Common Features of Adenocarcinoma

• Most common cause of malignant effusion;

• Foreign groups of cells, glandular acini, cell balls (morulas) and papillae, smooth community borders;

• Increased N/C ratio;

• Enlarged nuclei, pleomorphism, hyperchromasia and irregular nuclear membrane;

• Large nucleoli;

• Secretory vacuoles or epithelial mucin;

• Three dimensional aggregates

Breast Cancer

• Often uniform, cannonballs (ductal carcinoma), small cells in single or chains (lobular);

• Intra-cytoplasm lumens, often cytoplasmic neutral lipid;

• Often fine chromatin and dense cytoplasm.

Lung Cancer

• Small cell carcinoma;

• Non-small cell carcinoma, may show combined glandular and squamous differentiation.

Kidney Cancer

• Acinar or papillary groups;

• Clear cytoplasm or glandular center in cytoplasm with a clear periphery;

• Cytoplasm is rich in glycogen and lipid, not mucin,

Stomach Cancer

• Often isolated cells, but may show papillae or acini;

• Large columnar cells or individual signet ring cells;

• Often contain cytoplasmic mucin.

Colorectal Cancer

• Exfoliate cells in papillary or acinar aggregates;

• Large tall columnar cells, nuclear palisading, apical cytoplasmic density;

• Most mucin positive.

Pancreaticobiliary Cancer

• May form round clusters or chains with nuclear molding;

• May be mucinous or serous;

• Often contain a very well-differentiated component, even in poorly differentiated tumors.

Ovarian Cancer

• Often large, irregular, transparent clusters;

• Often large, pleomorphic cells with large degenerative vacuoles;

• Often large nucleoli;

• Psammoma bodies;

• Three types: mucinous, serous, and endometrioid. May be mixed.

Pseudomyxoma Peritonei

• Very thick mucin;

• Sparse tumor cells in cohesive sheets;

• Well-differentiated, bland and tall columnar cells with large mucin vacuoles.

Liver Cancer

• Usually associated with ascites;

• Tumor cells may be sparse;

• Bile production.

Squamous Cell Cancer

• Not often in effusion;

• Non-keratinized SCC more often than keratinized SCC;

• Frequently vacuolated, resemble adenocarcinoma;

• Tumor cells can be singly or in cluster;

• Thick, dense cytoplasm with very distinct cell borders;

• Tends to be round in fluid. May show abnormal shapes, snake, tadpoles;

• Orange or eosinophilic cytoplasm;

• May show keratin pearls. Mucin negative.

Small Cell Carcinoma

• May be single, in cluster or chain;

• Small to medium size with scant cytoplasm and inconspicuous nucleoli;

• Molding;

• Round, angular or spindle cells.

Lymphoma/Leukemia

• No aggregates;

• May show nuclear atypia.

Melanoma

• Mostly single;

• Relatively large cells with large eccentrically located nuclei;

• Intranuclear cytoplasmic invaginations; prominent nucleoli;

• Melanin pigment.

Carcinoid Tumors

• monotonous small round cells, single,  in chains or in loose clusters;

• Cells may be round up with molding;

• Scant cytoplasm;

• Single nucleus with salt and pepper chromatin.

Germonoma

• Flat sheets, small clusters, or singly;

• Cells are large, polyhedral;

• Cytoplasm is clear, pale or foamy and contains glycogen;

• Nuclei are large, vesicular with prominent nucleoli;

• Lymphocyte background;

• Multinucleated giant cells may be present.

Sarcoma

• Sarcoma may develop effusion, but tumor cells are rarely in the fluid.

Reference

• The art and science of cytopathology. Richard M Demay, MD. 1996