Nipplelike protrusions in endocervical and other cells: further observations

To explore the possibility that artifact, such as externally applied mechanical stress, may contribute to the formation of nipplelike nuclear protrusions in certain predisposed cells.

The following specimens were examined for the presence and morphology of nipplelike protrusions: 100 endocervical smears, 40 bronchial specimens (brushings, washings and bronchoalveolar lavage) and fine needle aspirates of seven lactating adenomas and 10 fibroadenomas of the breast.

Nipplelike nuclear protrusions in endocervical cells were present in the majority of gynecologic endocervical smears showing abundant endocervical cells virtually regardless of menstrual status. They were observed frequently in bronchial specimens and fine needle aspirates of lactating adenoma of the breast.

It appears that nippling in cytologic preparations is a common phenomenon, particularly in benign endocervical and bronchial columnar cells, and may be found in other tissues and some neoplasms as well. The apparent nonspecificity of nippling, together with the association with other phenomena, such as nuclear "holes", stripped nuclei, nuclear distortion and cellular degeneration, strongly suggests that nippling may be largely the result of mechanical stress during smearing, brushing or other phases of specimen procurement or preparation. Nucleoli may serve as a nidus for nipple formation. Other qualities of a cell, including fragility and cytoplasmic features, may predispose it to the formation of nippling.