PMC8120283_01
Brain MRI images showed intracranial mass located at middle of upper clivus region. (A, B). The lesion located at middle of upper clivus region presented with isointense signal in T1-weighted MRI image (A, the arrow), and hypointense signal in T2-weighted MRI image (B, the arrow); (C, E): The mass was uniformly enhanced after contrast MRI scan, and the base of the tumor was extensively stick to the adjacent dura and brain stem, showing meningeal tail sign (the arrow in D), and meningioma was highly suspected. (F). CT bone window showed no bone invasion. (G, I). The MRI showed partial resection of the lesion.
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Magnetic resonance imaging (MRI) of the skull base revealed a predominantly hypointense signal on T1- and T2-weighted images from a mass located in the middle of the upper clivus area, and it was homogenously enhanced after contrast MRI; meningioma was highly suspected ( Figures 1A-F ). As inflammatory lesions may be sensitive to glucocorticoids, the lesion was partially resected owing to its tenacious texture and close adhesion to the brain stem ( Figures 1G-I ).
Intra-operative condition of the lesion located at middle of upper clivus region. (A) the lesion was very tough and firm (the arrow); (B) the lesion was stick to the brain stem and basal artery (1: brain stem; 2: basal artery; 3: abducent nerve).
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Histological features of the lesion revealed an IgG4-related inflammatory pseudotumor. (A, B) Hematoxylin and eosin (H&E) stain showed the lesion was composed of sclerosing fibrosis associated with dense lymphoplasmacytic infiltration (A: x40; B:x100); (C, D) Immunohistochemical analysis revealed over 400 IgG4-positive cells per high-powered field and a high IgG4/IgG ratio (C, IgG, x200; D, IgG4, x200). (E) Immunohistochemical staining of CD38; (E) Immunohistochemical staining of Ki-67. (F) Immunohistochemical staining of Ki-67.
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The histopathological findings revealed an inflammatory pseudotumor involving the clivus, with sclerosing fibrosis mixed with lymphocytes and IgG4-positive plasma cells infiltrating into the tissues ( Figure 3 ). Hematoxylin and eosin (H&E) stain showed the lesion was composed of sclerosing fibrosis associated with dense lymphoplasmacytic infiltration ( Figures 3A, B ). IgG4-positive cells per high-powered field and a high IgG4/IgG ratio ( Figures 3C, D ). Immunohistochemistry revealed positivity for vimentin, EMA, CD3, CD20, CD38, CD68, kappa, lambda and IgG4 but negativity for PAS and CD34. and the Ki-67 index was 10% ( Figures 3E, F ).