September 22, 2020
6 min read
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Woman presents with new-onset conjunctival pigmentation

The patient had a mechanical fall with blunt trauma to the left eye 9 months earlier.

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A 78-year-old woman presented to the Lahey Hospital Cornea Service for evaluation and management of new conjunctival pigmentation of the left eye.

Christine Benador-Shen
Christine Benador-Shen
Malgorzata Dymerska Peterson
Malgorzata Dymerska Peterson

She described decreased vision of the left eye associated with mild photophobia. She had no eye pain, redness, flashes, floaters or vision changes in the right eye.

Nine months before presentation, she had a mechanical fall with a blunt trauma injury to her left eye. Per the patient’s outside hospital records, immediately after the ocular injury, her vision was light perception in the left eye with an IOP of 49 mm Hg. Her exam showed bullous subconjunctival hemorrhage, a 1.5 mm layering hyphema and a left orbital floor fracture. Her elevated IOP and hyphema were treated with ocular antihypertensive drops and cycloplegics. Her orbital floor fracture did not require surgical repair. Her ocular history was also notable for bilateral cataract extraction with IOL implantation several years prior, posterior capsular opacification of the left eye and posterior vitreous detachment in both eyes.

Her medical history included atrial fibrillation, chronic obstructive pulmonary disease, obstructive sleep apnea, obesity, breast cancer in remission, basal cell carcinoma of the nose, hypertension and hyperlipidemia. She had a 31 pack-year history of cigarette smoking. Medications included rivaroxaban, verapamil, venlafaxine, pravastatin, omeprazole, metoprolol, lisinopril, furosemide, ferrous sulfate, calcium carbonate, albuterol, anastrozole and supplemental nasal cannula oxygen as needed.

speckled conjunctival pigmentation
Figure 1. Slit lamp photographs of the left eye revealing speckled conjunctival pigmentation and total iris dislocation (a), inferior and inferotemporal speckled conjunctival pigmentation (b) and superotemporal conjunctival pigmentation (c).

Source: Nisha S. Dhawlikar, MD, MPH, and Naveen K. Rao, MD

Examination

When evaluated at Lahey Clinic, 9 months after ocular trauma, the patient’s visual acuity was 20/30 in the right eye and 20/40 in the left eye. IOPs were normal. The right pupil was round and briskly reactive to light with no afferent pupillary defect, whereas the left iris was not present. Confrontation visual fields and motility were full. External examination of the lids, lashes and adnexa was unremarkable.

total iris dislocation
Figure 2. Slit lamp photograph of the left eye demonstrating total iris dislocation on retroillumination.
iris remnant
Figure 3. Slit lamp photograph of the left eye showing iris remnant at 7 o’clock in the mid-anterior chamber.

Slit lamp examination of the right eye was normal. Slit lamp examination of the left eye revealed 360° of speckled conjunctival pigmentation, with focal areas of darker pigment superotemporally, temporally and inferiorly (Figure 1). The pigmented conjunctiva was freely mobile with no scleral or episcleral pigmentation and no thickening or elevation. There were no feeder vessels seen. The left cornea had diffusely scattered endothelial pigment. There was complete aniridia of the left eye (Figure 2) with a 0.5 mm round brown iris remnant at 7 o’clock in the mid-peripheral anterior chamber (Figure 3). An iris stump was also noted on gonioscopy (Figure 4). There was a well-centered posterior chamber IOL within the capsular bag with moderate posterior capsular opacification and no pseudophacodonesis.

Gonioscopic evaluation
Figure 4. Gonioscopic evaluation of the left eye showing iris stump and good visualization of ciliary processes.

Fundus exam of the right eye was normal, while examination of the left eye revealed a clump of white amorphous material noted in the inferior vitreous cavity (Figure 5).

 Fundus photo
Figure 5. Fundus photo of the left eye showing clump of white amorphous material in inferior vitreous cavity.

Anterior segment OCT was obtained to further evaluate the conjunctival pigmentation. AS-OCT revealed no invasion of the substantia propria and no apparent scarring, thinning or perforation of the underlying sclera (Figure 6).

AS-OCT
Figure 6. AS-OCT of the left eye showing conjunctival melanocytosis without invasion of the substantia propria.

What is your diagnosis?

See answer below.

