Undifferentiated Melanoma Mimicking Pleomorphic Dermal Sarcoma: Two Additional Cases With Follow-Up Data and Short...

Area of Science:

• Dermatopathology
• Oncology
• Molecular Diagnostics

Background:

• Melanoma exhibits significant genetic variability, leading to loss of typical diagnostic features.
• Undifferentiated melanoma (UM) and dedifferentiated melanoma (DM) are challenging to distinguish from pleomorphic dermal sarcoma (PDS) due to histological atypia and lack of markers.
• UM and DM have a higher metastatic potential than PDS, making accurate differentiation critical.

Purpose of the Study:

• To highlight the diagnostic challenges posed by UM and DM.
• To emphasize the role of molecular analysis in differentiating UM/DM from PDS.
• To review literature on primary cutaneous UM and DM and discuss treatment implications.

Main Methods:

• Case presentation of two primary cutaneous UM initially misdiagnosed as PDS.
• Molecular analysis to identify specific mutations (e.g., BRAF, NRAS) for accurate classification.
• Comprehensive literature review of reported UM and DM cases.

Main Results:

• Molecular findings were key in reclassifying initially misdiagnosed UM cases.
• BRAF and NRAS mutations, common in melanoma, are rare in sarcomas, aiding differentiation.
• UM and DM demonstrate responsiveness to targeted therapies similar to conventional melanoma.

Conclusions:

• Accurate diagnosis of UM and DM is vital due to their metastatic potential.
• Molecular diagnostics are essential for distinguishing UM/DM from PDS.
• Timely diagnosis allows access to effective targeted therapies, improving patient outcomes.