An asymptomatic, permanent, benign, linear, flesh-colored, fine papular eruption has been observed after puberty principally involving institutionalized Negroes. Eighty patients showed forehead involvement, but some had similar lesions on the neck, nose and temporal areas.
Histopathologic and histochemical tissue studies from nine patients showed similar changes. Epidermal features mimic melanocytic epithelial nevi with Langerhans' cells, incontinence of pigment, and a proliferation of dermal nerves, many of which contain melanin. Striking are pilosebaceous follicles showing large sebaceous glands, lanugotype hairs, and perifollicular fibrosis. The dermis exhibits subepidermal fibrosis, focal capillary-endothelial hyperplasia, collagen and elastin proliferation, and an increase in acid mucosaccharides associated with the stroma, pilosebaceous follicles, and eccrine sweat glands.
Correlation of features indicates the disease represents an acquired ectodermal-mesodermal hamartoma. Etiological factors have not been detected other than mental retardation in all patients.
Butterworth T, Graham JH. Linear Papular Ectodermal-Mesodermal Hamartoma (Hamartoma Moniliformis). Arch Dermatol. 1970;101(2):191-205. doi:10.1001/archderm.1970.04000020061010