1. Nail Studies Center, Instituto de Dermatologia Professor Rubem David Azulay Hospital Geral da Santa Casa da Misericórdia do Rio de Janeiro Rio de Janeiro RJ Brazil
2. Nail Diseases Outpatient Clinic, Department of Dermatology, Hospital Universitário Pedro Ernesto Universidade do Estado do Rio de Janeiro (HUPE‐UERJ) Rio de Janeiro RJ Brazil
3. Private Dermatology Practice Bellinzona Switzerland
4. Department of Specialised Experimental and Diagnostic Medicine, Dermatology, Alma Mater Studiorum Universita` di Bologna Bologna Italy
5. Department of Dermatology Inselspital, University of Bern Bern Switzerland
6. Dermatology Practice Dermaticum Freiburg Germany
7. Centro Dermatología Epidermis Inst CUF, Senhora da Hora Grande Porto Portugal
8. Department of Dermatology University Hospital Ghent Belgium