Compressive Retinal Degeneration Due to a Large Lacrimal Gland Tumor

Abstract

A 64-year-old man presented with painless, progressive proptosis of the OS that lasted for several years. Clinical examination revealed severe downward deviation of the eyeball and a firm palpable mass above the eyeball (Fig. 1A). Visual acuity was “hand motion,” and the fundus could not be observed because of hypermature cataract. B-scan ultrasound revealed severe compression of the upper eyeball by the orbital mass (Fig. 1B), and MRI revealed a 3.5 cm-sized well-defined round mass above the eyeball (Fig. 1C,D).FIG. 1.: Preoperative findings of the patient and surgical specimen of the removed orbital mass. A, External photograph shows severe downward deviation of the left eye. B, B-scan ultrasound shows compression of the upper eyeball by the orbital mass. C, D, Magnetic resonance imaging (MRI) shows a 3.5-cm, well-defined, relatively homogeneous enhanced mass in the left superior orbit with severe inferior displacement of the eyeball. E, Gross specimen photograph of the well-encapsulated firm mass after complete excisional biopsy.Complete excisional biopsy of the mass was performed and diagnosed as pleomorphic adenoma of the lacrimal gland (Fig. 1E). Cataract surgery was performed after 2 months, and a degenerative retinal change was observed in the superior retina at the site of previous tumor compression (Fig. 2A). The optic disc showed no sign of optic atrophy (Fig. 2B). Optical coherence tomography (OCT) revealed dense sub-retinal pigment epithelium (RPE) material (red asterisk) and choroidal thinning (arrow heads) which were more prominent on the affected superior side (red dashed arrow) than inferior area (green dashed arrow, Fig. 2C). Choroidal thickness in the opposite eye was normal (Fig. 2D).FIG. 2.: Fundus photography and OCT images taken 8 months after orbital mass removal and 6 months after cataract surgery. A, Fundus photography shows well-demarcated retinal degeneration in the superior retina, previously compressed by the tumor (white dashed arrow: OCT scan location shown in Figure 2C). B, OCT evaluation of retinal nerve fiber layer shows retinal nerve fiber layer thickness within normal range. C, Vertical OCT scan of the left eye shows diffuse sub-RPE deposit in the superior retina (red asterisk); Choroidal thinning (arrow heads) is observed more than the opposite eye (D, arrow heads); Choroidal thinning seen prominently in the superior area (red dashed arrow) as compared to the inferior area (green dashed arrow). G, general; INT, inferior; N, nasal; NAS, nasal; NI, nasal inferior; NS, nasal superior; RNFLT, retinal nerve fiber layer thickness; SUP, superior; T, temporal; TI, temporal inferior; TMP, temporal; TS;temporal superior.The possibility of retinal degeneration by other etiologies cannot be completely ruled out. However, given the fact that degenerative retinal changes have been observed at previous tumor compression sites, the possibility of retinal degeneration by long-term compression can also be assumed. The possible pathophysiology is that the large orbital tumor mainly compresses the posterior ciliary arteries and affects choroidal circulation, while relatively conserving the central retinal artery traversing inside the optic nerve. Choroidal blood flow compromised over a long period can cause choroidal thinning and induce outer retinal and RPE degeneration. The diffuse sub-RPE deposits could be due to the outer retinal metabolite clearance failure caused by RPE dysfunction.