Paediatric Primary Pachymeningeal Xanthogranuloma with Scattered Foci Displaying Reticulohistiocytoma-like Features

We report a unique case of a 4-year-old girl with an intriguing fibrohistiocytic tumour. Magnetic resonance imaging scans showed a dural mass of variegated intensity compressing the left occipital pole and apparently extending toward the superior sagittal sinus. Grossly, the cut surface of the surgical specimen was yellow, pale, and soft with reddish kernel-like crusts. Histologically, the yellow areas resembled cholesterol granulomas with widespread coagulative necrosis, cholesterol clefts, powdery calcification, foreign body-type giant cells, and foamy macrophages, while the scattered red spots contained numerous multinucleated giant cells of foreign-body and Touton types, the former with amphophilic to slightly eosinophilic cytoplasm. Immunoperoxidase reactions confirmed the expression of histiocytic markers and vimentin. As far as we know, no tumour displaying these peculiar morphological features has yet been described.