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PRAME Expression as Helpful Immunohistochemical Marker in Rhabdoid Melanoma
Valerie Glutsch1, Marion Wobser1, Bastian Schilling1
1Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, 97080 Würzburg, Germany.
Background:
Rhabdoid melanoma is a rare variant of malignant melanoma with characteristic cytomorphologic features. Due to the potential loss of conventional melanocytic markers, histopathologic diagnosis is often challenging. We hypothesize that immunostaining for PReferentially expressed Antigen in MElanoma (PRAME) might have the potential to uncover the melanocytic origin of these dedifferentiated tumors.
Methods:
Four cases of rhabdoid primary melanomas were assessed by immunohistochemistry for expression of PRAME and conventional melanocytic markers. Immunohistochemical expression patterns were analyzed in the rhabdoid primaries and, if available, associated metastases.
Results:
All four cases of rhabdoid primary melanomas showed a strong nuclear positivity for PRAME, while the expression of conventional melanocytic markers S100, MART-1, SOX-10 and HMB-45 was variable between the analyzed cases.
Conclusions:
In summary, we report four cases of rhabdoid primary melanoma with high to intermediate expression of PRAME despite the partial and variable loss of other melanocytic markers. Hence, PRAME might facilitate the recognition of this highly aggressive entity to avoid misdiagnosis due to histopathologic pitfalls.
Insights
Diagnosing rhabdoid melanoma is challenging due to loss of markers. PReferentially expressed Antigen in MElanoma (PRAME) shows strong positivity, aiding in identifying this aggressive cancer and preventing misdiagnosis.
Area of Science:
- Oncology
- Dermatopathology
- Immunohistochemistry
Background:
- Rhabdoid melanoma is a rare malignant melanoma variant.
- Histopathologic diagnosis is challenging due to loss of conventional melanocytic markers.
- PReferentially expressed Antigen in MElanoma (PRAME) is investigated as a potential diagnostic marker.
Purpose of the Study:
- To evaluate the utility of PRAME immunostaining in diagnosing rhabdoid melanoma.
- To assess PRAME expression in relation to conventional melanocytic markers.
Main Methods:
- Immunohistochemistry was performed on four rhabdoid primary melanoma cases.
- Expression of PRAME and conventional markers (S100, MART-1, SOX-10, HMB-45) was analyzed.
- Expression patterns were compared between primary tumors and metastases.
Main Results:
- All four rhabdoid melanomas exhibited strong nuclear PRAME positivity.
- Expression of conventional melanocytic markers was variable.
- PRAME expression remained consistent despite loss of other markers.
Conclusions:
- PRAME is a reliable marker for identifying rhabdoid melanoma.
- PRAME can aid in diagnosing this aggressive entity, even with loss of other markers.
- This finding helps avoid misdiagnosis in challenging histopathologic cases.
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