Reticulohistiocytoma is a cutaneous condition characterized by a solitary, firm, dermal

Dermis

The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...

 skin lesion of less than 1cm in diameter. It usually occurs in young adults or middle aged people, most commonly in females. Affected regions include the head and neck region and the upper part of the trunk. It may coexist with certain neoplasms or vasculitis

Vasculitis

Vasculitis refers to a heterogeneous group of disorders that are characterized by inflammatory destruction of blood vessels. Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis...

, and in 30 percent of patients with xanthelasma

Xanthelasma

Xanthelasma is a sharply demarcated yellowish deposit of cholesterol underneath the skin, usually on or around the eyelids. Although not harmful or painful, these minor growths may be disfiguring and can be removed...

.