What is the clinical evidence from this study?

Study design: Case-Control. Population: Dermatofibrosarcoma protuberans (n=42). Intervention: Fibrosarcomatous dermatofibrosarcoma protuberans (FS-DFSP) vs. Conventional dermatofibrosarcoma protuberans (C-DFSP). Primary outcome: PRAME modified H-score (mH-score) (p=0.0137).

October 3, 2024Scientific Reports9 citationsOpen Access

PRAME expression in fibrosarcomatous dermatofibrosarcoma protuberans

TIToshio IchikiKyushu University TITakamichi ItoKyushu University SSSakura ShiraishiKyushu University

Key Result

PRAME expression was significantly higher in fibrosarcomatous dermatofibrosarcoma protuberans compared to conventional dermatofibrosarcoma protuberans (mean mH-score 60.9 vs 8.9, p=0.0137).

Study Design

Type

Case-Control (n=42)

Multicenter

Structured PICO

Population

42 patients with dermatofibrosarcoma protuberans (21 with fibrosarcomatous lesions and 21 matched conventional controls) evaluated for PRAME and CD34 expression.

Exposure

Immunohistochemical analysis of PRAME and CD34 expression

Comparator

Conventional dermatofibrosarcoma protuberans (C-DFSP)

Outcome

PRAME and CD34 expression levels evaluated by H-score using QuPath bioimaging analysis softwaresurrogate

PRAME expression is significantly higher in FS-DFSP compared to C-DFSP, and combining PRAME with CD34 immunohistochemistry improves diagnostic accuracy for this rare sarcoma.

Main Result

Absolute Event Rate: 60.9% vs 8.9%

p-value: p=0.0137

Limitations

Relatively small sample size
Low event rate of FS-DFSP prevented prognostic analysis
Staining conditions for PRAME were intentionally stronger than those for melanoma, which may lead to variability between facilities
The combination of histological findings and immunohistochemistry was not considered in this research

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.

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