Common mistakes in capillaroscopy

Nail fold capillaroscopy (NFC) is a non-invasive examination and the "gold standard" in rheumatology practice to evaluate the microcirculation and distinguish primary from secondary Raynaud's phenomenon (RP). Alternatives to videocapillaroscopy are USB microscopy, dermatoscopy and ophthalmoscopy. Before the capillaroscopy examination, a detailed general history (including concomitant diseases) and occupational history (including a history of recent trauma to the fingers or onychophagia), a history regarding the patient's hobbies, practicing sports and physical activity, history of taking medications (beta-blockers, vasodilators, anticoagulants, antihypertensives), as well as the use of other vasoactive substances (tobacco, caffeine, cannabis, cocaine, amphetamines) should be taken. A detailed history regarding discoloration of the fingers is necessary to confirm the diagnosis of Raynaud's phenomenon (RP). Capillaroscopic examination should be carried out under certain conditions (not during an attack of RP, after acclimatization, in a certain position of the patient, without consumption of coffee and smoking before the examination, without manicure procedures in the last 15-30 days, examination of all 8 fingers, excluding those with recent trauma and/or infection). Correctly following all these steps will avoid technical errors that can change the interpretation of the result. It is necessary for the examiner to have a good knowledge of the normal capillaroscopic pattern, the variations of the norm in adults, the differences that might be found between children and adults, as well as the different pathological findings and specific patterns ("scleroderma" and "scleroderma-like" type) in diseases occurring with secondary RP. While in rheumatology practice there are defined criteria for "scleroderma" and "scleroderma-like" capillaroscopic finding, the changes in some paraneoplastic, socially significant (AH and DM), occupational (VD) and infectious diseases (Covid-19) occurring with microangiopathy, which can lead to misinterpretation of the finding. The “scleroderma-like” pattern also differs in different rheumatic diseases and the findings can also be misleading. The results of the study must be carefully interpreted with a view to the correct assessment of the patients' condition.