Abstract
Purpose::
Idiopathic chronic inflammatory processes involving lacrimal gland and orbital soft tissues (orbital inflammatory pseudotumor; OIP) account for approximately 10% of biopsies for orbital masses. The lesions are progressive without treatment, but can be reversed by immune-mediated treatments. Etiology remains unknown. Purpose of the study was to review clinical, morphologic, immunophenotypic, and molecular genetic features of patients with OIP.
Methods::
25 patients (pts) were identified from an orbital pathology database. Biopsies (bxs) were evaluated for presence/ amount of fibrosis, follicular hyperplasia, myofibroblastic proliferation and infiltrate cell type. Immunophenotyping either by immunohistochemistry or flow cytometry were performed on 22 bxs. Molecular genetics for immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements were performed in 5.
Results::
There were 17 women and 8 men (median age 55 yrs, range 30-71). 21 pts (84%) presented with mass and/or proptosis, with diplopia or ambliopia in 10 (40%), and pain in 3 (12%). The process was centered in lacrimal gland in 20, extending also to orbital soft tissues (OST) in 4. OST involvement alone was seen in 20%, extension into cavernous sinus in12%, optic nerve sheath and lacrimal sac infiltration in 4%. Bilateral lesions were seen in 8 pts (32%). Bxs (n=19) showed moderate to marked lymphocytic infiltrates with few plasma cells (100%) and eosinophils (60%). Follicular hyperplasia was observed in 17 (89%): minimal (6; 32%), moderate (8; 42%), or marked (3; 16%). Fibrosis was observed in 14 (74%): minimal (4; 16%), moderate (5; 26%), or marked (6; 32%). Myofibroblastic proliferation was seen in 14 (74%): minimal (21%), moderate (47%) or marked (32%). Diffuse lymphoplasmacytic infiltrate mimicked lymphoproliferative disorder in 18%. Immunophenotyping (n=22) or flow cytometry (n=1) showed polyclonal T and B-cell population with polytypic plasma cells. Molecular genetics for TCR-gamma and Ig heavy chains revealed no gene rearrangements. No patients developed lymphoma in follow-up (1 to 36 months).
Conclusions::
OIP is a clinicopathologic condition presenting as mass lesion in the lacrimal gland and/or orbital soft tissues, causing proptosis and visual symptoms. It shows a wide morphological spectrum, from cellular lymphocytic infiltrates with associated follicular lymphoid hyperplasia to predominantly fibrosclerotic lesions. The differential diagnosis, both clinical and morphological, includes mostly lymphoma, from which can be distinguished by immunophenotyping performed on biopsy.
Keywords: orbit • lacrimal gland • immunohistochemistry