Not all orbital inflammations in the COVID-19 era are due to mucormycosis – A case of orbital pseudotumour leading to vision loss

Abstract

A 57-year-old male patient with type 2 diabetes mellitus who had survived severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disease (COVID-19) presented with loss of vision in the right eye (RE) of 20-day duration. The patient had been diagnosed elsewhere with orbital mucormycosis and had been treated for it. The patient developed vision loss in RE 1 week after the initiation of treatment. At the time of presentation in our institute, vision in RE had reduced to no perception of light. Examination showed a relative afferent pupillary defect and pale optic disc in RE. Gadolinium-enhanced contrast magnetic resonance imaging of the brain, orbit and paranasal sinuses suggested perineuritic type of idiopathic orbital inflammation. In the present COVID-19 scenario, diagnosis other than mucormycosis should be kept in mind when dealing with cases of orbital inflammation.

INTRODUCTION

Rhino-orbital cerebral mucormycosis has become a matter of concern in the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disease (COVID-19) setting in India after its exponential increase in incidence over the past few months, especially in the presence of associated risk factors such as diabetes and corticosteroid use.^[1,2] Orbital involvement presenting as orbital inflammation is the second-most common presentation after nose and paranasal sinuses (PNSs).^[1] It is rapidly progressive and delay in diagnosis can be both vision and life-threatening. With the surge in mucormycosis cases, other aetiologies which can cause orbital inflammatory disease can be neglected and delay in diagnosis and management can be associated with serious implications. Thus, here we report a case of orbital pseudotumour in a post-COVID-19 positive patient which presented a diagnostic dilemma and was treated for mucormycosis, ultimately leading to vision loss.

CASE REPORT

A 57-year-old male patient with type 2 diabetes mellitus who had survived COVID-19 presented to our outpatient department with loss of vision in the right eye (RE) for 20 days. Ten days before vision loss, the patient had consulted elsewhere for right-sided headache and periorbital swelling. The patient had recovered from COVID-19 two weeks before the onset of symptoms. He had undergone home isolation and had been treated with oral azithromycin, paracetamol, montelukast, ivermectin and vitamin supplements. Best-corrected visual acuity (BCVA) recorded at that time was 20/60, N12 in RE and 20/32, N6 in the left eye (LE). Pupillary reaction was normal in both eyes while anterior segment examination in RE revealed mild proptosis, lid oedema, conjunctival congestion and chemosis with limitation of extraocular movements (Figure 1a). Intraocular pressure recorded was 28 and 15 mmHg in RE and LE, respectively. Rest anterior and posterior segment examination was mentioned to be normal. Since the patient was a known case of COVID-19 with diabetes as a risk factor, right-sided mucormycosis was suspected.

Figure 1: Clinical photograph at the time of presentation elsewhere showing proptosis, lid swelling, conjunctival chemosis and congestion in the right eye (a). Magnetic resonance imaging at the time of presentation elsewhere showing proptosis (yellow arrow) and diffuse fat stranding in the intraconal compartment of the right orbit (white arrow) (b)

Diagnostic nasal endoscopy was performed and the sample was sent for potassium hydroxide mount, histopathology and fungal culture, where no organism was detected. Following this, they performed plain magnetic resonance imaging (MRI) of the orbit and PNS which showed diffuse fat stranding in the intraconal compartment of the right orbit with mild proptosis (Figure 1b). With these findings, the diagnosis of possible rhino-orbital mucormycosis was made and the patient was started on conservative treatment with topical moxifloxacin, oral linezolid, itraconazole and serratiopeptidase. The patient developed sudden-onset vision loss in RE one week after the initiation of treatment.

When the patient presented to us, BCVA in RE was no perception of light and LE was 20/32, N6. On examination, a relative afferent pupillary defect was noted in RE with normal pupillary reaction in LE. Anterior segment examination of both eyes was within the normal limits with extraocular movements full and adequate in all directions (Figure 2a). Posterior segment examination of RE showed disc pallor with drusens in the macula (Figure 2b). Gadolinium-enhanced MRI of the brain, orbit and PNS was done where marked fat stranding in the retrobulbar intraconal compartment extending posteriorly along the enlarged right optic nerve till the orbital apex with post-contrast enhancement of the optic nerve sheath was noted suggesting perineuritic type of idiopathic orbital inflammation (Figure 2c). A PNS and brain study was normal. Detailed investigations were done to rule out any infection, infiltration or tumour. Complete blood counts, erythrocyte sedimentation rate, renal function tests, anti-nuclear antibody, thyroid profile, serum angiotensin-converting enzyme and chest X-ray were normal. Thus, after ruling out all other possibilities and on the basis of radiological imaging, the diagnosis of orbital pseudotumour in RE was made. For confirmation, an orbital biopsy was planned, but the patient refused.

Figure 2: Clinical photograph of the patient at the time of presentation in our institute showing resolved lid oedema and conjunctival chemosis in the right eye (a). Colour fundus photograph of the right eye showing pale optic disc and drusens in the macular area (b). Gadolinium contrast-enhanced magnetic resonance imaging of the right eye showing post-contrast enhancement of optic nerve sheath (black arrow) suggestive of perineuritic type of idiopathic orbital inflammation (orbital pseudotumour) (c)

Since our patient had no vision potential, the eye was quiet and associated risk factors of diabetes and post-COVID were present, no systemic steroid therapy was initiated for him and he was counselled to report as soon as any signs of inflammation appear.

DISCUSSION

Orbital pseudotumour or idiopathic orbital inflammation is a non-specific inflammation of the orbit where local and systemic causes cannot be identified. It is the third-most common orbital disease accounting for 4.7%–6.3% of orbital disorders after Graves’ orbitopathy and lymphoproliferative diseases.^[3] It is more commonly unilateral and the usual age of presentation is in the fifth decade^[4] which was consistent with our case. It can have varied presentations depending on the site involved ranging from diffuse to specific orbital tissues such as lacrimal gland, orbital fat, optic nerve sheath, orbital apex or extraocular muscles. It is a diagnosis of exclusion and other possible causes such as malignancy, inflammation and infection should be ruled out.^[4]

Although benign with spontaneous remission occurring without treatment also, it can have a clinically malignant course. About 10%–20% of patients can have reduced vision with complete loss of vision being very rare^[5] with only two previously published reports.^[6,7] Possible causes of vision loss include inflammation of the optic nerve, crowding at orbital apex and either optic nerve stretching or compression.^[6,7] A case of orbital inflammation with optic perineuritis associated with COVID-19 has been reported, but the vision at presentation was 20/30 with full improvement with steroids.^[8]

In our case, there was a delay in diagnosis as the patient was suspected to be a possible case of mucormycosis and line of management was planned accordingly. This might have led to an increase in inflammation extending up to the orbital apex with perineuritis component as evident on the MRI which caused vision loss. Alternate possibility can be due to optic nerve stretching due to proptosis or orbital compartment syndrome. Systemic steroids are the keystone in the treatment of orbital pseudotumour in the acute phase.^[5] Initiation of steroid therapy in the acute phase could have resulted in a decrease in inflammation with possible maintenance of good vision. Since the patient had no active inflammation and no vision potential on presentation at our institute, steroid therapy was not considered.

In COVID times, although rhino-orbital mucormycosis has been on a rising trend, we should broaden our diagnostic horizon and consider other differentials also. Early diagnosis and prompt treatment can help in salvaging vision in most of these cases.

Author declaration

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Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed.

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Nil.

Conflicts of interest

There are no conflicts of interest.