The “Wedge Sign”: An Imaging Sign for Aggressive Lacrimal Gland Disease

Abstract

Lacrimal gland carcinoma can form a triangle of tissue back to the orbital apex, intraconal spread apparently being prevented by the intermuscular septum. The "wedge sign" frequency is assessed in lacrimal carcinoma, lacrimal lymphoma, or dacryoadenitis. Retrospective masked review of images from patients with biopsy-proven lacrimal gland pathology. For each patient, the presence of a triangle of tissue between the lateral rectus and lateral orbital wall and the superior rectus and the orbital roof was assessed by masked review of computed tomography or magnetic resonance imaging. For the lateral compartment, the wedge was classified as "grade 1" if it just reached the sphenoidal trigone and "grade 2" if it was a complete triangle reaching the orbital apex. Comparison of proportions was made using the Fisher exact test, using an α risk of 0.05 as clinically significant. Imaging for 116 patients was reviewed: 39 with lacrimal gland carcinoma, 37 with lymphoma, and 40 with dacryoadenitis. The lateral wedge (grade 1 or 2) was most common in patients with carcinoma (16/39; 41%), was present in 11 of 37 patients (30%) with lymphoma, and was rarest in patients with dacryadenitis (6/40; 15%) (P= 0.033). The proportion in patients with carcinoma (41%) was similar to that in patients with lymphoma (30%) (P= 0.345); the proportion in patients with lymphoma (30%) was similar to that in patients with dacryoadenitis (15%) (P= 0.170), but carcinoma (41%) was significantly different from dacryoadenitis (15%) (P=0.013). The proportions for malignant lesions (carcinoma and lymphoma; 27/76, 36%) and benign dacryoadenitis (15%) were significantly different (P= 0.029). Likewise, a superior wedge, of any extent, was present in 10 of 39 carcinomas (26%), 2 of 40 dacryoadenitis (5%), and 6 of 37 lymphomas (16%) (P= 0.033). The "wedge sign" is most common in lacrimal gland carcinoma, but can occur in patients with severe forms of dacryoadenitis or lymphoma and generally indicates life-threatening lacrimal gland pathology that requires urgent biopsy. It is significantly more common in lacrimal gland carcinoma compared with dacryoadenitis and in malignancy (lymphoma and carcinoma) compared with inflammation.