Pap stain: Medium power
Malignant cells with enlarged round to oval nuclei, often eccentrically located, binucleation, and prominent nucleoli
Pap stain: High power
Enlarged malignant cell with binucleation, characteristic of melanoma
Pap stain: High power
Malignant cells with high N:C ratios and cytoplasmic melanin pigment
Features
• Top three metastatic malignancies involving CSF
- Lung
- Breast
- Melanoma
• Multiple samples or immunocytochemistry may be needed to confirm disease
• Cellularity varies
• Malignant cells usually larger than background lymphocytes
• Usually high N:C ratio
• Cytoplasm may have melanin
• Nuclei enlarged, round to oval
• Nuclei eccentrically located
• Bi/multinucleation may be present
• Prominent nucleoli
• May have intranuclear cytoplasmic inclusions