Juvenile xanthogranuloma and nevus anemicus in the diagnosis of neurofibromatosis type 1.

IMPORTANCE: The diagnosis of neurofibromatosis type 1 (NF1) is based on 7 clinical criteria. However, they are of limited value before the age of 2 years. Juvenile xanthogranuloma (JXG) and nevus anemicus (NA) are commonly observed in children with NF1 and may be useful diagnostic clues.

OBJECTIVES: To evaluate the frequency of JXG and NA, to describe their clinical features, and to determine their diagnostic value in patients with NF1.

DESIGN, SETTING, AND PARTICIPANTS: Retrospective medical record review of outpatients seen between January 1, 2005, and December 31, 2011. University hospital dermatology department affiliated with the French NF1 referral center network. Patients with NF1 diagnosed by at least 2 National Institutes of Health criteria and examined at our department.

MAIN OUTCOMES AND MEASURES: Percentage of patients with NF1 who had JXG or NA categorized into 4 age groups.

RESULTS: Among 72 patients with NF1 (median age, 15.4 years), 23 had JXG (10%) or NA (25%). Both lesions were more frequent (55%) in those younger than 2 years (JXG, 30%; NA, 35%). Most JXG lesions were multiple and resolved spontaneously. Cephalic and genital involvement was frequent. No patient with JXG developed chronic myelomonocytic leukemia. Nevus anemicus was present on the neck and upper chest in 72% of cases. Among 10 patients (14%) who had only 1 diagnostic criterion at first visit, including 9 younger than 2 years, JXG or NA was present in 8 (80%).

CONCLUSIONS AND RELEVANCE: We found a high frequency of JXG and NA in patients with NF1, especially in children younger than 2 years with fewer than 2 diagnostic criteria. Hence, JXG and NA appear helpful in improving early diagnosis of NF1 in young children and infants.