DQ stain: Low power
Cellular smear with clusters, small sheets and single malignant cells in a background of mucin
DQ stain: High power
Cluster of malignant cells with round to oval nuclei and vacuolated cytoplasm
Pap stain: Low power
Cluster of small uniform malignant cells in a background of abundant mucin
Pap stain: Medium power
3D cluster of small uniform cells with round to oval nuclei and abundant vacuolated cytoplasm
Pap stain: Medium power
3D clusters of malignant cells in a background of mucin
Pap stain: High power
Malignant cells with mild nuclear atypia, fine chromatin, inconspicuous nucleoli in a mucinous background
Pap stain: High power
Malignant cells with mild nuclear atypia, fine chromatin, inconspicuous nucleoli in a mucinous background
Pap stain: High power
Malignant cells with mild nuclear atypia, fine chromatin, inconspicuous nucleoli in a mucinous background. Note mitotic figure (significant atypia and mitotic figures are uncommon)
Pap stain: High power
Malignant cells with mild nuclear atypia, fine chromatin, and inconspicuous nucleoli
Features
• Pure mucinous carcinoma is rare (<2%)
• Often occurs in postmenopausal women
• Has favorable prognosis
• Well-circumscribed with soft gelatinous consistency
• More commonly seen as mixed component with ductal carcinoma
• FNA typically cannot exclude ductal component, so mucinous carcinoma is usually not a FNA diagnosis
• Cellular smears
• Nests of tumor cells floating in mucin
• 3D clusters, sheets, single cells
• Bland uniform cells
• May have mild atypia
• Intracellular cytoplasmic mucin vacuoles
• May have neuroendocrine differentiation
• Round to oval, uniform nuclei
• May have eccentric nuclei
• Fine chromatin
• Small inconspicuous nucleoli
• Abundant extracellular mucin
• Necrosis/mitosis rare
• No myoepithlial cells
• May have branching vessels
• Duane, GB et al. Acta Cytol. 1987 Nov-Dec;31(6):742-50.