Electron microscopy of a nevus cell aggregate associated with an axillary lymph node

Area of Science:

• Dermatopathology
• Surgical Pathology
• Oncology

Background:

• The cellular origin of nevus cell aggregates (NCAs) remains debated, with theories suggesting either nevus cells or glomus cells.
• Investigating the precise nature of NCAs is crucial for understanding potential origins of melanomas.

Observation:

• An NCA was isolated from the capsule of a lymph node in a breast cancer patient.
• The NCA was prepared from a paraffin block for detailed electron microscopic examination.

Findings:

• Ultrastructural analysis revealed uniform, round cells with indented nuclei, dispersed chromatin, and cytoplasmic fibrils.
• The presence of mature melanosomes and resemblance to cutaneous intradermal nevus cells strongly supports a nevus cell origin.
• The observed cells showed no characteristics typical of glomus cells.

Implications:

• These findings challenge the glomus cell theory for NCA formation.
• The study suggests that NCAs found in lymph nodes may represent a noncutaneous source for the development of malignant melanomas.
• This has significant implications for cancer research and diagnostic pathology.