Todd T., a dermatology resident at Still OPTI, shares how he used VisualDx’s image collection to narrow diagnosis:
“A 60-year-old woman presented to the dermatology clinic with a chief complaint of a long-standing itchy rash on her upper back. Based on the clinical presentation and location I suspected notalgia paresthetica, however once I examined the rash I found that the area was darker and thicker than what I suspected. I remembered that notalgia paresthetica can turn into amyloidosis after a long period of time, however I couldn’t recall what form of amyloidosis it turned into.
I opened VisualDx and searched Kodachromes of the different forms of amyloidosis and the patient’s rash was nearly identical to macular amyloidosis. After reading more about macular amyloidosis on VisualDx I was confident in the diagnosis and prescribed my treatment plan. Thank you VisualDx!”
What is macular amyloidosis?
Macular amyloidosis (MA) is a form of primary cutaneous amyloidosis (a category which also includes lichen and nodular amyloidosis, poikiloderma-like cutaneous amyloidosis, primary cutaneous amyloidosis of the auricular concha, and the exceedingly rare entity of amyloidosis cutis dyschromica). In MA, a proteinaceous material, amyloid, which is derived from keratinocytes, is deposited in the superficial dermis without involvement of other tissue.
While the cause of MA is incompletely understood, it is associated with, and probably caused by, friction and scratching with fingernails or implements such as towels or brushes.
What should we be aware of when making a diagnosis?
Clinically, MA manifests as hyperpigmentation. The most common locations are the upper back and extensor upper extremities. A rippled pattern is sometimes seen. MA and lichen amyloidosis (LA) are believed to exist on a spectrum and are mainly differentiated by the nature of the primary lesion (macules and patches in MA and thin plaques in LA) and histopathologic findings. Some patients also display features of both MA and LA, which is termed “biphasic amyloidosis.”
How can we treat this?
- High-potency topical corticosteroids (class 1-2).
- Superpotent corticosteroids should not be used on intertriginous areas due to skin atrophy and striae formation.
- Other pharmacologic options include topical calcineurin inhibitors, intralesional corticosteroids, systemic retinoids, cyclophosphamide, and cyclosporine.
- UVB phototherapy
- Dermabrasion – May not eliminate underlying itch.
- Carbon dioxide (CO2) laser – May not eliminate underlying itch. Patients with darker skin phototypes are at a greater risk for developing postinflammatory hyperpigmentation after treatment with ablative lasers.