‘Hints’ in the horn: diagnostic clues in the stratum corneum |
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Authors: | Ophelia Veraitch Raffaele Gianotti Gerardo Ferrara Carlo F. Tomasini Manuraj Singh Iris Zalaudek Catherine M. Stefanato |
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Affiliation: | 1. St John's Institute of Dermatology, St 2. Thomas' Hospital, London, UK;3. Dermatopathology Laboratory, Department 4. of Dermatology, Universita' degli Studi di Milano, Milano, Italy;5. Oncology Department, Anatomic Pathology Unit, Gaetano Rummo General Hospital, Benevento, Italy;6. Dermatopathology, University Hospital Città della Salute e della Scienza, Turin, Italy;7. Manuraj Singh, Department of Dermatology, St George's University Hospital, London, UK;8. Iris Zalaudek, Division of Dermatology, Non‐Melanoma Skin Cancer Unit, Medical University of Graz, Graz, Austria;9. Department of Dermatopathology, St John's Institute of Dermatology, St Thomas' Hospital, London, UK |
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Abstract: | The stratum corneum or horny layer is the uppermost layer of the epidermis, and is mainly responsible for the skin's barrier function. In spite of its complexity at the ultrastructural and molecular level, the features accessible to visualization on conventional histology are relatively limited. Nevertheless, knowledge of subtle clues that one may observe in the stratum corneum can prove useful in a wide range of situations in dermatopathology. We herein review a selection of common and rare entities in which the horny layer may reveal significantly important hints for the diagnosis. These clues include parakeratosis and its different patterns (focal, confluent, alternating, associated with spongiosis, epidermal hyperplasia or lichenoid changes), subcorneal acantholysis, infectious organisms in the stratum corneum (including fungal, bacterial and parasitic), thickening or thinning of the stratum corneum and the presence of different kinds of pigment. Even when normal, the horny layer may prove to be useful when seen in association with severe epidermal damage, a combination of features testifying to the acute nature of the underlying pathological process. |
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Keywords: | histopathology hyperkeratosis hypokeratosis parakeratosis stratum corneum |
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