The patient underwent stereotactic burrhole biopsy of the right frontal lesion. The lesion was noted to have invaded the dura mater. There was no pus or evidence of infection intra-operatively.

Histopathology

Sections demonstrate an infiltrate of cells including lymphocytes, neutrophils, eosinophils and atypical histiocytic cells. The latter demonstrate moderately variable ovoid reniform nuclei with occasional nuclear grooves. The cells have a small-moderate amount of amphophilic cytoplasm. There are some multinucleate histiocytes. Immunoperoxidase stains show positive staining for S100 and CD1a. Features in keeping with Langerhans cell histiocytosis.

Case submitted by Dr Chi Hau Tan and A/Prof John Troupis