Sarcoidosis is a chronic, multisystem disorder often of an somewhat 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. There is now quite a bit of evidence of a link between indoor fungal exposure and this autoimmune disease. 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.
Skin involvement occur in 25% of patients with sarcoidosis. The most common lesions are erythema nodosum, plaques, maculopapular eruptions and subcutaneous nodules, Similarly, eye involvement also occurs in 25% of patients and it can cause blindness. 75% of those patients have anterior uveitis and 25 to 35% have posterior uveitis.
The sarcoid arthropathy in children 5 years and older closely mimic those of JRA. The skeletal involvement in sarcoidosis has been reported with the most common sites being the hands and feet. Patients often complain of morning stiffness and pain and demonstrate limitation of motion. The bone lesions are variable size cysts, osteopenia and punch out lesions. Hepatomegaly and splenomegaly may present in 40% of all children. Parotitis occur in a minority of cases but should alert the clinician to the diagnosis. Cardiac involvement may be evident as a conduction defect on electrocardiogram. Central nervous system changes have been described, including diabetes insipidus and seizures. The most common presentations of neurosarciodosis relate to meningeal, hypothalamic and pituitary involvement. Cranial nerves involvement is commonly reported with the facial palsy as the most common. Myelopathy and peripheral neuropathy can also occur. Renal involvement is rare, however, these children are at risk for the development of nephrocalcinosis which may be asymptomatic. Serum and urinary calcium levels probably contribute to this development, but other factors are likely to be involved.
For children under 4 years of age, sarcoidosis is characterized by the clinical triad of rash, arthritis, and uveitis. Pulmonary complaints are infrequent but lung disease may develop years later. Sarcoid arthritis is persistent and nondestructive, affecting predominantly the large joints. Skeletal and eye involvement seem to be more frequent in this age group. Posterior synechia, uveitis, optic atrophy, miliary retinitis, and granuloma of the conjunctivae and optic nerve have all been described. Firm, painless, movable sarcoid nodule of the lower cul-de-sac, and rarely the bulbar conjunctiva may be present. Uveitis may be the initial and dominant manifestation of the disease. The activity of uveitis does not necessarily parallel that of the joint disease and may produce few symptoms. However, the most devastating complication is secondary glaucoma.
Biopsy remains the most important diagnostic procedure in children with sarcoidosis. Enlarged lymph nodes are an appropriate site for biopsy, but if none is present, biopsy of the scalene fat pad is most likely to reveal a lesion compatible with sarcoidosis. A conjunctival biopsy is good when typical nodules are present but the yield drops from 75% to 25% when they are absent. An enlarged parotid, skin, liver, muscle, tendon sheath, and minor salivary glands have all been biopsied. The classic biopsy finding is a noncaseating granuloma composed of epithelial cells and occasional Langerhans giant cells, lymphocyte, macrophages, and fibroblasts may surround the granuloma. Inclusion bodies are frequently observed within giant cells.
The presence of skin anergy is typical but not diagnostic of sarcoidosis. The Kvein-Siltzbach skin test consist of the intradermal injection of heat-treated suspensions of sarcoidosis spleen extract. In a positive reaction, a slowly enlarging granulomatous papule appear at the injection site, usually reaching its largest size (3-8cm) in 4-6 weeks. A biopsy then yields sarcoidosis-like lesions in 70-90% of individuals with sarcoidosis with less than 5% false positive. However, the material is not widely available, and with the use of transbronchial biopsy for diagnosis, the Kveim-Siltzbach test is no more in general use.
Hypergammaglobulinemia can occur in 75% of children with sarcoidosis. Eosinophilia is present in up to 50% of older children. Hypercalcemia is noted in less than 20% of cases, however, hypercalcuria may still be present even when serum calcium is normal. Other possible laboratory abnormalities include leukopenia and elevated sedimentation rate and alkaline phosphatase. Serum angiotensin converting enzyme levels are increased in 75% of adult patients with sarcoidosis and decrease with corticosteroid therapy or resolution of the disease. Pulmonary function tests may show restrictive, obstructive or a combination pattern.
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.
Sarcoidosis in children is usually self-limiting disease that resolves over two to three years and some patients may require no therapy. On the other hand, patients with progressive pulmonary impairment, uveitis, myocardial disease, central nervous system disease and hypercalcemia, hypercalcuria or renal impairment will need therapy as soon as the diagnosis is made. Some consider disfiguring skin lesions and arthritis as relative indications for therapy. Prednisone 1-2mg/kg per day for several weeks to be tapered to an alternate day regimen. In older children, maintenance therapy of 5-15mg every other day is often successful.
The prognosis is more favorable than in adults but is generally less favorable in symptomatic patients. Mortality in childhood sarcoidosis has been reported in 5%, however, long-term sequelae may occur in 10-20%. The average duration of symptoms at time of diagnosis is approximately 6 months. The presence of skin lesion may be a sign of poor prognosis. The degree of pulmonary involvement is not always indicative of the ultimate prognosis. In addition, pulmonary function tests correlate poorly with histologic severity, and the initial values do not predict the course of the disease.