Overexpression of linker for activated T cells, cyclooxygenase-2, CD1a, CD68 and myeloid/histiocyte antigen in an inflamed seborrheic keratosis

Context: Inflamed seborrheic keratoses are generally associated with the accumulation of variable numbers of lymphocytes and histiocytes in the superficial dermis. The precise immunologic mechanism of this histologic phenomenon is not known Case Report: A 62-year-old male presented with a patch on the right neck with additional features of inflammation. Skin biopsies for hematoxylin and eosin examination, as well as for immunohistochemistry analysis were performed. Results: H&E staining demonstrated classic features of an inflamed seborrheic keratosis. Overexpression of LAT, COX-2, CD1a, and CD68 was noticed in the inflammatory infiltrate. A strong presence of CD1a was also seen in the epidermis suprajacent to the inflammation. Myeloid/histiocyte antigen was strongly expressed by the keratinocytes. Conclusion: A complex immune response seems to be involved in the pathophysiology of an inflamed seborrheic keratosis.