By Gary M. White, MD
Macular Amyloidosis (MA) is caused by the deposition of an amorphous hyaline protein, restricted to the papillary dermis, without any systemic manifestations. For a related condition, see frictional melanosis.
Dark brown patches which may have a reticulated or rippled pattern are typical. The back and shins are common sites, but widespread lesions may occur. Causes for pruritus should be sought, e.g., xerosis.
The most valuable intervention is to convince the patient not to scratch! Spend a few moments asking about how they shower and how they care for their skin. Many patients scrub in the shower and/or use a brush to scrub the back. This they must stop!! Potent topical steroids used over several weeks may help flatten out the lesions and decrease pruritus. However, no matter how potent the steroid, the lesions will persist if the patient persists in scratching.
If any pruritus is from dry skin, then moisturizing immediately after the shower with an emolliating cream or ointment may help. No lotions please. UVB may be tried, here along with tacrolimus [J Pak Med Assoc. 2014 May;64(5):579-82]. Acitretin has been used. To reduce pigmentation, various lasers have shown significant benefit [Lasers Surg Med. 2015 Jul;47(5):388-95], e.g. the Q-switched Nd:YAG laser.
Two cases of macular amyloidosis of notalgia paresthetica. In the past, this was called "puzzling posterior pigmented pruritic patches". The patient's scratching causes the pigmentation.
The linear, rippled pattern of macular amyloidosis.
Macular amyloidosis close up showing an irregular pattern.
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