Which histologic findings are characteristic of Wells syndrome (eosinophilic cellulitis)?

Updated: Mar 23, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Dirk M Elston, MD  more...
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Skin biopsy specimens of Wells Syndrome (eosinophilic cellulitis) show a dermal infiltrate of eosinophils, histiocytes, and eosinophil debris between collagen bundles that forms flame figures. During the acute early phase, the dense infiltrate of degranulating eosinophils is usually located in the epidermis and the dermis, although it occasionally extends into the subcutaneous tissue and the underlying muscle. [50, 51, 52]  See the images below.

A superficial and deep perivascular and interstiti A superficial and deep perivascular and interstitial inflammatory pattern. Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/t/wellsfigure2.jpg).
Superficial and deep perivascular and interstitial Superficial and deep perivascular and interstitial inflammatory pattern extending into the subcutaneous tissue. Courtesy of DermNet New Zealand (https://www.dermnetnz.org/assets/Uploads/pathology/t/wellsfigure3.jpg).

Vesiculation can occur. The blisters contain eosinophils and are predominantly subepidermal and, occasionally, multiloculated and spongiotic. The location of the infiltrate is correlated with the different clinical features.

After weeks, the flame figures are seen, along with a palisade of histiocytes and giant cells around some collagen fibers. With immunofluorescent stains, eosinophil major basic protein is identified in the granules of the flame figures. [53] On electron microscopy, the collagen fibers are intact; this finding suggests that an initial degeneration of collagen is not a factor in initiating the formation of flame figures.

Although the histopathologic findings of eosinophilia, histiocytes, and flame figures are characteristic of Wells syndrome, they are also found in other conditions, including bullous pemphigoid, eczema, tinea infection, dermatitis herpetiformis, scabies, and insect bites. [54, 55]

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