A skin biopsy is typically performed for definitive diagnosis. The histopathologic hallmarks of EAH include the presence of an increased number of<unk>  glands in the mid- and lower dermis along with ectatic or collapsed vessels that are seen in close approximation to the hyperplastic<unk>  units. The overlying epidermis may be normal or may show acanthosis or papillomatosis. A recent report of EAH located on the neck described dermatoscopic features of multiple yellow, confluent nodules in a popcorn-like shape over a background of erythema and linear, arborizing vessels. Dermoscopy is minimally invasive, inexpensive and may provide another diagnostic modality in the differentiation of EAH from other diagnoses, but has yet to be validated. Differential Diagnosis Vascular malformations: *<unk>  nevus – Characterized histopathologically by an increase in<unk>  structures but not capillaries. Clinical hallmark is hyperhidrosis in most cases. * Tufted angioma * Smooth muscle hamartoma – These flesh-colored plaques may have associated hypertrichosis. A "chicken-skin" appearance (pseudo-Darier sign) may be seen with piloerection. * Glomus tumor – Painful bluish papules, single or multiple, are encountered, mainly on acral areas of the body. * Blue rubber bleb nevus * Sudoriparous angioma – Another rare, benign tumor where<unk>  glands of normal number are seen lying close to vascular structures in the dermis; these have a larger caliber than those seen in EAH. Macules: * Nevus flammeus * Angioma serpiginosum * Telangiectasia macularis eruptive perstans
Eccrine angiomatous hamartoma
Folliculosebaceous cystic hamartoma
Basaloid follicular hamartoma
Littoral cell angioma
Neural fibrolipoma
Aggressive angiomyxoma
Malignant acrospiroma
Keratin implantation cyst