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.
Keywords: CT; Cytology; Langerhans cell histiocytosis; MRI; Pathology; Temporal bone.