Nevus Anemicus As an Additional Diagnostic Marker of Neurofibromatosis Type 1 in Childhood.

Diagnosis of neurofibromatosis type 1 (NF1) can be established when at least two out of seven defined clinical findings are present. However, a definite clinical diagnosis may be challenging, especially in young children. Therefore, we tried to identify additional clinical signs suggestive of NF1. We observed that nevi anemici (NA) occur with increased frequency in NF1 patients. To establish NA as an additional diagnostic criterion for NF1 we evaluated their exact frequency in children potentially affected by NF1. During a 6-month period we examined 100 NF1 patients and documented patients' age and sex as well as presence, location, and characteristic features of NA. We were able to show that NA are present in 28% of NF1 patients, which is well above the 5% prevalence of NA in the general population. It is not known why NA appear with increased frequency in NF1. We hypothesize that an imbalance between α- and β-adrenergic receptors, resulting in increased α-adrenergic vasoconstriction might be the underlying cause of NF1-associated NA. Based on our own observations and previously published studies, we propose that NA in children with suspected NF1 might facilitate definite diagnosis and improve clinical management.