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PRAME expression in melanocytic lesions of the conjunctiva
Daja Šekoranja1, Gregor Hawlina2, Jože Pižem1
1Institute of Pathology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
Aims:
PRAME (PReferentially expressed Antigen in MElanoma) is a tumour-associated antigen that is preferentially strongly expressed in most cutaneous melanomas but not or only focally in naevi. Our aim was to evaluate PRAME expression in melanocytic lesions of the conjunctiva.
Methods And Results:
Surgical specimens of 114 conjunctival melanocytic naevi of different types (including 67 common, 25 combined deep penetrating and 21 inflamed juvenile naevi), 30 invasive melanomas, 10 in-situ melanomas, 23 primary acquired melanoses (PAM) without atypia and 11 PAM with atypia were analysed for PRAME expression by immunohistochemistry. Nuclear positivity for PRAME in melanocytes was assessed as the percentage of positive nuclei: negative (0%), 1+ (1-25%), 2+ (26-50%), 3+ (51-75%) and 4+ (> 75%). In 113 of 114 conjunctival melanocytic naevi, PRAME was either completely negative or focally 1+ positive. Diffuse 4+ PRAME expression was identified in 17 of 30 (57%) invasive melanomas, seven of 10 (70%) in-situ melanomas, four of five (80%) PAM with severe atypia, none of three PAM with moderate atypia, none of three PAM with mild atypia, one of 23 (4%) PAM without atypia and none of 114 naevi. Diffuse 4+ PRAME expression in invasive melanomas correlated with a higher mitotic count but was not related to age and gender of the patients, Breslow thickness, location or mutational status.
Conclusion:
Diffuse 4+ PRAME positivity is highly specific for malignant conjunctival melanocytic lesions. PRAME is therefore a useful ancillary marker to support the diagnosis of a suspected conjunctival melanoma.
Insights
PRAME (PReferentially expressed Antigen in MElanoma) is highly specific for malignant conjunctival melanoma. This marker aids in differentiating cancerous lesions from benign ones, improving diagnostic accuracy.
Area of Science:
- Ophthalmology
- Dermatopathology
- Oncology
Background:
- PRAME (PReferentially expressed Antigen in MElanoma) is a tumor-associated antigen.
- It shows strong expression in most cutaneous melanomas but is absent or focal in nevi.
- Its utility in conjunctival lesions requires evaluation.
Purpose of the Study:
- To assess PRAME expression in various conjunctival melanocytic lesions.
- To determine if PRAME can differentiate benign from malignant conjunctival melanomas.
Main Methods:
- Immunohistochemistry was used to analyze PRAME expression in 114 conjunctival melanocytic nevi and 34 melanomas (invasive and in situ).
- Primary acquired melanoses (PAM) with and without atypia were also included.
- PRAME positivity was quantified by nuclear staining percentage.
Main Results:
- 113 out of 114 conjunctival nevi showed negative or focal PRAME expression.
- Diffuse 4+ PRAME expression was found in 57% of invasive melanomas and 70% of in-situ melanomas.
- PRAME expression was significantly higher in malignant lesions and PAM with severe atypia compared to benign nevi.
Conclusions:
- Diffuse 4+ PRAME positivity is highly specific for malignant conjunctival melanocytic lesions.
- PRAME serves as a valuable ancillary marker for diagnosing suspected conjunctival melanoma.
- This finding can improve the accuracy of differentiating benign from malignant conjunctival tumors.
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