Thymus biopsy in children with acquired immunodeficiency syndrome.

Thymic biopsy was done at the time of open lung biopsy in 11 children with acquired immunodeficiency syndrome (AIDS). Precocious involution, involution mimicking dysplasia designated as dysinvolution, and thymitis characterized by lymphomononuclear or plasmacytic infiltration, medullary lymphoid follicles, or medullary multinucleated giant cells were seen. Thymic biopsy is helpful in distinguishing AIDS from certain congenital immunodeficiency disorders. The three different types of thymic lesions may represent progression and/or different expressions of thymic epithelial injury in children with AIDS.