Secondary Pulmonary Tuberculosis

Secondary Tuberculosis. The initial lesion is usually a small focus of consolidation, less than 2 cm in diameter, within 1 to 2 cm of the apical pleura. Such foci are sharply circumscribed, firm, gray-white to yellow areas that have a variable amount of central caseation and peripheral fibrosis In immunocomptetent individuals, the initial parenchymal focus undergoes progressive fibrous encapsulation, leaving only fibrocalcific scars. Histologically, the active lesions show characteristic coalescent tubercles with central caseation. Tubercle bacilli can often be identified with acid-fast stains in early exudative and caseous phases of granuloma formation but are usually too few to be found in the late, fibrocalcific stages. Localized, apical, secondary pulmonary tuberculosis may heal with fibrosis either spontaneously or after therapy, or the disease may progress and extend along several different pathways. Progressive pulmonary tuberculosis may ensue in the elderly and immunosuppressed. The apical lesion exp