Report Onychomadesis after hand-foot-and-mouth disease outbreak in northern Greece: case series and brief review of the literature Zoe Apalla 1 , MD, Eleni Sotiriou 2 , PhD, Olga Pikou 1 , MD, Ioanna Lefaki 1 , PhD, MD, Aimilios Lallas 3 , PhD, Elizabeth Lazaridou 2 , PhD, and Demetris Ioannides 2 , PhD 1 State Clinic, Hospital of Skin and Venereal Diseases, Thessaloniki, Greece, 2 First Department of Dermatology, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece, and 3 Dermatology and Skin Cancer Unit, Arcispedale Santa Maria Nuova IRCCS, Reggio Emilia, Italy Correspondence Zoe Apalla, MD 124 Delfon Street Thessaloniki 54643 Greece E-mail: zoimd@yahoo.gr Funding sources: None. Conflicts of interest: None. doi: 10.1111/ijd.12592 Abstract Background Nail abnormalities in childhood are generally uncommon. Recently, onychomadesis was described as a late complication of hand-foot-and-mouth disease (HFMD). Onychomadesis outbreaks following HFMD have been reported in many countries worldwide. Aim To present a case series of onychomadesis in children, following HFMD outbreak in Northern Greece, and review literature data. Methods Children with evident onychomadesis attending the outpatient clinic between November 2012 and January 2013 were included in the study. A questionnaire including demographic personal and family history information of the children was completed by the parents. Patients were clinically examined, and their pediatric and dermatological records were studied to confirm precedent HFMD. Direct microscopic examination and cultures for fungi were performed. Exposure of participants to coxsackievirus, based on serology testing during infection, was also recorded. Results Sixty-eight children with onychomadesis were included. The mean number of affected nails was 8.82. Fingernails were more often involved. Previous clinical diagnosis of HFMD was confirmed in 67/68 cases. The mean time from HFMD diagnosis to onychomadesis development was 39.6 days (range: 28–56 days, STD: 7.33). Direct microscopic examination, as well as cultures for fungal species, was negative for the whole sample size. All the nail changes were transient with spontaneous regrowth after 1–4 months. Conclusion Our data indicate that onychomadesis outbreak in the region of Thessaloniki during fall–winter 2012–13 was highly related to the outbreak of HFMD. Our study reinforces existing evidence for the association between onychomadesis and HFMD. Introduction Hand, foot, and mouth disease (HFMD) is a relatively common viral infection that predominantly affects young children, usually during the spring and fall months. It is caused by members of the human enterovirus (HEV) genus that belong to the Picornaviridae family. The most often involved serotypes are coxsackievirus A16 (CVA16) and enterovirus 71 (EV71), which both belong to the HEV-A species. However, other HEV-A serotypes, as well as some HEV-B, have also been associated with flares of the disease. 1 Although in the majority of cases flares are sporadic, epidemics may also occur. In childhood, nail abnormalities are generally rare and can manifest either in the context of inherited diseases, or because of systemic illnesses, trauma, or drug uptake. Additionally, many cases are considered idiopathic. Even though nail matrix arrest had been previously related to viral infections, only recently onychomadesis was described as a late complication of HFMD. 2,3 Since then, onychomadesis outbreaks following HFMD have been reported in many countries worldwide. 4–12 The aim of the current study is to present a case series of 68 children with evident nail changes following an HFMD outbreak in northern Greece and discuss our observations in correlation to the findings of other investigators. Patients and methods We present a case series of 68 children, between 2 and 13 years of age, with evident onychomadesis that attended the outpatient clinic of the Hospital of Skin and Venereal Diseases of Thessaloniki in Greece between November 2012 and January 2013. Parents of all patients provided written informed con- sent before any study-related procedure. They were also given a questionnaire to complete at the time of the first ª 2015 The International Society of Dermatology International Journal of Dermatology 2015 1