The incidence of focal chronic inflammatory changes in human submandibular salivary glands.

Focal chronic inflammatory changes have been investigated in a series of otherwise non-diseased submandibular salivary glands obtained at necropsy from 96 subjects evenly divided by sex and decades of adult age. Two types of change were recorded: focal aggregates consisting predominantly of lymphocytes; and limited intralobular areas of parenchymal change similar to those present in obstructive sialadenitis. These were termed focal lymphocytic adenitis and focal obstructive adenitis respectively. For each gland the numbers of foci of each type were separately expressed per unit area of section examined. Focal lymphocytic adenitis, which was almost universally present throughout the series, in most cases was not associated with destructive changes in the parenchyma. It showed no simple pattern of incidence in relation to age and sex. Focal obstructive adenitis, also frequently present, showed a gradually increasing prevalence with age. Persistent foci of this type tended to form fibrous scars. These were more frequent in older decades. The increasing incidence of obstructive foci throughout adult life, plus in older age groups their persistence as focal scars, both contribute to the gradual reduction in parenchyma which is a feature of aging in the human submandibular gland.