A Primary Dedifferentiated Melanoma, Masquerading as a Soft Tissue Sarcoma, Displaying BRAF p.V600E, CDKN2A, TP53 , and TERT Promoter Mutations.
Bharat Rekhi, Prachi Bapat, Abbas Agaimy et al.
✦ AI-curated · Sources linked
Case in brief
A 55-year-old woman presented with a slowly growing mass in the right popliteal region, initially diagnosed as synovial sarcoma. Imaging revealed a 6.9-cm lesion, and biopsy showed malignant cells with focal pigmentation and spindle cells in the dermis. Immunohistochemical analysis confirmed dedifferentiated melanoma, which was further supported by genetic testing revealing multiple mutations. Following wide excision, the patient developed pleural and mediastinal tumor deposits.
What made this case unusual
The case highlights a primary dedifferentiated melanoma that mimicked a soft tissue sarcoma, emphasizing the diagnostic challenges associated with such atypical presentations.
Diagnostic / clinical pearl
Clinicians should maintain a high index of suspicion for dedifferentiated melanoma in cases of soft tissue masses, particularly when immunohistochemical and genetic testing reveal atypical features.
Why it matters
This case underscores the importance of comprehensive diagnostic approaches, including immunohistochemistry and molecular testing, in accurately identifying rare melanoma variants that may be misdiagnosed.