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Published on: March 18, 2014
PRAME expression in fibrosarcomatous dermatofibrosarcoma protuberans
Toshio Ichiki1,2, Takamichi Ito2, Sakura Shiraishi1,3
1Department of Anatomic Pathology, Pathological Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Abstract:
PRAME (PReferentially expressed Antigen in MElanoma) was first identified as a malignant melanoma-specific antigen. Recently, a few cases of fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP) were shown to have positivity for PRAME, while conventional dermatofibrosarcoma protuberans (C-DFSP) was negative. Because PRAME may be of diagnostic utility in FS-DFSP and is raising expectations as a new immunotherapy target, we examined the positivity of PRAME in FS-DFSP. Twenty-one cases of FS-DFSP and age/sex/location-matched cases of C-DFSP as a control group were examined by immunohistochemistry for CD34 and PRAME. The results were then evaluated by H-score, which was objectively and semi-quantitatively calculated using the open-source bioimaging analysis software QuPath. The results revealed that the PRAME H-score in FS-DFSP was significantly higher than that in C-DFSP (p = 0.0137). As for CD34, the H-score in FS-DFSP was significantly lower than that in C-DFSP (p < 0.001). Using these two immunohistochemical analyses in combination, the sensitivity and specificity for the diagnosis of FS-DFSP were 86% and 90%, respectively. Double staining of CD34 and PRAME revealed that PRAME-positive and CD34-positive areas did not overlap. This is the largest study to examine PRAME expression in FS-DFSP, and it confirmed the usefulness of PRAME in diagnosing this condition.
Insights
PRAME (PReferentially expressed Antigen in MElanoma) is a useful diagnostic marker for fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP). This study found PRAME expression is significantly higher in FS-DFSP than conventional DFSP, aiding in diagnosis.
Area of Science:
- Oncology
- Dermatopathology
- Immunohistochemistry
Background:
- PRAME (PReferentially expressed Antigen in MElanoma) is a tumor antigen initially identified in melanoma.
- Previous studies suggest PRAME expression may differentiate fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP) from conventional DFSP (C-DFSP).
Purpose of the Study:
- To investigate the diagnostic utility of PRAME expression in FS-DFSP.
- To compare PRAME and CD34 expression in FS-DFSP versus C-DFSP.
- To evaluate PRAME as a potential immunotherapy target in FS-DFSP.
Main Methods:
- Immunohistochemistry was performed on 21 FS-DFSP cases and matched C-DFSP controls.
- Expression levels of PRAME and CD34 were quantified using H-score with QuPath software.
- Combined analysis of PRAME and CD34 expression was used to assess diagnostic accuracy.
Main Results:
- PRAME H-scores were significantly higher in FS-DFSP compared to C-DFSP (p=0.0137).
- CD34 H-scores were significantly lower in FS-DFSP compared to C-DFSP (p<0.001).
- Combined PRAME and CD34 immunohistochemistry achieved 86% sensitivity and 90% specificity for FS-DFSP diagnosis.
Conclusions:
- PRAME is a valuable immunohistochemical marker for distinguishing FS-DFSP from C-DFSP.
- The inverse relationship between PRAME and CD34 expression aids in differential diagnosis.
- This study confirms the diagnostic utility of PRAME in FS-DFSP and supports its potential as an immunotherapy target.
