Langerhans Cell Histiocytosis of the Temporal Bone.

Langerhans cell histiocytosis involving the temporal bone region is uncommon and can resemble malignant neoplasms on imaging due to high cellularity. Although recognizing the presence of sharp margins with beveled-edges can be helpful, tissue sampling is often necessary for confirming the diagnosis. Cytology classically demonstrates kidney-bean shaped nuclei within the Langerhans cells and immunohistochemical staining is positive for S-100, peanut agglutinin (PNA), MHC class II, CD1a, and Langerin (CD 207). These features are exemplified in this sine qua non radiology-pathology correlation article.