Brain Pathology Case of the Month - February 2008

Contributed by 1Miletic H, 2Röling R, 1Stenzel W, 1Deckert M, 3Benz-Bohm G, 2Berthold F, 4Voges J
1 Department of Neuropathology, University of Cologne, Joseph-Stelzmann-Strasse 9, D-50931 Cologne, Germany
2 Children's Hospital, Department of Pediatric Oncology, University of Cologne, Kerpener Strasse 62, D-50924 Cologne, Germany
3 Department of Paediatric Radiology, University of Cologne, Joseph-Stelzmann-Strasse 9, D-50931 Cologne, Germany
4 Clinic for Stereotactic Neurosurgery, University of Cologne, Germany


An 8-year-old child presented with symptoms of raised intracranial pressure starting a few days before clinical presentation. Past medical history was significant for Diabetes insipidus centralis, which was diagnosed in February 2001 and treated with Minirin®. Neurological examination was normal.

The MRI scans showed a 25 mm space-occupying lesion with distinct contrast enhancement (Figure 1). The tumor was localized in the left insular region and attached to the Nucleus lentiformis and the left thalamic area. The T2 sequence demonstrated significant peritumoral edema with compression of the left ventricle and mid-line shift. (Figure 2). A primary brain neoplasm or an abscess were considered in the differential diagnoses. A stereotaxic biopsy was performed.


Histology showed a highly cellular lesion with a polymorphous mixed inflammatory infiltrate (Figure 3) consisting of histiocytes, mature lymphocytes, plasma cells and eosinophilic granulocytes (Figure 4). The histiocytes had round to oval, polymorphic nuclei and eosinophilic cytoplasm with indistinct margins, but a subpopulation had well defined borders. The histiocytes occasionally showed engulfed lymphocytes and plasma cells, a process referred to as emperipolesis (Figure 5).

Immunohistochemistry revealed S100+ (Figure 6), Vimentin+ and CD68+ histiocytes, while staining for the CD1a receptor was negative (Figure 7). GFAP immunostain detected reactive astrocytes. The inflammatory infiltrate consisted of CD45+ and CD3+ lymphocytes, CD138 + plasma cells and CD20 + B cells.


International Society of Neuropathology