Which histologic findings are characteristic of pitted keratolysis?

Updated: Jul 30, 2018
  • Author: Linda J Fromm, MD, MA, FAAD; Chief Editor: Dirk M Elston, MD  more...
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If a cutaneous biopsy is performed, histological evaluation of hematoxylin and eosin (H&E)–stained plantar skin reveals a crater limited to the stratum corneum (see the image below).

Histopathology reveals a crater limited to the thi Histopathology reveals a crater limited to the thick stratum corneum of the epidermis.

The microorganisms, cocci, and filamentous forms may be seen with H&E staining, but they are detected more easily with Gram stain, periodic acid-Schiff stain, or methenamine silver stain. In 2000, Wohlarb et al reported 2 histologic types. [24] The superficial minor type is coccoid bacteria found extracellularly on the surface of the stratum cornea. The classic or major type is coccoid and septated bacterium forms intracorneocytically in the horny layer. In patients with associated foot pain and with erythematous-to-violaceous macular lesions and pits, histological examination reveals only a mild dermal inflammatory reaction. In 2000, de Almeida et el studied pitted keratolysis with electron microscopy and noted transverse septated bacterium in tunnellike openings on the floor of the pits. [37]

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