A Simon focus is a tuberculosis (TB) nodule that can form in the apex of the lung when a primary TB infection elsewhere in the body spreads to the lung apex via the bloodstream.[1] Simon focus nodules are often calcified.[1]
The initial lesion is usually a small focus of consolidation, less than 2cm in diameter and located within 1 to 2 cm of the apical pleura.[2] In adolescence, Simon foci may become reactivated and develop into Assmann foci.[3] Such foci are sharply circumscribed, firm, gray-white to yellow areas that have a variable amount of central caseation and peripheral fibrosis.[citation needed]
References
edit- ^ a b Leung, AN (February 1999). "Pulmonary tuberculosis: the essentials". Radiology. 210 (2): 307–22. doi:10.1148/radiology.210.2.r99ja34307. PMID 10207408.
- ^ Robbins Basic Pathology (8th ed.). Elsevier. 2007. ISBN 978-1-4160-2973-1.
- ^ "Assmann focus". Medicine.academic.ru. Retrieved 4 March 2015.
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