Primary Cutaneous Amyloidosis

Primary cutaneous amyloidosis is a form of amyloidosis, a group of conditions in which an abnormal protein (called amyloid) builds up in various organs and tissues throughout the body. In primary cutaneous amyloidosis, specifically, this protein accumulates in the skin. There are three main forms of primary cutaneous amyloidosis:

• Lichen amyloidosis - multiple itchy, raised spots which are scaly and red/brown in color. This rash generally affects the shins, thighs, feet and forearms.
• Macular amyloidosis - mild to severely itchy, flat, dusky-brown or greyish colored spots that may come together to form patches of darkened skin. This rash generally appears on the upper back between the shoulder blades, the chest and less commonly, the arms.
• Nodular amyloidosis - asymptomatic firm bumps that may be pinkish-brown to red in color. This rash may occur on the trunk, limbs, face, and/or genitals.

The exact underlying cause of primary cutaneous amyloidosis is poorly understood. It is sometimes associated with other conditions such as atopic dermatitis, sarcoidosis, and psoriasis. Although most cases occur sporadically in people with no family history of the condition, there are rare familial forms caused by changes (mutations) in the OSMR or IL31RA gene. Treatment is based on the signs and symptoms present in each person and may include surgery to remove amyloid deposits and/or certain medications to relieve itching.