Microvascular damage is one of the most important clinical feature of systemic sclerosis (SSc), and nailfold videocapillaroscopy (NVC) is the recognized tool to study morphological capillary abnormalities. NVC may detect the “Early” pattern of microangiopathy, follow the evolution of the microangiopathy, and it has been also proposed as possible biomarker in SSc, correlating the vascular damage degree with the internal organ involvement [1,2].
Pathognomonic capillary abnormalities are usually present in SSc patients, characterizing the scleroderma-pattern of microangiopathy [2–4]. Among these, microhaemorrhages, giant capillaries (dilation of both capillary branches >50 microns), reduction of capillary number, ramified (neoangiogenic) capillaries and disorganization of the vascular array are the major capillary abnormalities. However, these abnormalities are not present all together at the same time, and three different patterns of nailfold microvascular damage (“Early”, “Active” and “Late” scleroderma-patterns), have been proposed and validated in scleroderma patients [3–6]. These patterns characterize three different consecutive phases of the SSc microangiopathy . Even if the factors influencing the time of evolution of the microangiopathy from the “Early” to the “Late” stage have not yet been determined, in some patients capillary abnormalities 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 .
The earliest stage of microangiopathy in SSc is characterized by the appearance of homogeneously enlarged capillaries (giant capillaries), which are the pathognomonic feature of the “Early” scleroderma-pattern; microhaemorrhages arise as a consequence of the damaged microvessel walls and, together with the presence of giant capillaries, are the recognized markers for the diagnosis of secondary Raynaud's phenomenon. Subsequently, as the microangiopathy progresses, normal-shaped capillaries decrease, with all capillaries becoming irregularly enlarged or “giant”; microhaemorrhages may occur concomitantly (as a consequence of giant capillary collapse), and the loss of capillary number becomes evident. These abnormalities characterize the “Active” scleroderma-pattern. In the advanced stage of the microangiopathy, both microhaemorrhages and giant capillaries disappear, and only irregularly enlarged capillaries may be still present; the dramatic reduction of capillary number promotes large avascular (ischemic) areas, and a compensatory (although disturbed) neoangiogenesis with ramified capillaries induces a microvascular array disorganization (“Late” scleroderma-pattern) [2,7,8]. This late phase of the microangiopathy was found to correlate with greater organ involvement and disease severity [1,7,9].
To correctly classify the three qualitative patterns of nailfold microangiopathy by NVC, 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.
Automated calculation software to score nailfold microangiopathy is under development, in order to increase NVC performance and reduce interoperator variability.
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Disclosure of Interest None declared