Bilateral Optic Disc Swelling as the Presenting Sign of Pheochromocytoma in a Child

Abstract

Bilateral optic disc swelling in children is a relatively uncommon sign with a wide array of differential diagnoses. We describe a boy with bilateral optic disc swelling referred as a case of papilledema. However, upon careful ocular fundus examination, detection of discrete retinal nerve fiber layer and pigment epithelial changes at a distance from the optic discs raised the probability of malignant hypertension. This was confirmed by a simple blood pressure measurement. Judicious medical control of the hypertension and a full systemic evaluation led to successful surgical treatment of the inciting pheochromocytoma. A thorough history and meticulous clinical examination are irreplaceable, powerful diagnostic tools that can correctly direct the plan of management, thus preventing unnecessary investigations and delays or potentially serious complications.

Introduction

Bilateral optic disc swelling is a striking sign that can result from a variety of systemic pathologies or as a response to increased intracranial pressure. Optic disc edema always warrants a careful search for the cause, and the search should begin with a comprehensive history, careful clinical examination, and utilization of simple office tools before proceeding to more sophisticated or invasive investigations. We present a case of a youngster who was referred for management of presumed papilledema. Looking beyond the swollen optic discs and paying careful attention to subtle retinal and choroidal details led to the correct diagnosis of malignant hypertension. A simple blood pressure measurement has confirmed our impression. This report underscores the importance of a careful eye examination, the importance of considering hypertension in the pediatric age group, and the cost-effectiveness of having a sphygmomanometer in an ophthalmology office.

Case Presentation

A 9-year-old Saudi boy was referred for further management of “papilledema.” Initial workup at the referring institution included computed tomography, which did not disclose any abnormal findings.

On further inquiry, the child reported intermittent headaches and bouts of abdominal pain over the past 3 months. He had not been given any systemic medications and had no history of recent infectious or toxic exposure. His medical, surgical, and family histories were unremarkable.

The boy was conscious and oriented. Aside from the bilateral optic disc edema, the general neurologic examination, including that of other cranial nerves, was nonfocal.

Ophthalmologic examination revealed visual acuity of 20/20 in both eyes; color vision tested by Ishihara isochromatic plates was 9/10 in both eyes; visual fields by confrontation were full; and pupils were briskly reactive with no relative afferent papillary defect. The child was orthophoric with no restriction of extraocular motility. Anterior segment examination in both eyes was unremarkable.

Examination of the ocular fundus of both eyes after pharmacologic mydriasis revealed bilateral, mildly hyperemic, swollen optic discs with edema of the nerve fiber layer that obscured their margins (Figures 1 and 2). A subtle splinter hemorrhage at the level of the nerve fiber layer was also detected about 1 disc area away from the optic nerve head in the right eye (Figure 1).

Figure 1.

Right fundus photograph showing a hyperemic swollen optic disc that obscures the major blood vessels. Note the splinter hemorrhages at the level of the nerve fiber layer, more than 1 disc area away from the optic nerve head.

Figure 2.

Left fundus photograph depicting slightly milder optic disc swelling.

Of note, careful inspection of the area located temporal to the right macula disclosed several tiny, yellowish, well-defined spots at the level of the retinal pigment epithelium. Moreover, there was a bleb-like retinal elevation, measuring a half-disc area in size, adjacent to these spots (Figure 3).

Figure 3.

The right macula and a bleb of serous retinal detachment temporal to it, signifying acute infarction of the choriocapillaris (white arrow). Note the multiple discrete yellow-colored spots of retinal pigment epithelial atrophy corresponding to previous choriocapillaris infarction (black arrows).

The constellation of these, albeit discrete, signs has made increased intracranial pressure, and hence papilledema, a less likely diagnosis but has raised the possibility of systemic hypertension instead. The patient's blood pressure was checked and found to be 220/160, with a pulse rate of 140 bpm.

Upon further questioning, the boy's parents reported noticing recent frequent micturition and excessive sweating.

The patient was urgently referred to a general hospital with a pediatric intensive care facility where he was admitted for control of hypertension and further systemic investigations.

Abdominal ultrasonography and magnetic resonance imaging identified a right suprarenal mass, whereas urinary catecholamine level was abnormally high. A metaiodobenzylguanidine scan showed positive uptake within the mass, which supported a diagnosis of pheochromocytoma.

