[Ultrasound-guided fine needle aspiration cytology (FNAC) of unclear lesions in melanoma patients]. 
Fine needle aspiration cytology (FNAC) is widely used in oncology to obtain the diagnosis of unclear tumours in cancer patients.  However, because the method is established only in few melanoma centers, we performed this study to evaluate ultrasound guided FNAC in routine follow-up of melanoma patients.  Unclear tumours recognised during routine follow-up of melanoma patients underwent ultrasound guided fine needle aspiration with cytological examination.  The results were then compared to subsequent histopathology or future clinical outcome.  275 unclear tumours received ultrasound guided fine needle aspiration with cytological examination.  Sensitivity showed to be 95.6% [95% CI: 91.5-98.1], specificity was 100% [95% CI: 96.2-100.0].  The positive predictive value was 100.0% [95% CI: 97.9-100.0], the negative predictive value 92.2% [95% CI: 85.1%-96.9%].  In 89 cases lesions turned out to be cytologically benign thus diagnosis avoiding surgery.  In lesions with diameters up to 10 mm sensitivity and specificity were 91.4% and 100.0%, respectively.  Ultrasound guided FNAC proved to be a minimal invasive procedure in the diagnosis of unclear tumours in the follow-up of melanoma patients.  It allows definite diagnosis and avoids unnecessary diagnostic surgery.