Presentation
Right eye exopthalmos for 4 years
Patient Data
Right eye proptosis. Hyperdense right extraconal orbital mass which is predominantly located at the lateral aspect with avid enhancement post contrast. No clear plane with adjacent enlarged right lacrimal gland or lateral and superior rectus muscles. Adjacent bone remodeling but no hyperostosis.
The aforementioned right extraconal orbital mass is T1 and T2 isointense to muscle with restricted diffusion. It demonstrates heterogeneous enhancement post contrast. Another smaller extraconal lesion with similar signal characteristics involves the right medial rectus muscle. No focal enhancing brain parenchymal lesion.
Differentials: orbital lymphoma, pseudotumor, and IgG4-related orbital disease.
Case Discussion
The patient underwent right anterior orbitotomy with incisional biopsy. Intraoperative finding: whitish firm mass, non-capsulated.
HISTOPATHOLOGY REPORT
Macroscopy: A brownish nodule measuring 15 x 10 x 7 mm, shows homogeneous, grayish cut surface. Bisected, entirely submitted in 1 block; external surface inked blue, rough area inked green.
Microscopy: Section shows lymphoid tissue adjacent to lobules of lacrimal glands, intersected by patternless bands of collagenous fibrosis. No obliterative phlebitis is apparent. The lymphoid tissue exhibits mild interfollicular expansion by heterogeneous population of lymphocytes. There is lymphoplasmacytic infiltrate, composed of CD3+ T-cells, CD20+ B-cells, and CD138+ mature plasma cells. The germinal centers harbor CD10+ and BCL6+ B-cells with preserved follicular dendritic meshwork demonstrated by CD23 immunostain, without expression of BCL2. Surrounding mantle zone is intact. Ki67 immunolabelling shows polarized proliferative activity in the germinal centers. No atypical lymphoid cells or plasma cells are apparent. Many of the plasma cells are IgG4+; areas of intense IgG4 foci show up to 150 IgG4+ plasma cells per high power field. The IgG4+/IgG+ plasma cell ratio is 50-60%. No obvious malignancy is seen in this biopsy.
Interpretation:
Tissue (right orbital mass), incisional biopsy: Histologically highly suggestive of IgG4-related disease.
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