Table 1.

Differences between steatocystoma multiplex and eruptive vellus hair cyst

Features	Steatocystoma multiplex	Eruptive vellus hair cyst
Synonym	Steatocystomatosis, sebocystomatosis, epidermal polycystic disease	Vellus hair cyst
Age	Second and third decade	Common in the second decade
Gender	No gender predilection	No gender predilection
Pathogenesis	Initial sebaceous duct blockage with a keratinous plus result in cyst formation Pluripotent ectodermal cells retain the embryonic capacity to form appendages	Developmental abnormality of vellus hair follicles that predisposes them to occlusion at the infundibulum level Retention of hairs, cystic dilation of the proximal part of the follicle, and secondary atrophy of the hair bulbs
Cytokeratin expression	Express both cytokeratin 10 and 17	Express cytokeratin 10
Clinical features	Asymptomatic, multiple, round, firm, skin-colored to yellowish, mobile cystic papules and nodules of size 2 mm to 20 mm	Asymptomatic, small follicular red or brown papules of 1 to 2 mm diameter
Surface changes	Often normal with no surface changes Can suppurate	Some can have central puncta, umbilicated, or a hyperkeratotic crust
Site	Common in the trunk, neck, scalp, axilla, proximal extremities, inguinal region	Chest and axilla
Course	No spontaneous resolution	Spontaneous resolution in 25% of lesions
Dermoscopy	Yellowish structureless areas with diffuse margins	Erythematous maroon halo with occasional irregular radiating capillaries at the periphery Vellus hairs open into the dermis
Histopathology	Well-encapsulated cysts whose walls contain several layers of intricately folded epithelial cells and flattened sebaceous gland globules within or in close proximity to cyst wall A thick eosinophilic cuticle protrudes into the lumen	Squamous epithelium-lined cysts in the mid-dermis containing vellus hair and keratin debris