Intracranial inflammatory pseudotumour related to IgG4: A very rare case

Caspian Journal of Internal Medicine 2024 (Spring); 15(2): 354-359 DOI: 10.22088/cjim.15.2.354 Case Report Intracranial inflammatory pseudotumour related to IgG4: A very rare case Ghassen Gader (MD) 1* Meissa Hamza (MD) 1 Ftima Jaziri (MD) 2 Ines Chelly (MD) 3 Ihsèn Zammel (MD) 1 Mouna Rkhami (MD) 1 Mohamed Badri (MD) 1 1. Department of Neurosurgery, Trauma and Burns Center, University of Tunis-El Manar, Faculty of Medicine of Tunis, Ben Arous, Tunisia 2. Department of Internal Medicine, Sadok Mokaddem Hospital of Jerba, Ben Arous, Tunisia 3. Department of Pathology, La Rabta Hospital, University of Tunis-El Manar, Faculty of Medicine of Tunis, Tunis, Tunisia * Correspondence: Ghassen Gader, Department of Neurosurgery, Trauma and Burns Center, University of Tunis-El Manar, Faculty of Medicine of Tunis, Ben Arous, Tunisia E-mail: Tel: +21 698604749 Abstract Background: Intracranial inflammatory pseudotumours (IPT) are rare entities that frequently lead to misdiagnosis with malignant lesions. The identification of these lesions is difficult, but important to avoid inadvertent iatrogenicity and to adjust therapeutic protocols. Case Presentation: We report the case of a 30-year-old man who presented a single tonic-clonic seizure. Brain imaging showed a right frontal lesion with intra and extra axial components. Facing the radiologic presentation, a brain tumor was suspected, thus the patient underwent surgery. Pathological exam concluded to a plasma cell granuloma. A whole-body CT-scan showed only a thoracic aortitis. Complete blood work studies came back negative. The patient was also tested for an array of antibodies among which antinuclear antibodies were positive (blood level superior to 1/100). CSF evaluation revealed clear fluid with normal glucose concentration, normal protein levels and lymphocytic pleocytosis. Finally, IgG-4 plasma levels were elevated which led to the diagnosis of an IgG4-RD. The patient was put under prednisolone with a favorable outcome. Conclusion: IPT have several etiologies, among which IgG4 related disease may be one of the less known as only 2 cases have previously been reported. Herein, we report a new case of a young man who presented for seizures related to an intracranial lesion of an IgG4 related disease. The challenge is to suspect such conditions to avoid unnecessary surgeries. Keywords: Inflammatory pseudotumor; IgG4; Neurosurgery; Internal Medicine. Citation: Gader Gh, Hamza M, Jaziri F, et al. Intracranial inflammatory pseudotumour related to IgG4: A very rare case. Caspian J Intern Med 2024; 15(2): 354-359. Intracranial inflammatory pseudotumors (IIPT) are among the differential diagnosis for central neurologic system (CNS) neoplasms. Despite their rarity, they may cause diagnostic issues as they can clinically and radiologically mimic intracranial tumors (1). They still remain of an unclear etiopathogeny. IIPT are mainly related to sarcoidosis and Histicytosis (Rosaï Dorfman disease) (1, 2). Intracranial localization for IgG-4 related disease (IgG4-RD) is very rare, as to the best of our knowledge, only two cases of IgG4 related intracranial inflammatory pseudotumors were reported to date within brain parenchyma (2). IgG4-RD was long considered as a single organ disease until 2003, when Kamisawa (3) suggested the clinicopathological entity ‘’IgG4-related autoimmune disease’’. A new understanding of this disease came to light. In point of fact, IgG4-related disease (IgG4-RD) is an immune mediated fibro-inflammatory disease of unknown cause characterized by the infiltration of one or more target organs by IgG4-positive plasma cells and lymphocytes (4–6). Received: 17 June 2022 Revised: 17 July 2022 Accepted: 5 Sep 2022 © The Author(s) Publisher: Babol University of Medical Sciences Caspian Journal of Internal Medicine 2024 (Spring); 15(2): 354-359 Intracranial inflammatory pseudotumour related to IgG4 Although it mostly affects digestive organs and salivary and lacrimal glands, a variety of central nervous system (CNS) manifestations are now recognized. These CNS manifestations are quite uncommon, among which hypophysitis and hypertrophic pachymeningitis are the most frequently reported lesions (2, 7). We herein report the third case of a recently admitted patient with a parenchymal IgG4- related inflammatory pseudotumor. Case Presentation We report the case of a 30-year-old man with no pathologic background, who presented a single tonic-clonic seizure four months ago. He complained of neither intracranial hypertension symptoms, nor visual symptoms. Neurological and physical exam were normal. Brain CT scan (figure 1) showed a right frontal lesion with intra and extra axial components. Brain MRI showed that the extraxial lesion was related to a hypertrophic pachymeningitis underlaying an intraparenchymal mass which showed a heterogenous enhancement following injection of Gadolinium. A finger-like edema signal was surrounding. At this stage, we mainly suspected a CNS lymphoma or a glioma, but the underlying pachymeningitis was against this hypothesis. The decision was to operate the patient for the most complete possible resection and to obtain the pathologic confirmation. Peroperative, the intra-axial lesion was greyish, non-hemorrhagic, and came easily into suction. 355 There was neither necrosis nor thrombosed veins. The pachymeningitis was extensive and had a meningioma-like aspect. We entirely removed the intra-axial portion, whereas the pachymeningitis was extending towards the fronto-basal region, thus inaccessible through our surgical corridor. Postoperative course was uneventful, and control CT scan (figure 2) showed no complications. The patient was discharged at the 4th postoperative day. Pathological exam (Figure 3) concluded to a plasma cell granuloma. A malignant blood disorder became the first working diagnosis, followed by infectious and inflammatory diseases. A whole-body CT-scan showed no more than thoracic aortitis. Complete blood work studies, including serology of infectious diseases, tumor markers screenings, anti-NMO antibodies and vasculitis tests were performed and came back negative. The patient was also tested for an array of antibodies among which antinuclear antibodies were positive (blood level superior to 1/100). A lip biopsy was also performed and showed no abnormalities. CSF evaluation revealed clear fluid with normal glucose concentration, normal protein levels and lymphocytic pleocytosis. Finally, IgG-4 plasma levels were elevated to 2g/L (normal values vary between 0.040 and 0.870 g/L) which led to the diagnosis of an IgG4-RD. The patient was put under 0.6mg/kg/d of prednisolone during 15 days followed by a progressive degression over 6 months. One year after surgery, the patient showed neither clinical nor radiological signs of recurrence. Figure 1. Axial section (A, B, C) and sagittal section (D, E) of a brain MRI on T1-WI without Gadolinium (A), with Gadolinium (B,D), T2-WI ( (...truncated)