Sarcoidosis
Epidemiology:
- F > M
- Blacks:whites = 10:1
- Rare in Chinese
and Southeast
Asians
Common sites:
- hilar and mediastinal
lymph nodes (almost all cases)
- any other node
in the body may be involved
- lungs
- spleen (75%)
- bone marrow
- phalangeal bones of the hands and feet
particularly
- lucent lesions radiologically
- eye and associated glands (20-50%)
- salivary glands
- skin (30-50%)
- muscle
- any tissue may be
involved:
- heart
- kidneys
- CNS
- Endocrine glands
(particularly pituitary)
Gross features:
- lungs:
- usually no gross
abnormality
- small 1-2cm
nodules may be present
- lymph nodes:
- enlarged,
discrete
- sometimes
calcified
- spleen:
- usually normal
grossly
- may be enlarged (20%)
- small nodules
occasionally
- liver:
- usually normal
grossly
- moderately
enlarged maybe
- scattered
nodules around portal triads maybe
- skin:
- variety of
appearances
- discrete
subcutaneous nodules
- erythematous plaques
- flat slightly erythematous scaly lesions similar to lupus
- eye:
- iritis or iridocyclitis
- bilateral or
unilateral
- corneal
opacities
- glaucoma
- suppression of lacrimation
Histologic features:
- noncaseating granulomas
(classic)
- tightly-clustered
epithelioid cells
- giant cells
common (Langerhans or foreign-body type)
- no central
necrosis (usually)
- fibrous rims
around granulomas in chronic cases
- eventual replacement
with hyaline fibrous scars
- Schaumann bodies often present in granulomas:
- laminated
concretions of calcium and proteins
- asteroid bodies often present in granulomas (60%):
- stellate inclusions enclosed within giant
cells
- lungs:
- distribution
along lymphatics (around bronchi and blood
vessels)
- bronchial submucosa is a high yield area (bronchoscopic
biopsies)
- alveolar
lesions may also be seen
- pleural
surfaces sometimes involved
- fibrosis and
hyalinization at varying stages
- lymph nodes
- eye:
- inflammation of lacrimal glands
Immunophenotype:
|
Marker:
|
Sensitivity:
|
Specificity:
|
|
|
|
|
Molecular features:
Other features:
- diagnosis of
exclusion
- differential of noncaseating granulomas:
- mycobacterial
- fungal
- berylliosis
- unknown etiology
- bilateral hilar lymphadenopathy or
lung involvement on CXR in 90%
- CD4 T cells are
drivers of the process
- CD4:CD8 T cell
ratio from 5:1 to 15:1 (>2.5)
- CD3:CD4 ratio
<0.31
- TH1 response
- Anergy to skin test antigens:
- Association with
HLA genotypes (class I HLA-A1 and HLA-B8)
- Clinical features:
- Unpredictable course
- 65-70% recover
with minimal or no residual manifestations
- 10-15% succumb
to progressive pulmonary fibrosis and cor pulmonale
References: