Man presents with 2-year history of binocular vertical diplopia
A 64-year-old white man was seen in the neuro-ophthalmology clinic for 2 years of binocular vertical diplopia more noticeable at distance.
He had no decrease in vision, eye pain, flashes, floaters or ptosis. There was no recent history of trauma. Systemic review of systems was negative for dysphagia, dyspnea, muscle weakness or any other neurologic symptoms. Ocular history included cataracts and mild meibomian gland dysfunction. Medical history included low-grade transitional cell carcinoma of the bladder currently in remission, hypertension and hypercholesterolemia. Medications included amlodipine 2.5 mg, atorvastatin 80 mg, aspirin 81 mg, vitamin B12 and vitamin D. There were no pertinent surgical or family histories and no known allergies.
Images: Simon D. Archambault, MD, MSc, Laurel N. Vuong, MD, and M. Reza Vagefi, MD
Examination
On examination, best corrected visual acuity was 20/20 in both eyes. Confrontation visual fields, color vision and pupillary exam were normal in both eyes. IOPs were within normal limits. There was painless limitation in supraduction in the right eye, and extraocular movements were full in the left eye. Stereopsis was preserved. Maddox rod testing showed a right hypotropia present in primary gaze and worse in upgaze. The right eye was 5 mm proptotic with Hertel exophthalmometry measurements of 20 mm in the right eye and 15 mm in the left eye. There was bilateral upper eyelid retraction with a margin reflex distance 1 of 6 mm in the right eye and 6.5 mm in the left eye. Anterior segment slit lamp examination was notable for mild bilateral conjunctival injection and cataracts in both eyes. Funduscopic examination showed normal optic nerve, macula and retinal vasculature in both eyes.
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Binocular vertical diplopia
The patient’s findings were highly suggestive of thyroid eye disease (TED) given his age, limitation in supraduction, proptosis, conjunctival injection and lid retraction. However, a neoplastic process was also considered, including a benign orbital tumor (cavernous venous malformation, schwannoma, solitary fibrous tumor, primary lacrimal gland tumor, sphenoid wing meningioma, primary optic nerve sheath meningioma). Due to the length of duration of symptoms, a malignant process such as lymphoma or primary carcinoma of the lacrimal gland was less likely. However, given the history of bladder cancer, metastatic disease was also considered.
Workup and management
The patient underwent MRI of the brain and orbits with and without contrast, which demonstrated a 2.1 cm × 1.6 cm × 1.8 cm well-defined soft tissue density mass lesion in the superior lateral anterior right orbit measuring 47 Hounsfield units with smooth margins involving both the intraconal and extraconal spaces. The mass was mildly heterogeneous on MRI with T1 hypointensity and T2 hyperintensity (Figure 1). No bony erosion or calcifications were present. A CT scan of the head, conducted to better visualize the orbital bones, demonstrated mild thinning and remodeling of the orbital roof, which likely indicated chronicity (Figure 2). At this time, he was referred to an oculofacial plastic surgery service for surgical planning and management.
The patient underwent orbital surgery to remove the neoplasm via a lateral orbitotomy with an orbitozygomatic osteotomy. Using careful blunt dissection, the neoplasm was removed in a single piece without violation of the tumor and sent to pathology (Figure 3). The neoplasm demonstrated epithelial cells arranged forming tubules and ductulus surrounded with myoepithelial cells consistent with a pleomorphic adenoma of the lacrimal gland (Figure 4a). The pathology report demonstrated excision of the entire lesion with a single area where the lesion was within 0.1 mm of the pseudocapsule (Figure 4b).
Discussion
This case represents a prime example of how clinical examination in combination with imaging and pathology are required to identify the etiology of orbital lesions. Initially, it was thought that the patient likely had TED given the clinical presentation. TED is far more common with an incidence in men of three in 100,000 (McAlinden). The MRI, however, revealed that the etiology was in fact an orbital mass that was highly suspicious for a primary lacrimal gland tumor given its appearance and location. Histopathologic evaluation confirmed a pleomorphic adenoma of the lacrimal gland.
Primary lacrimal gland tumors are exceedingly rare neoplasms affecting only one in 1 million people (Shields and colleagues). They are classified by the metaplastic cell lineage into two types: epithelial and non-epithelial tumors. Epithelial tumors comprise only 30% of all primary lacrimal gland tumors. While 40% of these epithelial tumors are malignant, 60% are benign and include neoplasms such as pleomorphic adenomas, ductal epithelial cysts, oncocytomas, cystadenolymphomas, myoepitheliomas and sialoblastomas (Shields and colleagues). Of these benign tumors, pleomorphic adenomas are most common.
As demonstrated in this patient, a pleomorphic adenoma of the lacrimal gland (PALG) is composed of a neoplastic proliferation of epithelial cells forming ducts surrounded with myoepithelial cells (Weis and colleagues). The tumor is encapsulated in a pseudocapsule containing only fibrous elements and lacking an epithelium seen in true capsules, making it more porous and thus at greater risk for tumor spillage during removal (Shields and colleagues; Weis and colleagues). Therefore, it is essential during tumor removal to gently deliver it en bloc and not violate the pseudocapsule as retained metaplastic epithelial cells bestow the highest risk for tumor reoccurrence (Shields and colleagues). PALG reoccurrence is always associated with a higher chance of malignant transformation, which has a far worse prognosis and elevated morbidity and mortality (Shields and colleagues).
While in the present case the entire tumor was removed without violating the pseudocapsule, the patient had one area where the lesion was within 0.1 mm of the pseudocapsule. With full lesion excision, repeat MRI is typically not pursued. However, in this case, it was felt that continued monitoring of the orbit with routine imaging to ensure that there is no reoccurrence would be of benefit. An orbital MRI will be performed every 6 months for the next 3 years, as reoccurrence rates are highest in the first 24 months postoperatively. It should be noted that tumor reoccurrence has been observed as far as 60 years after initial resection (Shields and colleagues). It will also be essential for the patient to monitor for any new signs of proptosis, diplopia or lid abnormalities moving forward.
Case resolution
At the 2-month postoperative appointment, the patient’s right orbit had healed well. The diplopia, supraduction deficit, lid retraction and proptosis had fully resolved. Vision remained 20/20 in both eyes. He will continue to have serial MRIs over the next 2 years to ensure no evidence of reoccurrence.
- References:
- McAlinden C. Eye Vis (Lond). 2014;doi:10.1186/s40662-014-0009-8.
- Shields JA, et al. Ophthalmic Plast Reconstr Surg. 2004;doi:10.1097/01.IOP.0000103003.87842.BB.
- Shields JA, et al. Ophthalmology. 2004; doi:10.1016/j.ophtha.2003.01.002.
- Weis E, et al. Arch Ophthalmol. 2009;doi:10.1001/archophthalmol.2009.209.
- For more information:
- Edited by William W. Binotti, MD, and Julia Ernst, MD, PhD, of New England Eye Center, Tufts University School of Medicine. They can be reached at william.binotti@tuftsmedicine.org and julia.ernst@tuftsmedicine.org.
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