CD30 positive anaplastic large-cell lymphoma mimicking Langerhans cell histiocytosis.

The presence of CD 1a+ dendritic cells (DC) has been well described in T-cell lymphoproliferative disorders, and the presence of large numbers of DCs has rarely been reported as a mimicker of Langerhans cell histiocytsis (LCH). We present the case of a 56-year-old female with a solitary nodule on the chin whose case was referred to our institution for confirmation of the diagnosis of LCH. Skin biopsy showed an ulcerated nodule containing a wedge-shaped infiltrate comprised of large atypical cells and cells with prominent grooved nuclei. The constellation of histologic and immunologic features favored a CD30 lymphoproliferative disorder of T-cell lineage even though there were accompanying numerous dendritic histiocytes and CD1a positive Langerhans cells. The sheets of CD30 positive atypical lymphoid cells which express T-cell markers were consistent with CD30 positive lymphoproliferative disease and favor CD30 positive anaplastic large-cell lymphoma (ALCL) over Langerhans histiocytosis. The absence of Anaplastic Lymphoma Kinase (ALK) staining favored a primary cutaneous origin. This case signifies a CD 30+ ALCL of the skin which histopathologically mimics a LCH. Ezra N, Van Dyke GS, Binder SW. CD30 positive anaplastic large-cell lymphoma (ALCL) mimicking Langerhans cell histiocytosis (LCH).