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Dermoscopy as a supportive tool to differentiate lichen amyloidosus from clinical mimickers

Author Affiliation(s)

Case Presentation

A 52-year-old woman presented with a 5-year history of itchy hyperkeratotic brownish papules on the legs ( Figure 1A ) dermoscopically typified by central brown globules surrounded by a pigmented halo ( Figure 1B ). Histology showed compact ortho-hyperkeratosis, irregular acanthosis, and amorphous eosinophilic material in the upper dermis which displayed positive Congo red staining and a green fluorescence under polarized microscopy ( Figure 1C ), consistently with a diagnosis of lichen amyloidosis.

Figure 1 .

(A) Clinical examination shows hyperkeratotic brownish papules on the legs (better seen in the inset). (B) Dermoscopically characterized by central brown globules surrounded by a pigmented halo (magnification in the inset). (C) Histology (H&E; 100x) reveals compact orthohyperkeratosis, irregular acanthosis, and amorphous eosinophilic material in the upper dermis which is typified by a green fluorescence under polarized microscopy (inset). (D–F) Dermoscopic features of the main clinical mimickers of lichen amyloidosus, namely, pretibial pruritic papular dermatitis (dotted vessels over a pinkish-white background – magnification in the upper right inset) (D), lichen myxedematous (white structureless areas) (E), and lichen planus (Wickham striae) (F).

Teaching point

Dermoscopy may be of aid in recognizing lichen amyloidosis by showing a peculiar pigmentary pattern resulting from the presence of melanin granules within amyloid deposition in dermal papilla (central globule) and basal layer hyperpigmentation/dermal pigment incontinence (peripheral pigmentation) [ 1 ] . Indeed, such dermoscopic clues are different from those visible in similar conditions, ie, pretibial pruritic papular dermatitis (dotted/globular vessels over a pinkish-white background) ( Figure 1D ), lichen myxedematous (white structureless areas) ( Figure 1E ), and lichen planus (Wickham striae) ( Figures 1F ) [ 1 , 2 ] .

References

  1. Other infiltrative conditions Errichetti E, Lallas A, Lallas A, Errichetti E, Ioannides D. Dermoscopy in General Dermatology.2018;:2-46.
  2. Dermoscopy for improving the diagnosis of pretibial pruritic papular dermatitis Errichetti E, Stinco G. Australas J Dermatol.2018;59(1):e74-e75. CrossRef PubMed

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