Histiocytoses are rare diseases caused by the proliferation of histiocytes. The pathogenesis remains unknown and the highest incidence occurs in pediatric patients. The clinical presentations can be varied, in multiple organs and systems, and the skin lesions are not always present. Evolution is unpredictable and treatment depends on the extent and severity of the disease. It is described the case of a patient with various neurological symptoms, extensively investigated, who had its was diagnosed with histiocytosis from a single skin lesion. This report highlights the importance of Dermatology in assisting the investigation of difficult cases in medical practice.

Alzheimer´s disease (AD) and dementia have a probably multifactorial pathogenesis and, accordingly to several studies, human herpes simplex virus type 1 (HSV-1) infection may be related. The purpose of this review is to assess the updated clinical evidence towards the association between herpes infection and AD. We performed a PubMed/MEDLINE database research and included in this review randomized clinical trials on the subject of antivirals effectiveness and AD, and observational case-control studies and observational cohort studies regarding AD diagnosis (using clinical and/or histological methods) and HSV-1 detection (using molecular biology or immunohistochemical techniques). A total of 23 case-control and 3 cohort studies met the predetermined inclusion criteria. The results showed that AD was associated with HSV-1 in 22 of the 26 included studies, with most of them confirming that herpes infection is more prevalent in AD patients, when compared to control patients. A possible link between HSV-1 and AD was discussed and many different interpretations and hypothesis were considered. Evidence from observational studies suggests a possible relationship between the two conditions, but the role of HSV-1 infection in the pathogenesis of AD is not completely understood yet. Well-designed and large clinical trials are necessary to endorse this hypothesis and to consider the use of antiviral drugs as a potential alternative for prevention or reduction in the progression rate of AD in the future.

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