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PRAME expression in melanocytic lesions of the nail
Ourania Parra1, Konstantinos Linos1,2, Zhongze Li3
1Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA.
Background:
Subungual melanoma can be diagnostically challenging. We evaluated the potential of PReferentially expressed Antigen for MElanoma (PRAME) immunoreactivity for differentiating benign from malignant nail melanocytic lesions.
Methods:
Sixty cases were identified (10 invasive melanomas, 8 melanomas in situ, 14 nevi, 12 cases of lentigo, and 16 of melanocytic activation). Percentage of PRAME-positive melanocytes was evaluated as follows: 0 no staining, 1+ 1%-25%, 2+ 26%-50%, 3+ 51%-75%, and 4+ >75%. A combined score of both percentage and intensity was also evaluated.
Results:
The difference in PRAME expression between malignant and benign lesions was statistically significant (p < 0.0001). The degree of PRAME expression significantly correlated with patients' age and clinical size. When based on percentage score, 61.1% of melanomas showed a 4+ score, 16.7% showed a 3+ score, 11.1% showed a 1+ score, and 11.1% was negative; 69.0% of the benign lesions was negative, 23.8% showed a 1+ score, 4.8% showed a 2+ score, and 2.4% showed a 4+ score. When the cutoff value for malignancy decreased from 4+ to 3+, the sensitivity increased from 61.1% to 77.8%, while specificity remained 97.6%. Combined score results were similar.
Conclusions:
PRAME is a relatively sensitive and highly specific marker in differentiating benign from malignant nail melanocytic lesions. However, correlation with morphology is imperative.
Insights
PRAME expression is a sensitive and specific marker for distinguishing benign from malignant nail melanocytic lesions. Careful correlation with morphology is essential for accurate diagnosis.
Area of Science:
- Dermatopathology
- Oncology
- Immunohistochemistry
Background:
- Subungual melanoma presents diagnostic challenges.
- Distinguishing benign from malignant nail lesions is critical.
- PReferentially expressed Antigen for MElanoma (PRAME) is a potential diagnostic marker.
Purpose of the Study:
- To evaluate the utility of PRAME immunoreactivity in differentiating benign and malignant nail melanocytic lesions.
- To assess the sensitivity and specificity of PRAME as a diagnostic marker.
Main Methods:
- Sixty nail melanocytic lesions were analyzed (10 invasive melanomas, 8 melanomas in situ, 14 nevi, 12 lentigos, 16 melanocytic activations).
- PRAME-positive melanocyte percentage was scored (0, 1+, 2+, 3+, 4+).
- Combined scores of percentage and intensity were evaluated.
Main Results:
- PRAME expression significantly differed between malignant and benign lesions (p < 0.0001).
- A PRAME percentage score of 3+ increased sensitivity to 77.8% while maintaining 97.6% specificity.
- Combined scores yielded similar diagnostic performance.
Conclusions:
- PRAME is a highly specific and relatively sensitive marker for nail melanocytic lesions.
- PRAME aids in differentiating benign from malignant lesions.
- Morphological correlation remains crucial for definitive diagnosis.
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