Clinical Report: Unusual Pathologic Response in Cutaneous Melanoma

Overview

Revise to clarify the significance of rhabdomyoblastic differentiation in melanoma.

Background

Transdifferentiated melanoma is a rare variant characterized by phenotypic plasticity and loss of conventional melanocytic markers, complicating diagnosis and treatment. Melanoma with rhabdomyosarcomatous differentiation is particularly rare and poses unique challenges in clinical management, especially in the context of immunotherapy. Understanding these atypical presentations is crucial as neoadjuvant immunotherapy becomes more prevalent in treating melanoma.

Data Highlights

No numerical data available in the source material.

Key Findings

• The patient, a 38-year-old male, had a history of cutaneous melanoma with an isolated axillary nodal recurrence.
• Histopathological examination revealed a biphasic melanoma with a dedifferentiated component showing rhabdomyosarcomatous differentiation.
• Neoadjuvant treatment with ipilimumab and nivolumab was discontinued after two cycles due to immune-related adverse events.
• Post-treatment imaging showed a mixed metabolic response, with a complete pathological response of the melanocytic component.
• The high-grade rhabdomyoblastic component remained viable, indicating potential mechanisms of immune escape and resistance.
• Molecular profiling identified NRAS Q61R and TERT promoter mutations, suggesting a complex genetic landscape.

Clinical Implications

This case underscores the importance of recognizing atypical pathological responses in melanoma, particularly following immunotherapy. Clinicians should consider integrated histopathological and molecular assessments to guide treatment decisions and manage potential resistance mechanisms.

Conclusion

Reinforce the necessity for continued research into treatment strategies for transdifferentiated melanoma.

References

1. conexiant, Conexiant, 2023 -- Cutaneous Rhabdomyosarcoma May Mask Melanoma
2. Journal of Neuro-Oncology, Journal of Neuro-Oncology, 2009 -- High-dose chemotherapy and autologous stem cell rescue for atypical teratoid/rhabdoid tumor of the central nervous system
3. Acta Neuropathologica, Acta Neuropathologica, 2010 -- Diagnostic Challenges in Oligodendroglial Tumors Exhibiting Ganglioglioma-like Features
4. PubMed, PubMed, 2023 -- Cutaneous melanoma: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up
5. Journal of Neuro-Oncology — Emergence of Neurometastatic Merkel Cell Carcinoma: A Case Series and Review of Existing Literature
6. Neoadjuvant Nivolumab and Ipilimumab in Resectable Stage III Melanoma
7. Small but mighty: Rhabdomyoblastic melanoma
8. Cutaneous melanoma: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up - PubMed