[Immunohistochemical markers for cytoplasmic antigens in acquired melanosis, malignant melanomas, and nevi of the conjunctiva].

BACKGROUND

Benign and malignant melanocytic lesions of the conjunctiva are difficult to differentiate histologically. At present in the ophthalmologic literature there is not known a high specific and simply applicable histological feature (tumor marker) of differentiation to identify melanocytic lesions of the conjunctiva.

METHODS

In this study 55 nevi, 15 primary acquired melanoses (stage Ia) and 54 melanomas of the conjunctiva were examined retrospectively immunhistochemically by antibodies vs. S-100 protein, and the melanoma-associated antigens HMB-45 and NKI/C3 using the labelled avidin-biotin method. 45 patients (25 female, 20 male) with malignant melanomas of the conjunctiva have been followed up clinically.

RESULTS

S-100, HMB-45 and NKI/C3 are highly significant markers to identify malignant melanomas of the conjunctiva (sensitivity: S-100: 96.4%, HMB-45: 96.3%, NKI/C3: 98.1%), whereas markers in acquired melanoses (sensitivity: 93.3%, 78.6% and 92.9%), and nevi (sensitivity: 92.9% 40.7%, 98.2%) are not. Positive tumor markers do not correlate with local recurrences or metastasis. The localization of malignant melanomas and the lymphocytic infiltration are not prognostically significant. The only significant risk factor (p = 0.0485) predicting the development of recurrence or metastasis is tumor thickness > 1.5 mm.

CONCLUSIONS

The tumor markers S-100, HMB-45 and NKI/C3 cannot differentiate reliably between benign and malignant melanocytic lesions of the conjunctiva, and positive tumor markers do not correlate with local recurrences or metastasis. The only significant risk factor (p = 0.0485) predicting the development of metastasis is tumor thickness (> 1.5 mm).