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Updated: Jan 21, 2026
A Non-invasive Way to Isolate and Phenotype Cells from the Conjunctiva
Published on: July 5, 2017
Melanocytoma of the Conjunctiva: Clinicopathologic Features of Three Cases
Martina C Herwig-Carl1, Karin U Loeffler1, Hans E Grossniklaus2,3
1Department of Ophthalmology, University of Bonn, Bonn, Germany.
Background:
Melanocytoma (magnocellular nevus) is a jet-black benign lesion histologically composed of polygonal tumor cells with small, inconspicuous nuclei and abundant cytoplasm. Melanocytomas in general are rare. Most cases occur in the optic nerve head. Conjunctival melanocytoma (magnocellular nevus) is extremely rare, and only 3 lesions of the ocular surface have been reported.
Objectives:
To describe the clinical and histological spectrum of conjunctival melanocytoma and discuss differential diagnoses of this rare lesion.
Method:
Four heavily pigmented conjunctival lesions were excised for slight tumor growth and histologically processed. The specimens were routinely stained with hematoxylin and eosin and periodic acid-Schiff. Sections were bleached and immunohistochemical stains were performed for CD68, HMB-45, S100, melanin, and Ki-67.
Results:
Histological examination revealed findings of a conjunctival melanocytoma in 3 cases. The fourth case was diagnosed histologically as a combined melanocytic lesion with a compound nevus and an inverted type A nevus. None of the lesions exhibited transition towards malignancy. The differential diagnoses included conjunctival melanoma, granular cell nevus, compound nevus with reactive changes, and blue nevus.
Conclusions:
Conjunctival melanocytic lesions suspicious for melanocytoma should be bleached to evaluate their cytologic features. CD68 can be helpful in identifying heavily pigmented melanomacrophages which may mimic a melanocytoma. As conjunctival melanocytomas are extremely rare, their pathogenesis may be different from that of other conjunctival nevi.
Insights
Conjunctival melanocytoma, an extremely rare benign lesion, was studied in four cases. Histological analysis confirmed three melanocytomas, highlighting the importance of bleaching and immunohistochemistry for accurate diagnosis.
Area of Science:
- Ophthalmology
- Dermatopathology
- Oncology
Background:
- Melanocytoma (magnocellular nevus) is a rare, jet-black benign lesion, typically found on the optic nerve head.
- Conjunctival melanocytoma, affecting the ocular surface, is exceptionally rare, with limited prior reports.
Purpose of the Study:
- To delineate the clinical and histological characteristics of conjunctival melanocytoma.
- To explore the differential diagnoses for this rare ocular surface lesion.
Main Methods:
- Four heavily pigmented conjunctival lesions underwent surgical excision and histological processing.
- Standard staining (H&E, PAS) and special stains (CD68, HMB-45, S100, melanin, Ki-67) were employed, including bleaching.
Main Results:
- Histology confirmed conjunctival melanocytoma in three cases; the fourth was a combined melanocytic nevus.
- No evidence of malignancy was observed in any of the examined lesions.
- Differential diagnoses considered included conjunctival melanoma and various nevi.
Conclusions:
- Bleaching is crucial for evaluating cytologic features in conjunctival melanocytic lesions suspected to be melanocytoma.
- CD68 staining aids in differentiating melanocytoma from pigmented melanomacrophages.
- The unique rarity of conjunctival melanocytomas suggests potentially distinct pathogenetic mechanisms compared to other conjunctival nevi.
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