Conjunctival pigmentation

Unilateral conjunctival pigmentation has a broad differential including primary or secondary acquired melanosis, conjunctival melanoma, congenital melanosis, conjunctival nevus and complexion-associated melanosis. Given that this patient’s conjunctival pigmentation was post-traumatic and not noted on prior ocular examinations, congenital melanosis was unlikely. The patient had no personal or family history of cutaneous melanoma, making suspicion for conjunctival melanoma lower although still possible. The patient’s complexion was light and the conjunctival pigmentation dark, making complexion-associated melanosis also less likely.

Rapidly progressive new-onset conjunctival pigmentation narrows the differential to acquired melanosis and pigmented malignant neoplasia. In our patient, secondary acquired melanosis was thought to be more likely given that the onset was after ocular trauma.

Conjunctival biopsy
Figure 7. Conjunctival biopsy of the left eye. Hematoxylin and eosin stain shows normal conjunctival epithelium with subepithelial melanin pigmentation and no atypical cells (a and b). On immunohistochemical staining with Sox10, a marker for uveal melanoma, there is subepithelial melanin pigmentation with an intact basement membrane and no atypical melanocytic hyperplasia (c).

Workup and management

To differentiate between acquired melanosis and conjunctival melanoma, an incisional map biopsy of the patient’s conjunctival pigmentation was performed. Histopathology revealed subepithelial melanin pigmentation with no evidence of atypical melanocytic proliferation or invasion of the substantia propria (Figure 7). She was diagnosed with post-traumatic secondary acquired melanosis. The patient was followed closely by the Lahey Hospital Cornea Service with serial photographs to monitor for any progression, and no further surgical intervention was necessary.

Discussion

Post-traumatic or post-surgical conjunctival melanosis has been reported in the literature, although many of these cases were associated with perforating scleral injury. In one case after cataract surgery, a 66-year-old woman was noted to have an elevated region of conjunctival pigmentation overlying an area of iris peaking. Surgical exploration led to identification of a superior scleral laceration and repair of a ruptured cataract wound, with pathology revealing subepithelial and substantial propria accumulations of uveal pigmentation. In another case after ocular trauma, an 83-year-old man was noted to have a conjunctival pigmented nodule surrounded by diffuse pigmentation, with histologic findings consistent with iris extrusion. A third case noted total aniridia and conjunctival melanosis after blunt ocular trauma. Further exploration of the melanosis and a cystic lump in the subconjunctival space led to identification of globe dehiscence at the limbal-scleral junction.

In our patient, blunt ocular trauma resulted in total aniridia with dislocation of the iris into the vitreous cavity. The ocular trauma and iris dislocation may have released pigment into the anterior chamber, although layering hyphema at the time of injury may have made it difficult to assess. It is unknown how soon the conjunctival pigmentation formed given the bullous subconjunctival hemorrhage immediately after the injury. Scleral injury was not suspected because the conjunctival melanosis was mobile, and there was no identifiable abnormality of the underlying sclera during surgical exploration.

To understand the mechanism of melanosis in our patient, it is helpful to review the two main outflow pathways of aqueous humor: trabecular and uveoscleral. In the trabecular outflow pathway, aqueous humor leaves the anterior chamber via the trabecular meshwork, then flows through the collector channels, Schlemm’s canal, episcleral veins, anterior ciliary and superior ophthalmic veins, and then to the cavernous sinus. In the uveoscleral pathway, aqueous humor leaves through the ciliary muscle and flows to the supraciliary and suprachoroidal spaces, and then through intact sclera along penetrating vessels and nerves such as Axenfeld nerve loops. Given that our patient had speckled conjunctival pigmentation concentrated a few millimeters posterior to the limbus, it was thought that iris pigment traveled along the uveoscleral pathway to the conjunctiva around scleral vessels and Axenfeld nerve loops.

When evaluating conjunctival melanosis, post-traumatic or post-surgical pigmentation should be considered. Understanding aqueous outflow pathways is important for identifying the origin of conjunctival pigment. There may be a macrohole with iris pigment epithelium under the conjunctiva as reported in prior case reports or a microperforation with subsequent spread of pigment. In addition, there may be release of pigment from within the eye that escapes via tiny spaces around scleral nerves and vessels, as in our patient.

On most recent follow-up, our patient had mild photophobia manageable with sunglasses. The posterior capsule opacification in the left eye was thought to help decrease the effective amount of light entering the eye despite her aniridia. We will consider an artificial iris implant in the future if her photophobia worsens. At this time, her symptoms are mild, and she prefers not to undergo surgery. She is monitored annually.