Definition
A systemic granulomatous disease of unknown cause, especially
involving the lungs with resulting fibrosis, but also involving
lymph nodes, skin, liver, spleen, eyes, phalangeal bones, and
parotid glands; granulomas are composed of epithelioid and
multinucleated giant cells with little or no necrosis.
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Radiographic Appearance
(CXR)
The most common radiographic finding is bilateral hilar
lymph node enlargement, frequently with right paratracheal
enlargement, but normal lungs. Other patterns of lung abnormalities
include milia-size densities, micronodular lesions, large confluent
mass lesions that may progress to cavitation, interstitial fibrosis,
and a pattern resembling pulmonary edema and called "alveolar
sarcoid". Gallium scanning is a sensitive but unspecific method for
revealing pulmonary sarcoidosis. Gallium uptake over the orbits or
parotids is not specific either, however, a concurrently increased
uptake by the orbits, the parotids and the lungs has been considered
characteristic.
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Pathology
Sarcoidosis is a chronic, multisystem disorder of an unknown
etiology characterized by the accumulation of T-lymphocytes and
mononuclear phagocytes, nonsecreting epithelial granulomas and
derangements of the normal tissue architecture in affected organs.
All parts of the body can be affected, but the organ most affected
is the lung. Involvement of the skin, eye and lymph nodes is also
common. A variety of infectious and noninfectious agents have been
implicated, but there is no proof that any specific agent is
responsible. However, available evidence is consistent with the
concept that the disease result from an exaggerated cellular immune
response (acquired, inherited or both) to a limited class of
antigens or self antigens.
Cases of sarcoid have been described in both sexes, almost all
ages, races and geographic locations. Females appear to be slightly
more susceptible than males. There is remarkable diversity of the
prevalence of sarcoidosis among certain ethnic and racial groups. In
the United States, the majority of patients are black 10:1 to 17:1.
Blacks are often younger than whites with the disease. In Europe,
however, it affects mostly whites with higher prevalence in Sweden
and among Irish females. It is most common between the ages of
20-40, but it can occur in children and in the elderly. Although it
is rare in children, the disease is most frequent between 9 to 15
years of age. A small cluster occurs in children under age 4 years
with one half less than 1 year of age.Patients with sarcoidosis
display a mixture of depressed cell-mediated immunity and increased
humoral system activity. The absolute number of circulating T
lymphocytes is usually decreased. Levels of B lymphocytes may be
normal or increased. The presence of increased T cells in the
granulomas indicate that these are T-lymphocyte related granulomas.
Measurement of the macrophage migration inhibition factor in
patients wit sarcoidosis is further evidence of the presence of
increased numbers of activated lymphocytes. Patients are usually
anergic to skin test antigens. This deficiency of delayed
hypersensitivity is persistent and often does not change when
patients improve clinically. It has been assumed that replacement of
lymph node tissue by sarcoid granulomas produces the lymphopenia and
immune anergy dependent upon lymphocyte. Serum immunoglobulin levels
may be normal but IgG is elevated in about half the patients. The
humoral antibody response is not impaired and patients have no
increased predisposition to infection as a result of T cell
abnormalities. Serum complement, reflecting an acute phase reaction,
may be increased in active sarcoidosis but are generally normal in
subacute and chronic cases.
Sarcoidosis is often acute or subacute and self-limiting, but in
many individuals it is chronic, waxing and waning over many years.
Sarcoidosis can be occasionally discovered in a completely
asymptomatic individual, but more commonly it presents abruptly over
1 to 2 weeks or the affected individual develops symptoms such as
fever, malaise, anorexia or weight loss. These symptoms are usually
mild but in 25% of the acute cases, these complaints may be
extensive. Many patients have respiratory symptoms, including cough,
dyspnea, vague retrosternal chest discomfort. Two syndromes have
been identified in the acute group. The Lofgren's syndrome includes
the complex of erythema nodosum and x-ray findings of bilateral
hilar adenopathy, often accompanied by joint symptoms. The
Heerfordt-Waldenstrom syndrome describes individuals with fever,
parotid enlargement, anterior uveitis, and facial nerve palsy. The
insidious form develops over months and is associated usually with
respiratory complaints without constitutional symptoms. Chronic
sarcoidosis occurs most commonly in patients with the insidious
form. Ninety percent of patients with sarcoidosis have an abnormal
chest x-ray at some time during their course. Approximately 50%
develop permanent pulmonary abnormalities and 5-15% have progressive
fibrosis of the lung parenchyma. Sarcoidosis of the lung is
primarily an interstitial lung disease in which the inflammatory
process involves the alveoli, small bronchi, and small blood
vessels. These individuals typically have dyspnea, particularly with
exercise and dry cough. Hemoptysis is rare, as is production of
sputum.
Lymphadenopathy is very common in sarcoidosis. Intrathoracic
nodes are enlarged in 75 to 90% of all patients; usually this
involves the hilar nodes bilaterally, but some may only have
unilateral enlargement,the paratracheal nodes are also commonly
involved. Peripheral lymphadenopathy is very common, particularly
the cervical, axillary, epitrochlear, and inguinal nodes. The nodes
are non-tender, non-adherent, with a firm, rubbery texture. Unlike
nodes in tuberculosis, they do not ulcerate.
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Treatment:
Fortunately, many patients with sarcoidosis require no treatment.
Symptoms, after all, are usually not disabling and do tend to
disappear spontaneously.
When therapy is recommended, the main goal is to keep the lungs
and other affected body organs working and to relieve symptoms. The
disease is considered inactive once the symptoms fade. After many
years of experience with treating the disease, corticosteroid remain
the primary treatment for inflammation and granuloma formation.
Prednisone is probably the corticosteroid most often prescribed
today. There is no treatment at present to reverse the fibrosis that
might be present in advanced sarcoidosis.
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Image 1
Diagram of the stages of Sarcoidosis
http://www.nih.gov
Image 2 Chest xray showing Stage
3 sarcoidosis
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Useful Link http://blueflamingo.net/sarcoid/
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