Routine hematoxylin-eosin staining of the skin biopsy specimen showed a collection of histiocytic cells in the upper and middle dermis forming a dome-shaped nodule. The histiocytic cells contained pink cytoplasm with oval to slightly indented nuclei and inconspicuous nucleoli. A few eosinophils, neutrophils, and lymphocytes were present in the lower portion of the lesion. The overlying epidermis was slightly atrophic.
Benign cephalic histiocytosis is a rare, benign, self-healing papular eruption that is classified as a non–X histiocytosis. It was first reported by Gianotti et al1 in 1971. It begins as an eruption of flattop papules, 2 to 3 mm in diameter, ranging from yellowish brown to skin-colored.2 The papules are usually asymptomatic, and the age at onset ranges from 2 to 34 months (average age, 10 months), with a male-female ratio of 2.1:1.0.3
Facial Eruptions in a Child—Diagnosis. Arch Dermatol. 1999;135(10):1267-1272. doi:10.1001/jamadermatol.58605