Conjunctival Nevus

Authors: 
Moshe Shapira, MD, and Eliezer Merksamer, MD
Maccabi Health Services, Nave-Shaanan Clinic, Haifa, Israel

Citation: 
Shapira M, Merksamer E. Conjunctival nevus. Consultant. 2018;58(8):217-218.

A 17-year-old black girl, a new immigrant from Ethiopia to Israel, presented for a routine checkup. Her medical history was unremarkable, and physical examination findings were normal, except for an oval, pigmented lesion measuring 2.0 × 3.5 mm on the bulbar conjunctiva of her left eye (Figure). The girl reported having no ocular symptoms (eg, pain, itching, tearing, photophobia) or systemic symptoms.

Figure: An oval, pigmented lesion was present on the bulbar conjunctiva of the girl’s left eye.

The patient did not remember at what age the eye lesion had appeared, nor whether the lesion had grown in recent years.

Ophthalmologic examination revealed a visual acuity of 6/6 and a sessile, black-brown, elevated lesion at the inferotemporal interpalpebral conjunctiva close to the limbus. The lesion moved freely with the conjunctiva and was not attached to the sclera. Intraocular pressure, and fundoscopy findings were normal.

The clinical ophthalmologic diagnosis was conjunctival nevus, and twice-annual follow-up visits were recommended. Ocular computed tomography (OCT) was not done.

NEXT: Discussion

Discussion. Proliferation of melanocytes are the most common tumors of the conjunctiva, accounting for up to 53% of conjunctival neoplasms; of these melanocytic proliferations, 28% are conjunctival nevi.¹ Conjunctival nevi are most common in the young white population and are less frequent in black, Asian, and Hispanic populations.² The incidence is 1.2 in 10 million people per year in all races, with equal sex distribution.³

The nevi appear in the conjunctiva as flat or mildly raised circumscribed macules or papules. In children, they usually manifest without pigmentation but become pigmented after puberty or pregnancy.¹ Most conjunctival nevi (72%) are located in the bulbar conjunctiva, mainly in the temporal and nasal quadrant, with a minority located in the superior and inferior quadrants. Other locations include the caruncle (15%), plica semilunaris (11%), fornix (1%), tarsus (1%), and cornea (<1%).² Most conjunctival nevi are brown; the rest are tan or nonpigmented.²

The most frequent histologic type of conjunctival nevi is the compound nevus (72%), followed by subepithelial nevus (24%), junctional nevus (3%), and blue nevus (1%).² Microscopically, they may appear as intraepithelial nests of oval cells (type A melanocytes), sheets of oval to cuboidal cells (type B melanocytes), and spindle-like cells in the subepithelium (type C melanocytes).^1,2

Compound nevi consist of type A or less frequently type B melanocytes, and a characteristic feature of this type of nevus is the formation of cysts by protrusions of the epithelium into the lamina propria.¹

Junctional nevi consist of nested type A and B melanocytes and sometimes by lentiginous proliferations of the cells confined to the epithelium. This type of nevus may show mitotic activity,¹ with less formation of cysts compared with compound and subepithelial nevi.^1,2

Subepithelial conjunctival nevi share the same histologic features as dermal nevi and appear more frequently in adults, with type B and C melanocytes in the substantia propria.^1,3 Cyst formation is less frequent compared with compound nevi.

Approximately 33% of conjunctival nevi show feeder and intrinsic vasculature. Shields and colleagues² found that, in 11 years of follow-up of 149 patients with conjunctival nevi, the color was stable in 87% of cases, darkened in 5%, and lightened in 8%. The lesion size was stable in 92% of cases, larger in 7%, and smaller in 1%.

Compound and junctional nevi are more frequent in children and younger adults, while subepithelial and blue nevi are usually found in older groups.³

The differential diagnosis of a conjunctival nevus includes racial melanosis, which manifests as benign, bilateral, flat conjunctival pigmentation, usually affecting darkly pigmented persons.⁴ Primary acquired melanosis (PAM) is a flat pigmentation of the conjunctiva, appears mainly in the white population, is unilateral, and is located near the limbus. PAM has the potential to evolve to melanoma when atypical melanocytes are observed.⁴ Ocular melanocytosis is a benign congenital pigmentary lesion involving the sclera.⁴

Conjunctival melanoma is a malignant pigmentary elevated lesion that may affect any portion of the conjunctiva; it usually appears in older white persons, is unilateral, and develops from a preexisting pigmentary lesion of the conjunctiva such as PAM or nevus and rarely develops de novo.⁴ Presentations suspicious for a melanoma from a conjunctival nevus that call for an excisional biopsy include the following: rapid enlargement; changes in color and shape with indistinct margins; unusual location in the conjunctiva, such as the fornix; extension into the cornea; attachment to the sclera; presence of multiple, large feeding vessels on slit-lamp examination; and recurrence after biopsy.^1,5

OCT is a valuable tool in predicting the benign or malignant nature of the conjunctival lesion by detecting cysts and intralesional vessel morphology.⁵

Especially in children, a sudden change in size and color of a conjunctival nevus to orange or pink may indicate an inflamed juvenile nevus associated with allergic conjunctivitis via modulation of eosinophils by lesional fibroblasts through nerve growth factor, and by the fact that malignant melanoma is rare in this age group.^3,5

The natural history of conjunctival nevi is benign, and only a minority show changes of pigmentation (13%) and size (8%).²

The main indication for excision of a conjunctival nevus, according to Alkatan and colleagues,³ is cosmetic (38%), followed by no specific reason (33%), an increase in size (21%), and suspicion of malignancy and/or change in color (8%).

Clinical follow-up once or twice annually, with photographs taken at every visit, is indicated if the conjunctival nevus is stable and does not show signs suspicious for malignancy, but in suspicious presentations, an excisional biopsy is indicated.⁴ The risk of malignant transformation for a conjunctival nevus to conjunctival melanoma is very small (1%).^1,2 

References:

1. Zembowicz A, Mandal RV, Choopong P. Melanocytic lesions of the conjunctiva. Arch Pathol Lab Med. 2010;134(12):1785-1792.
2. Shields CL, Fasiuddin AF, Mashayekhi A, Shields JA. Conjunctival nevi: clinical features and natural course in 410 consecutive patients. Arch Ophthalmol. 2004;122(2):167-175.
3. Alkatan HM, Al-Arfaj KM, Maktabi A. Conjunctival nevi: clinical and histopathologic features in a Saudi population. Ann Saudi Med. 2010;30(4):306-312.
4. Rayward O, Moreno-Martín P, Vallejo-Garcia JL, Vano-Galvan S. Ophthaproblem: can you identify this condition? Can Fam Physician. 2011;57(10):1157-1160.
5. Tóth-Molnár E, Vizvári E, Skribek Á, Vörös A. Giant conjunctival nevus in a 12-year-old child. Case Rep Ophthalmol Med. 2017;2017:8414352.