Frequency of "blue bodies" in pulmonary cytology specimens

To determine the frequency of occurrence of "blue bodies" (BBs), 2,010 pulmonary cytology specimens (1,403 sputum and 607 bronchial specimens) from 1985 were reviewed. The smears were examined microscopically by transmitted and polarized light. BBs were extracellular structures, occurring most commonly in clusters but sometimes conglomerated. With Papanicolaou stain, they had a characteristic birefringent laminated brown core and a nonbirefringent blue rim. Chemical microanalysis and energy-dispersive x-ray analysis revealed that their chemical composition was calcium carbonate. A total of 233 specimens contained BBs, with a frequency of 10.5% in bronchial specimens and 12% in sputum. Only 8.6% of the BBs had co-existent pulmonary malignancy. We concluded that BBs were common structures in pulmonary cytology and were not associated with pulmonary malignancy or pulmonary fibrosis in our series. They must be distinguished from contaminants, staining artifacts, and parasitic ova.