Malignant Melanoma With Rhabdomyosarcomatous Differentiation: A Case Report

Area of Science:

• Oncology
• Dermatopathology
• Skeletal Muscle Pathology

Background:

• Malignant melanoma can exhibit divergent differentiation, a rare phenomenon where tumor cells display features of non-melanocytic cell or tissue components.
• Melanoma with rhabdomyosarcomatous differentiation is exceptionally rare, with only six adult cases previously documented in scientific literature.

Observation:

• A 75-year-old male presented with a cutaneous lesion on his right ear, initially diagnosed as malignant melanoma.
• A subsequent biopsy of a right cervical lymph node revealed changes suggestive of rhabdomyosarcoma.
• Re-evaluation of the primary skin biopsy using specific muscle markers confirmed the presence of rhabdomyosarcomatous differentiation within the malignant melanoma.

Findings:

• The study confirms a rare case of malignant melanoma exhibiting rhabdomyosarcomatous differentiation.
• Diagnostic challenges arise due to the morphologic overlap between melanoma and rhabdomyosarcoma.

Implications:

• This case underscores the importance of considering divergent differentiation in challenging melanoma diagnoses.
• Accurate diagnosis requires careful histopathologic examination and the use of specific immunohistochemical markers.
• Increased awareness of this rare melanoma subtype is crucial for appropriate patient management and treatment strategies.