PMC5943984_01
Radiologic and histologic features of PTGC IgG4-ROD (Case 1). Post-contrast MRI scans in coronal (A) and axial (B) sections show diffuse, right lacrimal gland enlargement with homogeneous contrast enhancement. Microscopically, the lacrimal gland shows fibrosis and enlarged, irregular lymphoid follicles with prominent mantle zones invading germinal centers (C). Numerous eosinophils and histiocytes are also present in interfollicular areas (D). Bcl-2 and IgD immunohistochemical stains highlight mantle zone lymphocytes within germinal centers (E, F). IgG4:IgG ratio is over 70% and >100 IgG4+ plasma cells per HPF are noted (G, H).
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A magnetic resonance imaging (MRI) scan showed an enlarged, right lacrimal gland measuring up to 2.3 x 1.1 x 2.2 cm, with low signal density on T1 and T2, and homogeneous contrast enhancement (Fig. 1A and B). An incisional biopsy was performed. IgG4 and IgG markers demonstrated an IgG4:IgG ratio over 70% and >100 IgG4+ plasma cells per HPF, which were mostly concentrated within germinal centers (Fig. 1C-H).
PMC5943984_02
Histologic features of PTGC IgG4-ROD (Case 2). The lacrimal gland and orbital tissue show focal fibrosis and is diffusely infiltrated by lymphoplasmocytic inflammation with prominent lymphoid follicles and abundant mantle zone lymphocytes penetrating germinal centers (A). Mantle zone lymphocytes are positive for Bcl-2 immunostain (B). More than 100 IgG4+ plasma cells are present per HPF, and IgG4:IgG ratio is over 80% (C, D).
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T-cell and B-cell population. There was a greatly increased number of IgG4+ cells (>100 per HPF) with an IgG4:IgG ratio of over 80% (Fig. 2).
PMC5943984_03
Histologic features of PTGC IgG4-ROD (Case 3). The fibroadipose tissue shows scattered, enlarged lymphoid follicles with prominent mantle zones invading germinal centers (A). Sparse eosinophils, small lymphocytes and histiocytes were also identified within the lesion (B). Bcl-2 immunoexpression is present in mantle zone lymphocytes (C). Over 100 IgG4+ cells per HPF are present (D).
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An IgG4 immunostain demonstrated over 100 positive plasma cells per HPF (Fig. 3).