Table 2.

Cytomorphological differences between touch preparations, aspirate smears, and core biopsy.

Cytomorphology	Touch preparation	Aspirate smear	Core biopsy
Overall architecture	Disrupted	Disrupted	Intact
Cellularity	Variable	Variable	Variable
Cohesive cell groups	Present without surrounding stroma	Present without surrounding stroma	Present with surrounding stroma
Discohesive cells	May show artifactual clustering	Present	Infiltrative cells
Heterogeneity	Limited	High, parallels number of passes	Limited
Stroma	None to scant	None to scant	Usually present
Cystic fluid	Unsuitable	Easy to smear	Useful to identify lining epithelium
Background material	Variable, may be patchy or absent	Variable	Differenta
Blood dilution	Limited	Often present	Usually absent
Artifacts	Streaking, thick areas, and stripped cells	Air-drying, crushed cells and obscuring material	Freezing or formalin artifact (eg, cellular contraction)

^aCertain background material present in cytology slides (eg, tigroid appearance) may not be found in core biopsy sections.