What physical sign can differentiate primary from secondary Raynaud’s?

Abnormal nail fold capillaries with giant loops

In as many as 10% of individuals, Raynaud’s phenomenon (RP) is an early sign of a systemic rheumatic disease.

One should take a good history and complete physical evaluation including observation of nail fold capillaries (this may be done in the office with an ophthalmoscope), to evaluate for abnormality.

This is rarely remarkable in primary Raynaud’s phenomenon. Changes in the toes and ulceration of digit can occur in both primary and secondary Raynaud’s. Livedo reticularis, a mottling or reticular pattern seen in the limbs, can occur in both primary and secondary Raynaud’s and usually resolves with rewarming. Nonreversible livedo reticularis is seen only in secondary disease in association with other autoimmune rheumatic disorders.

Reference:

Wigley FM. Clinical manifestations and diagnosis of the Raynaud phenomenon. Updated January 2017. Accessed June 25th, 2017.