Metachronous skull eosinophilic granuloma. Patient 27 presented with a tender palpable frontal mass 16 months after he had been treated for nasopharangeal carcinoma. Radiography of the skull demonstrated two bony erosions (arrows in a) in his frontal and occipital bone. The lesions were contrast-enhanced on the magnetic resonance image (arrow in b and c). Histological examination demonstrated Langerhans cells and eosinophils with positive immunohistochemistry for S100 and CD1a.