Brain Pathology Case of the Month - March 2016

Contributed by Caroline Koopmansch1, Nicky DíHaene1, Delfyne Hastir1, Niloufar Sadeghi2, Calliope Maris1, Isabelle Salmon1
1Laboratory of Pathology, 2Department of Radiology, Erasme University Hospital, Free University of Brussels (ULB), Brussels, Belgium


A 63-year-old woman developed deterioration of her general condition over a three-week period, with apathy and drowsiness. Major history included rheumatoid arthritis treated by corticoids and anti-TNFα and right breast tumorectomy. Physical examination revealed tachypnea, dyspnea, Cushingoid facies, bilateral rhonchi and bilateral edema of the lower limbs. Neurologic examination revealed drowsiness. Further tests brought out atrial fibrillation, cardiac failure and inflammatory syndrome.

CT scan of the brain showed a large area of hypodensity in the right frontal lobe with mass effect associated with meningeal enhancement (Figure 1). MRI revealed an area of high signal intensity on FLAIR images in the right frontal lobe as well as in the left frontal sulci (Figure 2). On T1-weighted images with contrast a cortical and leptomeningeal enhancement was also found (Figure 3). These images suggested bilateral frontal meningoencephalitis, predominating over the right side, consistent with an infectious or an inflammatory disease.

CSF protein level was 59 mg/dl, glucose level at 93 mg/dl and cytology showed a reactive process with presence of numerous lymphocytes and plasma cells. At this stage, differential diagnoses were progressive multifocal leukoencephalopathy (PML), lymphoma and vasculitis. FDG-PET of the head revealed high glucose uptake in right frontal lobe, consistent with a lymphomatous process or encephalitis (Figure 4). Biopsies of brain tissue and dura mater from right frontal lobe were obtained.


Grossly, the biopsy specimen was a fragment of dura mater and multiple solid and yellowish fragment of brain tissue, altogether measuring 3 x 3 x 1 cm. Smears revealed glial cells without atypia, lymphocytes, plasma cells and neutrophils within a necrotic background. Histologically, the fragment of dura mater was thickened with necrotizing granulomas surrounded by histiocytes, lymphoplasmocytic infiltrates and giant cells involving the leptomeninges with extension to the brain parenchyma (Figures 5, 6, 7 and 8). Vasculitis and spongiosis were also observed in the parenchyma (Figure 9). Special stains (PAS, Gomori-Grocott and Ziehl-Neelsen) were negative for fungi and mycobacterium. CD68 immunohistochemical staining confirmed the presence of histiocytes surrounding granulomas' necrosis (Figure 10). CD3 and CD20 immunohistochemical stainings confirmed the polymorphous population of lymphocytes (T and B). What is your diagnosis?


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