Case Report
A two-year-old boy with a fair complexion presented with multiple, light brown macules, evenly distributed on the cheeks and the forehead (Fig. 1a-b). The family history was negative for skin diseases. According to the mother, small macular lesions had appeared at the age of 9 months on the left temple without any preceding inflammation. Subsequently, new lesions developed, particularly after the summer. Differential diagnoses included juvenile warts, freckles and urticaria pigmentosa. The Darier sign was negative. Since the lesions were restricted to the face and increased after environmental sun exposure also a diagnosis of xeroderma pigmentosum (XP) was considered. However, genetic testing for a mutation in the ERCC 3 gene was negative. Five months later the number of lesions had increased and the macules had evolved into monomorphic flat reddish brown papules. (Fig. 2a-b) The clinical presentation now indicated a diagnosis of benign cephalic histiocytosis (BCH). Confirmation of the clinical diagnosis by histopathology was not possible, as the mother did not consent to a biopsy from the face, where at that time the lesions were exclusively located. A complete blood count, comprehensive blood chemistry and an abdominal ultrasound were all unrevealing. In light of the benign nature of BCH and its propensity for spontaneous resolution a watchful waiting approach was chosen.
At follow-up examinations 9 and 16 months later a few new lesions had developed in the pelvic area and on the dorsal forearms and none of the pre-existing lesions had regressed. Two and a half year later part of the extracephalic lesions had completely disappeared and the lesions on the head were fading (Fig. 3a-b).