APS and vasculitis: what capillaroscopy can add and what it cannot

APS: what is established

The capillaroscopy literature on APS is scarce, fragmented, and based on small cohorts. This limitation shapes all subsequent clinical interpretation [1, 2, 3, 4, 5, 6, 7].

A large retrospective study of connective tissue diseases with Raynaud's phenomenon from a European Alliance of Associations for Rheumatology (EULAR) center showed that most patients with APS had normal or nonspecific capillaroscopy, with only a minority showing a pattern resembling scleroderma [2]. Ferrari et al reached a similar conclusion: both patients with APS and antiphospholipid antibody carriers without APS mainly had nonspecific abnormalities; the main difference was a greater frequency of hemorrhages in APS than in asymptomatic carriers [3].

The classical study by Vaz et al, focused on primary APS, added another qualification. It found morphological abnormalities in 77.8% of patients, but no clear functional reduction in density or conclusive disturbance of resting flow [4]. In practical terms, APS may produce visible microvascular injury, but this does not have a unique morphology or form an easily recognizable pattern.

Hemorrhages and interpretation pitfalls

Symmetrical hemorrhages are the most frequently cited abnormality in APS, but also the easiest to misinterpret when context is overlooked [3, 4, 5, 6, 7].

Sulli et al noted years ago that capillaroscopic abnormalities could be more frequent in patients with antiphospholipid antibodies [5]. Aslanidis et al went further, linking capillaroscopic hemorrhages with thrombosis and the antiphospholipid immunological profile in patients at high vascular risk [7]. However, these observations came from populations selected for high clinical suspicion and do not support a broadly applicable screening strategy.

Ferrari et al introduced a crucial methodological caution: when patients with APS are compared both with antibody carriers and with controls anticoagulated for non-immunological indications, the apparent discriminatory value of hemorrhages diminishes [3]. Before attributing hemorrhage to APS, consider two potential sources of error: local trauma, including cosmetic manipulation, and anticoagulation. Without this context, the finding loses much of its value.

Can capillaroscopy diagnose APS?

No, if diagnosis means replacing clinical and laboratory criteria. It may contribute in selected settings, but its performance is modest [1, 2, 3, 4, 5, 6, 7].

Pyrpasopoulou et al proposed capillaroscopy as a screening test for clinical APS, and Aslanidis et al incorporated it into a strategy for patients with signs of vasculopathy [6, 7]. These studies do not establish a sufficiently robust pattern to support a general recommendation. The most cautious current approach is that, in a patient with livedo, Raynaud's phenomenon, thrombosis, or a compatible obstetric history, symmetrical hemorrhages or marked microangiopathy may strengthen suspicion and prompt completion of the workup. They cannot establish the diagnosis without persistent serological positivity and the relevant criteria.

Conversely, normal capillaroscopy cannot exclude APS. The literature agrees that a substantial proportion of patients with confirmed APS have normal or only nonspecific examinations [2, 3]. This is crucial to avoid using the technique as a rule-out test.

Vasculitis: emerging evidence

Unlike APS research, the vasculitis literature focuses less on a typical finding and more on whether capillaroscopy can reflect microvascular inflammatory activity. This is an appealing but still preliminary hypothesis [8, 9, 10, 11].

Keret et al compared active systemic vasculitis, vasculitis in remission, and healthy controls, finding more neoangiogenesis and capillary loss in active disease. They also described two underexplored signs, rolling and peri-capillary stippling, potentially related to slowing of flow and capillary leakage [8]. These findings come from a small, heterogeneous cohort and generate hypotheses rather than establish new diagnostic terminology.

The strongest evidence so far comes from AAV. Among 51 patients, Matsuda et al found a microangiopathy pattern in 70.6%, a scleroderma pattern in 7.8%, and correlations between capillaroscopic scores and the severity of skin, lung, and kidney involvement. Hemorrhages also decreased after three months of immunosuppression [9]. Capillaroscopy could therefore serve as a complementary marker of activity and response in AAV, although multicenter validation is still needed.

