Which histologic findings are characteristic of actinic annulare?

Updated: Oct 29, 2018
  • Author: Ruby Ghadially, MBChB, FRCP(C)Derm; Chief Editor: William D James, MD  more...
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Answer

Actinic annulare, also known as annular elastolytic giant cell granuloma, may lack the classic palisaded arrangement observed in granuloma annulare. Although elastosis is abundant in the mid dermis outside the granuloma, elastic tissue is absent from the center of the annulus. Giant cells frequently abut elastotic tissue, and phagocytosed elastotic fibers are noted in histiocytic cells at the advancing edge. Collagen has a normal appearance outside the lesion but a finely fibrillar pattern within the annulus. Mucin deposition is not increased as it is in granuloma annulare. Thus, actinic annulare can be distinguished histologically from granuloma annulare by a preponderance of giant cells in relation to elastotic tissue, by absence of mucin, and, occasionally, by absence of palisading histiocytes around granulomas.


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