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Lung-nontumor

Granulomatous inflammation (non-infectious)

Sarcoidosis


Reviewers: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 22 October 2014, last major update September 2011
Copyright: (c) 2003-2014, PathologyOutlines.com, Inc.

Definition
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● Multisystemic disease of unknown origin that involves lung or bilateral hilar lymph nodes in 90% of cases

Pathophysiology
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● May be a manifestation of disordered immune regulations in genetically susceptible individiduals after exposure to environmental agents
● Increased risk with some HLA genotypes
● Increase in pulmonary T-cell CD4:CD8 ratio
● Increase in T-cell derived cytokines IL-2 and IFN-gamma
● Increase in other cytokines (IL-8, TNF, others) in microenvironment

Clinical features
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● Commonly anergy to skin test antigens, polyclonal hypergammaglobulinemia
● Presents as perihilar node involvement, diffuse pulmonary disease, pulmonary interstitial fibrosis, localized bronchial stenosis, distal bronchiectasis and atelectasis
● Age usually 20-40 years, F > M, 90% are black, rare in Chinese or southeast Asians
● 80% have elevated serum angiotensin-converting enzyme (not specific); 65% recover without further problems; 20% have permanent pulmonary loss; 3% die of pulmonary fibrosis or congestive heart failure
● A diagnosis of exclusion, since there are no specific criteria for disease; should culture and use special stains

Lungs: either no gross lesion or 1-2 cm nodules; often in bronchial submucosa, so biopsies are helpful
Lymph nodes: hilar or mediastinal lymph nodes involved in almost all cases, tonsils involved in 25% of cases; nodes are enlarged, may be calcified
Liver/spleen: gross disease in 20%, microscopic involvement in 75% of cases
Bone: X-ray changes in 20%, usually small bones of hands and feet
Skin: involvement in 30-50% with erythema nodosum; also mucus membranes
Eye: iritis or iridocyclitis in 20-50%

● Best prognosis: hilar lymphadenopathy alone
● Worst prognosis: pulmonary disease without adenopathy

Necrotizing sarcoid granulomatosis: very rare; controversial if this is a distinct form of sarcoidosis; usually affects women, often with mild or no symptoms, and excellent prognosis using steroids, immunosuppressive drugs and surgery for localized lesions; resembles tuberculosis, fungal infections or Wegener's; exclude infections with negative culture and negative histochemical stains

Micro description
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● Non-caseating epithelioid granulomas with tightly packed epithelioid cells, Langhans giant cells and lymphocytes (T cells), usually in interstitium adjacent to bronchioles and around and within vessel walls, pleura and connective tissue septa
● May also be hyalinization, diffuse interstitial fibrosis, fibrinoid necrosis, fibrosis within granulomas, intra- and extracellular inclusions
● Pleural involvement in 10%
Schaumann bodies: laminated concretions of calcium and protein
Asteroid bodies: stellate inclusions within giant cells, in 60% of granulomas
● Neither is specific for sarcoid (also seen in berylliosis)
Necrotizing sarcoid granulomatosis: extensive, vascular, non-caseating sarcoid-like granulomas invading pulmonary arteries and veins with diffuse necrosis of lung parenchyma

Micro images
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Lymphangitis distribution

           
Sarcoidosis in lymph node

Virtual slides
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Sarcoidosis

Differential Diagnosis
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Atypical mycobacteria
Berylliosis: need clinical history to differentiate
Extrinsic allergic alveolitis: loosely arranged epithelioid cells in granulomas
● Also fungi, inhalation of talc and intravenous narcotism

End of Lung-nontumor > Granulomatous inflammation (non-infectious) > Sarcoidosis


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