More recently, Bhandare et al found that avascular areas, dropouts, receding capillaries, and disorganization were more frequent in cutaneous vasculitis than in controls, with more findings in patients with systemic involvement or ulcerated lesions [11]. This does not establish a specific pattern, but suggests the technique may detect microvascular burden in a subset of patients.

A. Capillary dilation · left middle finger (L3B)

B. Hemorrhagic spots · right little finger (R5D)

AAV, Behçet's disease, and cutaneous vasculitis

Capillaroscopy does not have the same value in every vasculitis. It is useful to distinguish conditions with reproducible signals from those supported only by anecdotal findings [8, 9, 10, 11].

In AAV, the combination of hemorrhages, capillary loss, neoangiogenesis, and tortuosity appears consistent and is also associated with organ involvement [9]. In Behçet's disease, the Mercadé-Torras cohort found qualitative abnormalities, mainly tortuous or abnormal capillaries, in 47.7% of patients. Having two or more abnormalities was associated with vascular disease, particularly superficial thrombophlebitis [10]. These findings suggest possible value in identifying vascular phenotypes, but do not establish a specific Behçet's pattern.

In cutaneous vasculitis, the evidence is even more exploratory. A recent study using a handheld dermatoscope found more disorganization, dropouts, avascular areas, and receding capillaries in patients with systemic involvement, comorbidity, or ulcerated lesions [11]. This is clinically interesting because the technique is inexpensive and accessible, but the sample size and methods do not yet support a formal recommendation.

Insufficient evidence / not found. There is insufficient published or practical support for using capillaroscopy as a universal screening tool for systemic vasculitis or as a replacement for biopsy, vascular imaging, or serological markers.

Practical reporting

In APS and vasculitis, a useful report should be even more cautious than in SLE. Overvaluing findings is a greater risk than underestimating them in these settings [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11].

• Describe whether hemorrhages are symmetrical, focal, extensive, or compatible with trauma.
• If the patient receives anticoagulation, explicitly include this in the interpretation.
• In vasculitis, prioritize domains such as capillary loss, neoangiogenesis, tortuosity, and disorganization before assigning a pattern.
• Avoid terms such as “capillaroscopy diagnostic of APS” or “vasculitis confirmed by the image.”
• Use conditional conclusions: “findings compatible with nonspecific microangiopathy” or “abnormalities that may accompany vascular activity.”

Short cases

Case 1. Anticoagulated APS with hemorrhages

A woman with thrombotic APS receiving warfarin has symmetrical nailfold hemorrhages. The finding is compatible with the syndrome and may support the vascular context, but must be interpreted alongside anticoagulant treatment. It does not change the diagnosis or treatment strategy on its own [3, 4, 5, 6, 7].

Case 2. AAV with lung and kidney involvement

A patient with active AAV has capillary loss, hemorrhages, and neoangiogenesis. Capillaroscopy adds a signal of microvascular activity consistent with the systemic picture and may help document response after immunosuppression. Treatment decisions still depend on the Birmingham Vasculitis Activity Score (BVAS), kidney function, imaging, and histology when appropriate [8, 9].

FAQ

Glossary

APS

Antiphospholipid syndrome, a thromboinflammatory condition defined by clinical criteria and persistently positive serological findings.

Symmetrical hemorrhages

Repeated capillary extravasations across several fingers in a relatively regular distribution; suggestive in APS, but nonspecific.

Rolling

An exploratory term proposed in systemic vasculitis for visible slowing of capillary flow.

Peri-capillary stippling

Punctate pericapillary deposits described in a small cohort with active vasculitis, still lacking broad external validation.

AAV

ANCA-associated vasculitis, a group of small-vessel vasculitides in which capillaroscopy has shown greater clinical utility outside the scleroderma spectrum.