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A 31-year-old woman of Middle Eastern descent is referred for evaluation of a rash affecting her upper back and lower legs, which she describes as incessant and severe. She was diagnosed with eczema approximately 18 months ago and has received treatment with both topical steroids and tacrolimus, neither of which improved the clinical appearance or itching. She has a history of hay fever and is currently on no medications. Physical examination reveals well-demarcated hyperpigmented macules.
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Macular amyloidosis is the result of extracellular amyloid deposition within the skin.1 Severe pruritus is often the presenting symptom followed by the development of hyperpigmented macules. The macules tend to be symmetrical in distribution and are often brown or blue-grey in color. Macular amyloidosis is more common in women and among persons of Asian, Middle Eastern, and South American descent.2 The etiology of macular amyloidosis is unclear; genetic and environmental factors may play a role in disease development and progression.
A common dermoscopic feature of macular amyloidosis is a central hub surrounded by pigmented projections (“hub and spoke” pattern).3 Definitive diagnosis is made by skin biopsy, which reveals amyloid deposits in the dermal papillae. Congo red stain is the gold standard for detecting amyloid in tissue.4
Treatment of macular amyloidosis is primarily aimed at the relief of itching.4 Patients should be educated on avoidance of aggravating environmental factors such as repeated friction, rubbing, and/or scratching of the affected skins. Topical corticosteroids, topical calcineurin inhibitors, and intralesional steroids may prove of benefit. Dermabrasion, transcutaneous electrical nerve stimulation, and phototherapy have been utilized with variable results.5 Some cases have responded to CO2 laser ablation.6
Sara Mahmood, DPM, is a podiatrist who completed a joint dermatology/podiatry fellowship and is on staff at the DermDox Dermatology Centers in Pennsylvania. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Brownstein MH, Hashimoto K. Macular amyloidosis. Arch Dermatol. 1972;106(1):50-57.
2. Eswaramoorthy V, Kaur I, Das A, Kumar B. Macular amyloidosis: etiological factors. J Dermatol. 1999;26(5):305-310. doi:10.1111/j.1346-8138.1999.tb03476.x.
3. Sonthalia S, Agrawal M, Sehgal VN. Dermoscopy of macular amyloidosis. Indian Dermatol Online J. 2020;12(1):203-205.
4. Weidner T, Illing T, Elsner P. Primary localized cutaneous amyloidosis: a systematic treatment review. Am J Clin Dermatol. 2017;18(5):629-642. doi:10.1007/s40257-017-0278-9
5. Kaltoft B, Schmidt G, Lauritzen AF, Gimsing P. Primary localised cutaneous amyloidosis–a systematic review. Dan Med J. 2013;60(11):A4727.
6. Radmanesh M, Ghanatir F, Radmanesh R. Comparing the efficacy of pulsed dye laser, Q-Switched Nd-YAG, CO2, and combined CO2 and Q-Switched Nd-YAG lasers for the treatment of cutaneous macular amyloidosis. J Dermatolog Treat. 2021;32(2):258-260. doi:10.1080/09546634.2019.1654071
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