Langerhans cell hyperplasia in scabies: a mimic of Langerhans cell histiocytosis

Aim:  In the absence of mites, the histologic diagnosis of human scabies can be difficult. Scabies can mimic a variety of inflammatory and lymphoproliferative disorders. It is under‐recognized that scabies can also mimic Langerhans cell histiocytosis. Methods:  Sixteen examples of scabies were reviewed histologically and immunohistochemically (CD1a, CD3, CD20, CD30 and S100). Results:  Immunohistochemical labeling showed florid CD1a and S100 positivity in most cases, indicative of Langerhans cell hyperplasia. Scattered CD30+ lymphocytes were also typically present, within a dense infiltrate, primarily composed of T lymphocytes and eosinophils. Conclusion:  Because of the prominent CD1a+/S100+ component, scabies can mimic Langerhans cell histiocytosis. This finding should be considered in conjunction with scattered CD30+ cells and clinical features to avoid misdiagnosis.