Nucleolus (Nucleoli)

General: Nucleoli are composed of rRNA and proteins being assembled into immature ribosomes, and reflect the level of active protein synthesis within the cell. Reactive and reparative cells as well as malignant cells may have prominent nucleoli. Up to 10 nucleoli may be present in benign cells, though 6 is the maximum practically observed, and one or two are by far the most common.

Gross: N/A

Microscopic: Acidophilic (pink to red) staining on H & E, round to oval in benign cells, and irregular in atypical or malignant cells. Disparities among nucleolar size and shape within a single nucleus are more common in malignancy. Disparities in number of nucleoli among cells in the same tissue fragment or field are more common in malignancy. The nucleolar to nuclear ratio increases in malignancy (as with the nuclear to cytoplasmic ratio).

Differential Diagnosis:

Stains:

• Positive:
• Negative:
• Suggested, focused panel:

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Images:


Cases:

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