Brain Pathology Case of the Month - October 2017

Contributed by Luca Bertero1, Francesco Zenga2, Francesca Maletta3, Rebecca Senetta4, Paola Cassoni1
1 Division of Pathology, Dept. of Medical Sciences, University of Turin, Turin, Italy
2 Division of Neurosurgery, Dept. of Neurosciences, University of Turin, Turin, Italy
3 Division of Pathology, Cittą della Salute e della Scienza University Hospital, Turin, Italy
4 Division of Pathology, IRCCS Candiolo, Candiolo (Turin), Italy


A 68-year-old woman was admitted to the Department of Neurosurgery because of sudden development of fluent aphasia after a history of about 20 days of right inferior-temporal quadrantanopia with left eye sight deterioration. MRI found a 3 cm hyperintense, contrast-enhancing mass in the left posterior-lateral orbital wall protruding through the optic foramen and displacing the temporal lobe (Fig. 1a). A meningioma was suspected and patient underwent left pterional craniotomy combined with a lateral orbitotomy in order to remove both the intraorbital and the intradural components of the tumor. The mass showed neither a clear dural implant, nor a well-defined dissection plan from the brain parenchyma, raising the suspicion of a lymphoproliferative disorder. Since the intraoperative pathological findings from frozen sections were suggestive for an inflammatory disease, only a partial resection was achieved to avoid damage to the optic nerve. The patient recovered well and was discharged with a left eye sight improvement.


Hematoxylin and eosin (H&E) intraoperative frozen sections showed a sclerotic tissue with a chronic inflammatory infiltrate without significant atypia, mitoses or necrosis. Further resection of the lesion was therefore completed and more pathological material was submitted. Histological examination after FFPE processing showed a fibrotic tissue with storiform pattern, a chronic inflammatory infiltrate with a background of numerous plasma cells with a balanced Kappa/Lamba ratio and a high count of IgG4-positive elements (up to 40/HPF) (Fig. 1b).

Examination of the additional submitted samples pointed out a significantly different finding: H&E sections showed a hypercellular connective tissue with numerous histiocytes, with large nuclei and wide, foamy or eosinophilic, cytoplasm, arranged in small groups (Fig. 1c). Emperipolesis was diffusely observed (Fig. 1d) and S100 staining was positive in these cells. A background of small lymphocytes and numerous IgG4-positive plasma cells (Fig. 1e), as on the frozen sections, was also present, with an average IgG4+/IgG+ ratio > 40% by counting the IgG4+ "hot spots". What's your diagnosis?


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