Nailfold dermoscopy may be screening tool to assess aHUS disease activity

Capillary abnormalities in the nail fold seen in patients with technique

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by Andrea Lobo |

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Reduced capillary density and capillary abnormalities were identified in people with atypical hemolytic uremic syndrome (aHUS) using a nailfold dermoscopy, a study in Turkey reports.

Nailfold dermoscopy is a noninvasive technique that lets doctors evaluate the small blood vessels (capillaries) in the nail fold. These observations suggest the technique could be a screening tool to assess disease activity in people with aHUS, the researchers said in “The nailfold dermoscopy findings of patients with atypical haemolytic uremic syndrome,” which was published in Microvascular Research.

aHUS is a rare disease caused by the abnormal activity of the complement cascade, a part of the immune system. Complement overactivation leads to increased inflammation and blood clotting in small blood vessels, particularly in the kidneys, which in turn can cause organ damage.

As complement overactivation persists, so does inflammation and blood vessel and organ damage. Therefore, simple and noninvasive tests are needed to evaluate disease activity by assessing changes in the structure of small blood vessels.

Nailfold capillaroscopy is a method that lets doctors examine the capillaries in the nail fold. High magnification nailfold video capillaroscopy is considered the gold standard. The technique requires special equipment and is not easily accessible, however.

The study evaluated disease activity and small blood vessel changes in aHUS patients using a dermoscope — an inexpensive and portable device that can visualize nailfold capillaries — connected to an iPhone.

Seven patients (four females, three males) and seven healthy children were included. Patients had a median age of 99.53 months (around 8 years) and had the disease for a mean of 48 months (around four years). Control group participants had a median age of around 10.

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Nail fold abnormalities in aHUS

At the dermoscopy, all the patients were in remission under Soliris (eculizumab), an approved aHUS therapy that blocks complement activation.

Every participant’s fingers were examined and particular attention was paid to the fourth finger of the nondominant hand, which has the best visualization area. Data were recorded for the area of focus (the most prominent dermoscopic area) and the wide view.

There was a significant reduction in mean capillary density between patients and controls, both in the area of focus (2.86 vs. 7.57) and wide view (4.29 vs. 7.14).

Enlarged capillaries were detected in three patients, abnormal capillary shapes were seen in three patients, and disorganized capillary architecture was observed in two. No capillary enlargement or abnormal shapes were detected in any control group children.

Capillary abnormalities were detected in the four patients with mutations in the CFH gene. Mutations in this gene have been implicated in aHUS and can trigger small blood vessel damage, according to other studies.

Capillary bleeding was not observed in any participant.

“Although our sample size was small, and all our cases were in remission, nailfold capillary abnormalities were observed significantly higher in the aHUS group compared to the control group. This study suggests that dermoscopy can be used as a screening tool and [nailfold video capillaroscopy] should be explored in future research in aHUS patients,” the researchers wrote.