Polycystic Lipomembranous Osteodysplasia with Sclerosing Leukoencephalopathy (PLOSL): a new report of an Italian woman and review of the literature.

We report the clinical case of a 43year old Italian woman and her family with Polycystic Lipomembranous Osteodysplasia with Sclerosing Leukoencephalopathy (PLOSL), also known as Nasu-Hakola disease. PLOSL is a unique disease clinically characterized by a progressive presenile frontal-lobe dementia and multiple cystic bone lesions, typically leading to fractures of the limbs in the third decade of life. This rare recessively inherited disease is caused by mutations in one of two genes encoding different subunits of a receptor signalling complex, TYROBP and TREM2. In the present case fractures after microtrauma were not diagnosed, despite a radiological demonstration of the characteristic bone lesions in PLOSL. Further investigation led to the same diagnosis in her brother, with similar clinical presentation and the same mutation. Therefore a diagnosis of PLOSL should be considered in cases of presenile frontal-lobe dementia, even if the hallmark of pathological fractures is absent.