Researchers offer a case report, overview of the differential diagnosis of pigmented lesions of the conjunctiva

(Image Credit: AdobeStock/Марина Демешко)

A team of researchers has conducted an investigation highlighting the case of a patient with conjunctival CAM and offered an overview of the differential diagnosis and management of pigmented lesions of the conjunctiva.

The research team included Margarida Ribeiro, MD; Pedro Marques-Couto, MD; Ana Gama-Castro, Teresa Dinah-Bragança, all with the Unidade Local de Saúde de São João, in Porto, Portugal, and João Barbosa-Breda, MD, PhD, professor, Research Group Ophthalmology, Department of Neurosciences, KU Leuven, Leuven, Belgium.

The research team noted a 42-year-old darkly pigmented woman presented at the emergency department in Porto, Portugal, with complaints of pruritus, foreign body sensation, and blurry vision. In addition to results that were compatible with mild dry eye disease, an anterior segment examination found dark-pigmented, ill-defined areas of the conjunctiva surrounding the temporal limbus and temporal bulbar conjunctiva in the left eye and involving the superior and inferior tarsal conjunctiva in both eyes.¹

“The patient reported no recent changes in these lesions,” the researchers wrote. “A diagnosis of complexion-associated melanosis in the palpebral conjunctiva of both eyes and primary acquired melanosis in the bulbar conjunctiva of the left eye was assumed, and the patient was placed under regular follow-up.”

The researchers noted that preservative-free tears were also recommended for the patient’s dry eye condition.

“Conjunctival pigmented lesions are a common finding during ophthalmologic evaluations,” the researchers added. “They pose a significant diagnostic challenge due to the wide array of differential diagnoses and the concern of misdiagnosing melanoma.”

Researchers further pointed out that a comprehensive clinical history and multidisciplinary evaluation are crucial in managing these cases.

Case presentation

A 42-year-old darkly pigmented woman presented at the ophthalmology emergency department with complaints of pruritus, foreign body sensation, and blurry vision for 1 week. The patient reported regular use of mascara.

During an examination by an ophthalmologist, the patient’s best-corrected visual acuity was 10/10 in the right eye (OD) and 9/10 in the left eye (OS). An anterior segment examination revealed several dark-pigmented, ill-defined areas involving the superior and inferior tarsal conjunctiva in both eyes. Additionally, one more pigmented lesion with two clock hours of extension was noticed in the bulbar conjunctiva surrounding the temporal limbus in the OS. There was also a mild punctate keratitis bilaterally. The remaining anterior segment examination was unremarkable. Evaluation of the posterior segment showed no abnormalities and intraocular pressure was within normal limits.¹

After being questioned by physicians, the patient denied any recent changes in the pigmented lesions and reported no familiar history of skin or ocular cancer.

“After a multidisciplinary discussion involving the ophthalmic oncology section of our department, a diagnosis of CAM was assumed,” the researchers wrote. “Since there was no recent evolution of the lesions, confirmatory histologic analysis was deferred and the patient continued follow-up with the ophthalmology clinic for surveillance of the lesion’s behavior, taking special care to the unilateral lesion observed in the bulbar conjunctiva in the OS, since it was not possible to exclude PAM.”

It was recommended the patient discontinue the use of mascara and preservative-free tears were provided for her dry eye condition.

Discussion

In general, lesions of the bulbar conjunctiva are more common and apparent than those in the fornix or in the tarsal conjunctiva, which can be missed by the patient, the primary care (PC) physician, and the ophthalmologist if a meticulous examination of the eyelids after eversion is not performed.¹

Melanocytic lesions that arise from the conjunctiva include nevus, CAM, PAM, and melanoma. Although nevus carries a small risk of malignant transformation, this risk is negligible in CAM.

The patient also had a unilateral pigmented lesion in the bulbar temporal conjunctiva in the OS, for which regular ophthalmologic follow-up was decided to monitor its behavior since it was not possible to exclude PAM. Therefore, even the most seemingly benign lesions require careful evaluation.

PAM is often observed in fair-skinned individuals who are middle-aged or older, but it can arise at any age and in any race. According to a series of 5002 conjunctival tumors referred to a tertiary ocular oncology center, the prevalence of PAM was found to be 12%. Moreover, a unilateral, heterogenous, patchy, golden yellow to brown mottled or dusted pigment can be seen. Its appearance regarding size and degree of pigmentation can change over time. It is frequently observed in the bulbar conjunctiva (around 90%), but can also occur in the palpebral conjunctiva, corneal epithelium, fornix, and caruncula.¹

In contrast to choroidal melanoma (the most common form of ocular melanoma), conjunctival melanoma is a very rare but also extremely serious and life-threatening condition with an estimated incidence of 0.5 per 1 million people per year and a mortality rate of 8% at 10 years of follow-up. Nearly 20% (19%) of patients with conjunctival melanoma develop metastatic disease at 10 years. Metastases to ipsilateral facial lymph nodes, brain, lung, and liver are the most common sites.

Researchers noted that it is suggested that conjunctival melanoma is linked with UV exposure and it is more common in fair-skinned individuals. Patients with conjunctival melanoma are typically middle-aged adults (5th to 6th decade of life) and present with a nodular mass arising either de novo (carrying the worst prognosis), from a nevus or PAM with atypia (most common, observed in 75%).

General features often seen at the slit lamp are elevation of the lesion, immobility, and vascularity (feeder vessels). Pigmentation is present in the vast majority of patients, but it can be also non-pigmented. The researchers noted the lesion often involves the bulbar and limbal conjunctiva but can be detected in the palpebral conjunctiva, fornix, and caruncle, and these three locations are associated with worse prognosis.¹

Conclusions

The researchers noted that melanocytic lesions of the conjunctiva can prove to be challenging, and several possible diagnoses should be considered, varying from innocuous conditions such as incidental pigment deposition and CAM to malignant and life-threatening conditions such as melanoma.

“Although the clinical features may overlap, the prognosis and management strategies are very distinctive,” they concluded. “We recommend that any conjunctival pigmented lesion noticed by the primary care physician should be referred to the ophthalmologist. Additionally, although these lesions appear most commonly in the bulbar conjunctiva, they may be hidden in the palpebral conjunctiva. Therefore, a simple gesture such as lid eversion should always be part of the basic initial evaluation of an ophthalmologist.”

Reference:

1. Ribeiro M, Marques-Couto P, Gama-Castro A, et al. (August 10, 2024) A Case Report and an Overview of the Differential Diagnosis of Pigmented Lesions of the Conjunctiva: Just a Freckle or Something to Heckle?. Cureus 16(8): e66559. doi:10.7759/cureus.66559