presence of abnormal nailfold capillaries
Explanation
Abnormal nailfold capillaries indicate microvascular damage and point to secondary Raynaud phenomenon, typically due to systemic sclerosis or other connective tissue disease. Primary Raynaud features symmetrical bilateral involvement, onset in young women, normal capillaries, negative autoantibodies, and absence of tissue gangrene. Age of onset, female sex, and symmetry are all features of the primary form, so they cannot discriminate between the two entities.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.