The patient underwent a laparoscopic right suprarenal adrenalectomy after successful control of blood pressure. A mass measuring 5 × 4.5 × 3 cm with cystic and solid components was excised; histopathologic examination confirmed the diagnosis of pheochromocytoma. The patient had an uneventful postoperative course and was consequently discharged.

Discussion

Bilateral optic disc swelling is an important clinical sign that can reflect a variety of inflammatory, infectious, toxic, metabolic, genetic, or vascular conditions, such as hypertension.[1] It can also result from idiopathic intracranial hypertension where it is labeled “papilledema,” a term that should not be used to describe bilateral, seemingly isolated, optic disc edema.

Patients with optic disc edema are often brought to the attention of ophthalmologists either as referrals from internists or as a first consultation by a patient with visual symptoms. The diagnosis of idiopathic intracranial hypertension readily prevails upon detection of optic disc edema associated with headache despite having well-established diagnostic criteria.[2] Without looking for other less obvious “clues” in the retina and choroid, the striking appearance of a bilateral swelling of the optic nerve heads can misdirect investigation toward less rewarding radiologic and invasive procedures.

While hypertension is a common systemic condition in adults, the pediatric equivalent is less common.[3] Thus, unless accompanied by more florid signs, such as a macular star and/or frank evidence of end-organ damage, hypertension in children may not be readily considered as a cause of optic disc edema unless the clinician keeps a high index of suspicion.[4,5] Unlike the previously reported cases, our patient exhibited only a few signs that could easily be missed on a cursory examination. Had the discrete findings discovered at the time of fundus examination been recognized and considered earlier, the patient could have been spared the time taken to diagnose and treat his potentially fatal condition. Furthermore, the line of investigation, once the diagnosis of hypertension has been established, could have been more appropriately tailored in the form of a neuroimaging technique that not only detects space-occupying lesions but can also identify a small optic nerve glioma that may coexist with pheochromocytoma.[6] A definitive evaluation of the brain and the optic nerves by contrast-enhanced magnetic resonance imaging with fat suppression techniques is an essential part of the workup of a child with optic neuropathy.

In the present case, the relatively distant location of the nerve fiber layer hemorrhage from the swollen optic nerve head represents a point by which hypertensive retinopathy can be differentiated from optic disc hemorrhage that may be associated with papilledema. In addition, signs of hypertensive choroidopathy were present, namely (1) depigmented spots at the level of the retinal pigment epithelium representing prior occlusions of the choriocapillaries; and (2) focal areas of ongoing dysfunction of retinal pigment epithelium that caused formation of a focal serous retinal detachment temporal to the macula.[7] This ultimately increased the likelihood of hypertension being the probable cause.

Thus, blood pressure measurement can save time, resources, and even the patient's life. Furthermore, should a clinician have a doubt about the nature of such choroidal findings, as those described here, obtaining a fluorescein angiogram can be helpful. In eyes with hypertensive choroidopathy, fundus fluorescein angiography reveals patchy filling defects that represent hypoperfusion of the choriocapillaris.[7]

The hypertensive episodes associated with pheochromocytoma are caused by abnormally increased sympathetic neuronal impulse frequency with excessive release of norepinephrine into the synaptic cleft with each impulse.[6] This is in contrast to the renin-angiotensin-aldosterone system derangement implicated as the cause of malignant hypertension associated with primary, or secondary, renal dysfunction.[8] Whether this difference in the mechanism of blood pressure elevation between the 2 conditions can affect the way optic disc ischemic injury ensues, and hence the visual prognosis, remains to be elucidated.[4,5]

Because optic disc edema in malignant hypertension is, generally, a sign of ischemia, rapid reduction of high blood pressure should be avoided to prevent optic atrophy and permanent vision loss.[8]

In conclusion, although uncommon in children, hypertension is an important entity to be considered. Implementation of national screening programs that incorporate annual pediatric physical examination would offer an excellent opportunity for early detection of hypertension, as well as other systemic conditions, in children. It is always advisable to check the blood pressure of each patient who presents with a presumptive diagnosis of papilledema. If a strong suspicion remains despite an initially normal blood pressure reading, blood pressure should be checked on several occasions to avoid missing cases of intermittent hypertension. Further ancillary testing should be guided by clinical judgment based on a good history taking and meticulous clinical examination.