Table 1.

Comparison of cytomorphologic features in neuroendocrine tumors and mimics

	Lymphocytes/Lymphoma	Carcinoid	SCLC	LCNEC	Basaloid carcinoma
Cell arrangement	Discohesive, Pseudo-epithelioid clusters in some	Discohesive and Loosely cohesive; rosettes; associated with blood vessels	Cohesive and discohesive	Cohesive	Cohesive ± nuclear palisading at the edge of groups
Nuclei	Small, round, coarse chromatin	Small, round, monomorphism, stippled chromatin; no molding	Small, molding, pleomorphism, stippled chromatin	Larger, occasional molding	Coarse chromatin, oval/spindle cell nuclei
Nucleoli	May be prominent in immature cells/lymphoma	Inconspicuous	Inconspicuous, occasional nucleoli in “intermediate” type	Prominent	Usually absent
Cytoplasm	Scant/Absent, Basophilic	More abundant, granular, “plasmacytoid”	Scant/ Absent	More abundant, granular	More abundant, Dense
Background	Lymphoglandular bodies	Branching capillaries; Occasionally necrotic (atypical carcinoid)	Apoptotic and Necrotic	Apoptotic and Necrotic	Sometimes necrotic