Correlation of systemic involvement and presence of pathological skin calcification assessed by ex vivo nonlinear microscopy in Pseudoxanthoma elasticum.

"Declarations Conflict of interestThe authors declare that they have no conflict of interest. Ethics approvalAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Ethics Committee in Budapest, Hungary (SE RKEB no. 193–2/2017). Informed consentInformed consent was obtained from all individual participants included in the study. Conflict of interest The authors declare that they have no conflict of interest."

"Funding Open access funding provided by Semmelweis University. This work was supported by the National Research, Development and Innovation Office of Hungary – NKFIH [FK_131916, 2019 (Semmelweis University, MM)], EFOP-3.6.3-VEKOP-16–2017-00009 (SP, DP, KF), COST action CA16115 EuroSoftCalcNet, the New National Excellence Program of the Ministry For Innovation and Technology [ÚNKP-20–4-II-SE-7, ÚNKP-21–4-II-SE-10 (NK) and ÚNKP-20–3-I-SE-24 (SP)] and the Development of scientific workshops of medical, health sciences and pharmaceutical educations of the European Structural and Investment Funds [EFOP-3.6.3-VEKOP-16–2017-00009 (LF)] in the collection, analysis and interpretation of data. The Department of Dermatology, Venereology and Dermatooncology, Semmelweis University is a Reference Centre of the ERN-Skin: European Reference Network on Rare and Undiagnosed Skin Disorders."