Melanocytic tumors have been always interesting to many clinicians and pathologists. The ones involving the conjunctiva are more challenging with the evolving modification of their classification.1
Benign conjunctival lesions of melanocytic origin can be divided into two main groups: nevi and other benign disorders such as racial pigmentation, post-inflammatory melanosis, primary acquired melanosis and pigmentation related to systemic conditions.2
Special attention has been paid to the identification and classification of primary acquired melanosis lesions, which have the potential for malignant transformation. The differentiation between such lesions and benign junctional nevi is essential.2
Our results are comparable to a large comprehensive study on conjunctival nevi in 410 consecutive patients by Shields et al.4
The age in our patients ranged from 1 to 74 years with the majority of the patients (58%) in the pediatric and adolescent age groups. The mean age at the time of surgical excision was 26 years, which is slightly younger than the mean age of 32 years at initial manifestation in their study.4
The correct clinical diagnosis of a nevus was made in 78% of the lesions, while 8% were suspected to be malignant and will be discussed in detail below.
The nevi were most commonly bulbar in 83% followed by juxtalimbal in 12%, at the caruncle in 4% and palpebral in 1%. Gerner et al in their study of 343 conjunctival nevi in Denmark described bulbar lesions in 33%, caruncle in 29%, limbal in 27% and at the eyelid margin in 1%.5
Shields et al also described a different site distribution with 72% bulbar, including the ones at or behind the limbus, 15% at the caruncle and 11% at the plica semilunaris.4
However, they described the rare occurrence of conjunctival nevi in the tarsal conjunctiva (1%) or the fornix (1%). It has been suggested that the presence of a nevus in the palpebral and forniceal region should raise the suspicion of malignancy and early biopsy.4,5
We had one palpebral lesion only in a 70-year-old, which was histopathologically proved to be a benign subepithelial nevus. Bulbar conjunctival nevi generally stop abruptly at the limbus and typically do not involve the corneal epithelium or stroma. Such an invasion would be unusual.1,4
Shields et al4
specifically looked at this feature and described rare involvement of the cornea in <1%. None of our juxtalimbal lesions showed corneal involvement.
compares our results with Shields et al.4
There was a statistically significant difference in history of enlargement of the lesion prior to surgery, pigmentation of the lesion by clinical examination, and indication for surgery. Our histopathologic distribution of the types of nevi was quite similar to other series.4,6
The commonest was compound nevus in 72%, followed by subepithelial nevus in 24%, junctional nevus in 3% and blue nevus in 1%. We found that compound nevi are the commonest in all age groups. Our three cases of junctional nevi were in the pediatric and adolescence age groups. This confirms the conclusion by Shields et al that compound and junctional nevi are usually found in younger aged group, while subepithelial and blue nevi are usually found in slightly older aged group.4
Blue nevus cells presumably originate from the incompletely migrated melanocytes of the substantia propria and are typically located deep in the nevocellular component. Although malignant cellular blue nevi have been diagnosed elsewhere, none have been reported in the conjunctiva.2
The only case of blue nevus in our series was in a 22-year-old male with a brown lesion at the caruncle and no prominent vascularization or cystic appearance. The nevus was removed for cosmetic reasons. Shields et al also demonstrated absence of cysts and feeder vessels in their four cases of blue nevi.4
Similar findings were reported by McDonnel.7
Table 2 Comparison between the results of our study and those of Shields et al.4
Zamir at al studied 63 inflamed juvenile conjunctival nevi (IJCN) in patients younger than 20 years.8
Seventy-five percent of their patients had a history of allergic disease. They suggested an association of this unique entity with allergic conjunctivitis.8
Some recent data also suggest that this association is due to the modulation of eosinophil properties by lesional fibroblasts partly through nerve growth factor.9
However, when we analyzed our patients in the pediatric and adolescence age groups (under the age of 20 years) 48% of the compound nevi where classified as IJCN and 12% (3/25) had documented vernal or allergic eye disease.
In conclusion, our findings demonstrate that the distribution of conjunctival nevi in our population is similar to other studies with compound nevus being the most common diagnosis in all age groups and bulbar lesions being the most common site. However, in our population, almost all nevi were clinically pigmented and the most common indication for surgery was cosmetic concerns. Further studies of IJCN and other conjunctival pigmented lesions including primary acquired melanosis and malignant melanoma are recommended.