Macular Amyloidosis Workup

Updated: Feb 01, 2019
  • Author: Sultan Al-Khenaizan, MBBS, FRCPC; Chief Editor: William D James, MD  more...
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Workup

Approach Considerations

Macular amyloidoisis is usually diagnosed clinically. The most common dermoscopic finding of macular amyloidosis is a central hub of either white or brown surrounded by various configurations of brownish pigmentation, including fine radiating streaks, dots, leaf-like projections, and bulbous projections. [4]  For cases with atypical presentations, skin biopsy may be necessary.

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Histologic Findings

Many stains can demonstrate amyloid deposits in the skin. The best known is the Congo red stain, which under polarizing light gives apple-green birefringence. Other stains include periodic acid-Schiff (PAS); methyl violet; crystal violet; various cotton dyes (eg, pagoda red, Sirius red); and the fluorescent dyes thioflavin-T and Phorwhite BBU.

In macular amyloidosis, the amyloid deposits are usually found within the dermal papillae. The amyloid deposits are usually globular, resembling colloid bodies, and they may be in contact with basal cells at the dermoepidermal junction. The deposits can be minute, escaping detection. For this reason, macular amyloidosis is part of the differential diagnosis for the "normal skin" slide, sometimes called invisible dermatosis. Minimal epidermal changes, such as hyperkeratosis and hypergranulosis, are occasionally observed.

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