Melanoma to rhabdomyosarcoma plasticity in the setting of immunotherapy.
Andrew D Knight, Emily J Robitschek, Jia-Ren Lin et al.
✦ AI-curated · Sources linked
Case in brief
A 70-year-old man with metastatic melanoma developed a distinct pleomorphic rhabdomyosarcoma during treatment with immune checkpoint inhibitors, including pembrolizumab and ipilimumab. Analysis of tumor samples revealed shared driver mutations and unique mutations in the emerging RMS, indicating phenotypic plasticity. The case highlights the complexity of tumor evolution under immunotherapy pressure.
What made this case unusual
The emergence of pleomorphic rhabdomyosarcoma from metastatic melanoma during immunotherapy represents a notable instance of phenotypic plasticity.
Diagnostic / clinical pearl
Clinicians should be aware that metastatic melanoma can transdifferentiate into other histologically distinct tumors, such as rhabdomyosarcoma, under the selective pressure of immunotherapy.
Why it matters
Understanding the mechanisms of phenotypic plasticity in tumors can inform treatment strategies and highlight the challenges of acquired resistance to immunotherapy.