Intravital detection of skin capillary aneurysms by videomicroscopy with indocyanine green in patients with progressive systemic sclerosis and related disorders. Conventional capillaroscopy and infrared fluorescence videomicroscopy with indocyanine green were performed at the nailfold in 12 healthy controls and 38 patients with microangiopathy due to systemic sclerosis or related disorders. Saccular aneurysms featuring head and neck (type 1) and aneurysmatic enlargements (type 2) were defined. Microaneurysms were located at the apex or near the apex of capillary loops and were significantly more common in patients than in controls (p less than 0.02 for type 1 and p less than 0.001 for type 2). Combination of the two lesions was found only in patients and appears to be a valuable new diagnostic sign for the presence of microangiopathy. In comparison with conventional capillaroscopy, about twice as many microaneurysms were detected by videomicroscopy with indocyanine green coupling almost completely to plasma proteins. The new technique allows visualization of capillary aneurysms even when filled only by plasma. 