Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed
The initial infection with the bacterium Mycobacterium Tuberculosis is acquired via an airborne route. If the initial infection is not walled off, it may spread via bronchogenic spread with multiple pulmonary foci, lymphatic spread to more distant lymph nodes and hematogenous (miliary) spread to kidneys, lungs, liver, and meninges.
The classic finding is caseating necrosis.
The initial focus has localized air space consolidation and then spreads from the periphery via lymphatic channels to regional lymph nodes where the lymph nodes enlarge after several weeks. If the infection involutes the lesion can calcify with the Ghon focus being the calcified peripheral lung focus and the Ranke complex being the calcified peripheral lung focus and the calcified central lymph nodes. If resistance fails to develop and there is no involution the initial peripheral focus can extend to occupy an entire segment or lobe. Often there may be an associated pleural effusion. Primary TB has its peripheral foci scattered throughout the lung fields. Secondary, or reinfection, TB has 90% of its lesions in apices. The lungs may take 4 years to clear after therapy. The classic picture of primary TB is air space disease associated with hilar/mediastinal adenopathy and pleural effusion.
Section Top | Title Page
Follow us on Twitter @pedseducation and @pedsimaging
Please send us comments by filling out our Comment Form.
All contents copyright © 1992-2015 Donna M. D'Alessandro, M.D. and Michael P. D'Alessandro, M.D. and the authors. All rights reserved.
"Virtual Pediatric Hospital", the Virtual Pediatric Hospital logo, and "A digital library of pediatric information" are all Trademarks of Donna M. D'Alessandro, M.D. and Michael P. D'Alessandro, M.D.
Virtual Pediatric Hospital is funded in whole by Donna M. D'Alessandro, M.D. and Michael P. D'Alessandro, M.D. Advertising is not accepted.
Your personal information remains confidential and is not sold, leased, or given to any third party be they reliable or not.
The information contained in Virtual Pediatric Hospital is not a substitute for the medical care and advice of your physician. There may be variations in treatment that your physician may recommend based on individual facts and circumstances.