ABSTRACT
A granuloma is a focal collection of inflammatory cells that include
mononuclear cells, macrophages, and giant cells along with a number of
lymphocytes, plasma cells, and fibroblasts. Granulomatous reactions may
be classified functionally into two major categories (1). The first group
consists of lesions characterized by delayed-type hypersensitivity, antigen-
specific response. These granulomas have a high rate of cell turnover, are very active lesions, and are seen in tuberculosis, sarcoidosis, hypersensiti-
vity pneumonitis, and schistosomiasis. The second type is a foreign body
granuloma that lacks an antigen-specific response and often is an inactive,
minimally destructive lesion. These low-turnover granulomas are seen in
berylliosis, where the offending agent is inanimate and inert. The composi-
tion of the causative irritant and its degradability and immunogenecity are
decisive factors in the development of a granuloma (2).
