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Sarcoidosis
–
one of the most common diseases we will see
These patients are anergic.
Etiology
o
Unknown – may be due to yet unidentified infectious
agent/immunologically mediated disease
o
It
is a granulomatous lung disease from which nothing
has ever been cultured.
§
So
we have no idea what causes it.
Pathogenesis
o
Inappropriate host immunologic response (not
specifically mentioned)
o
Interactions between T cells and activated macrophages
(similar to delayed hypersensitivity seen in
mycobacterial infections) (not specifically mentioned)
o
Sequestration of T-helper cells in lung, resulting in
decreased circulating T-helpers and cutaneous anergy
(not specifically mentioned)
o
May
have “hyperactive” B-cells and increased immunoglobulin
levels
o
Systemic disease of unknown cause with noncaseating
granulomas in many tissues and organs
§
Almost always involves the lung and almost always
presents with hilar adenopathy
o
More
prevalent in women, in southeast U.S.; ten times higher
in American blacks
o
Also
seen in Scandinavian Countries
o
possibly, a delayed hypersensitivity type of response to
an antigen
Histologic Features
o
Granulomata
-
hallmark of sarcoidosis
§
Usually non-caseating/non-necrotizing
§
Dense, well-formed granulomas, often lack significant
surrounding inflammation
§
Distributed along pulmonary lymphatics in pleura, septa,
and along arteries, veins, and bronchi
§
Frequent inclusions in giant cells (Schaumann body,
Asteroid).
§
But
other diseases cause granulomas too.
·
So
sarcoidosis is a diagnosis of exclusion.
o
Interstitial Inflammation
§
Interstitial infiltrates of lymphocytes and plasma
cells
Prognosis & Natural History
o
May
develop interstitial fibrosis with “honeycombing”.
o
May
present as single episode, or chronic disease with
alternating periods of activity and remission
Clinical Features
o
Symptoms
§
May
be asymptomatic, or present with cough and dyspnea
o
Clinical Findings
§
Chest infiltrates with hilar adenopathy; radiographic
findings often more striking than physical findings
§
Variable reduction in ventilatory capacity, decrease in
diffusing capacity, and airway obstruction
Epidemiology
o
In
U.S.,
is more common in blacks than whites, and more common in
females than males
o
Typical patient is young black woman
o
In
Europe, is more common in Scandinavian countries
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