Microangiopathy is a primary clinical feature of systemic sclerosis (SSc), and nailfold videocapillaroscopy (NVC) is the standard tool to detect morphological capillary abnormalities. NVC may discover the “Early” pattern of microangiopathy, monitor its progression, inform on disease status, and also predict future organ involvement. NVC has been proposed as possible biomarker in SSc, correlating the capillary damage extent with the internal organ involvement (1–3).
SSc patients show pathognomonic capillary abnormalities, which characterize the scleroderma-pattern of microangiopathy (2,4,5). Among these, giant capillaries (dilation of both capillary branches >50 microns), microhaemorrhages, reduction of capillary number (below 9 per linear millimetre), ramified (neoangiogenic) capillaries and disorganization of the vascular array are the major capillary abnormalities. These abnormalities do not occur all together at the same time, but sequentially, and three different patterns of nailfold microvascular damage (“Early”, “Active” and “Late” scleroderma-patterns) have been proposed and validated in SSc patients (4–8). As a matter of fact, in some patients the capillary pattern remain unchanged for several years, whereas other patients show a fast evolution of the microangiopathy in a few months or years, along with progressive internal organ involvement (8,9). The factors influencing the time of evolution of the microangiopathy from the “Early” to the “Late” stage have not yet been determined.
To score SSc capillary abnormalities by NVC qualitative and quantitative assessments may be adopted (9).
The qualitative assessment include the classification of the nailfold microangiopathy into one of the three patterns above reported, and to correctly identify them the following criteria may be used (7–8). “Early” NVC pattern: few (<33%) enlarged/giant capillaries, few (<33%) capillary haemorrhages, relatively well-preserved capillary distribution, absent or mild (<33%) loss of capillaries. “Active” NVC pattern: frequent (>33%) giant capillaries, frequent (>33%) capillary haemorrhages, moderate (<66%) loss of capillaries, moderate (<66%) disorganisation of the capillary architecture, absent or few (<33%) ramified capillaries. “Late” NVC pattern: irregular enlargement of the capillaries, few (<33%) or absent giant capillaries and haemorrhages, severe (>66%) loss of capillaries with avascular areas, disorganisation of the normal capillary array, ramified/bushy capillaries.
The quantitative assessment is performed by adopting a simple rating scale to score each capillary abnormalities (score 0–3) (score 0 = no changes; score 1 = less than 33% of capillary alterations/reduction; score 2 = 33–66% of capillary alterations/reduction; score 3 = more than 67% of capillary alterations/reduction, per linear millimetre. Reduction = capillary number per linear millimetre <9). The mean score value for each capillaroscopic parameter is calculated from the analysis of at least two millimetres in the centre of the nailfold, by evaluating the first row of capillaries in each finger from 2nd to 5th (8). Also the microangiopathy evolution score (MES) may be calculated, by summing the scores of capillary loss, capillary ramifications and capillary disorganization (score 0–9) (8).
Alternative to MES calculation, the simple capillary number per linear millimetre may be adopted to monitor SSc microangiopathy and estimate the risk of digital ulcer appearance (10).
To decrease time of assessment and intra- and inter-operator variability, and increase NVC performance and reliability, automated calculation software are under development to score nailfold capillary number (11–14). Actually, even if enough feasible in counting capillaries in healthy subjects, the performance of these software is strongly reduced when working in the capillary alteration mosaic of scleroderma microangiopathy (e.g. haemorrhages, ramifications, giant capillaries, reduced transparency of nailfold bed).
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Disclosure of Interest None declared