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Sarcoidosis is a very rare and mysterious disease, the causes of which have not been established despite many years of research. Mainly young people suffer from it, and the acute form is the domain of women. Its symptoms are easily confused with serious diseases such as tuberculosis or malignant tumors. Despite this, it is usually only observed and not treated.
The disease is the formation of inflammatory granulomas in various organs of the body. A granuloma is an accumulation of immune system cells – mainly lymphocytes and macrophages – which, when incorrectly stimulated, transform into epithelial cells, forming clusters within various tissues of the body. What distinguishes the granulomas arising from sarcoidosis from the granulomas seen in tuberculosis is the lack of cheese formation, i.e. the presence of tissue necrosis in the center of the granuloma.
It is not known what factor causes the pathological activation of cells of the immune system, stimulating them to produce granulomas. The supposed role of mycobacteria in this process has not been scientifically confirmed. Americans, in turn, observed a higher incidence of granulomatous changes in the lungs in people exposed to airborne dust following a WTC destruction. However, none of these observations is sufficient to conclusively establish the causes of sarcoidosis.
It is quite a rare disease, occurring in Poland with the frequency of about 10 new cases per 100 people per year. Mostly young people are ill, some studies report that up to 000 percent of cases are reported in the age range of 90-10 years, and black people are up to four times more likely to suffer from the disease. According to population studies, men get sick almost twice as often as women, although the acute form – referred to as Löfgren’s syndrome – is the domain of young women.
Since sarcoidosis can be completely asymptomatic, almost half of the cases of the disease are detected by chance when a chest X-ray is taken, which reveals lung involvement in the course of the disease (occurring in over 90% of sarcoidosis cases). A typical symptom is enlargement of the lymph nodes located in the cavities of the lungs. The X-ray image shows bilateral enlargement of the pulmonary cavities, which may also be accompanied by changes in the lung parenchyma. Various variants of lung involvement are possible, sometimes the X-ray does not reveal any abnormalities, sometimes they concern only the lung parenchyma without lymph node involvement, or – in extreme cases – pulmonary fibrosis is observed. Lymphadenopathy requires differentiation from other more common diseases – mainly malignant tumors and their metastases (Hodgkin’s disease, lymphomas, lung cancer, breast cancer and many others) – and is a symptom that cannot be ignored. Patients complain of dyspnea, possibly accompanied by coughing. There is also chest pain, which is sometimes mistaken for coronary pain.
Another common site of granuloma formation that is rarely overlooked is skin, which affects about one fifth of the cases of the disease and is often the first symptom of the disease. Skin changes can be very diverse – in the acute form of the disease, the so-called erythema nodosum taking the form of painful, reddened infiltrates covering the subcutaneous tissue, most often located on the lower limbs. However, it should be remembered that erythema nodosum may occur spontaneously or accompany conditions other than sarcoidosis (e.g. tuberculosis, inflammatory bowel diseases, allergic reactions to drugs). In chronic forms of sarcoidosis, skin lesions are most often located on the face, taking the form of a papular rash or lesions resembling frostbite – the so-called rash lupus.
Eye involvement in the course of sarcoidosis is as common as skin involvement and affects about 20% of patients, but much less often, only in a few percent of cases, is the first symptom of the disease. Iritis and ciliary inflammation, uveitis, and keratoconjunctivitis may occur. In untreated patients, they can lead to glaucoma, cataracts and even blindness.
Approximately 40% of patients complain of joint pain, which may appear in various locations, but the most characteristic symptoms of the disease are ankle joints. About 1/3 of patients have enlarged lymph nodes. Cardiac involvement is rare – in about 5% of cases, but while it may be asymptomatic, it can also lead to life-threatening arrhythmias, heart failure and valvular defects. It also happens, although extremely rare, that cardiac sarcoidosis causes sudden cardiac death. Granulomas can also occur in the central nervous system, causing damage to the cranial nerves, often the facial nerve, leading to various types of hormonal disorders or granulomatous meningitis. Symptoms of the involvement of the nervous system, however, can be completely non-specific and manifest as headaches, memory problems or depression. The disease can also cause kidney damage and enlargement of the liver, spleen or salivary glands.
The symptoms of sarcoidosis could be named for a long time, because they depend on in which organ the granulomas develop and to what extent they damage it. Each patient may have a very individual constellation of symptoms. The triad of arthritis, erythema nodosum and hilum enlargement, which may be accompanied by fever, is very characteristic of the acute phase of the disease. This group of symptoms is known as Löfgren’s syndrome. About one third of patients develop nonspecific general symptoms such as weakness, increased fatigue, loss of appetite and weight loss. Additional tests show impaired lung function, anemia, elevated blood calcium levels and, more commonly, increased urinary calcium excretion. A negative tuberculin test result is characteristic of people suffering from sarcoidosis.
Given the variety of symptoms of the disease, making a diagnosis can be challenging. An additional difficulty results from the necessity to exclude other, more frequent and much more dangerous causes of the observed symptoms, such as neoplasms, tuberculosis or other diseases in the course of which non-keratinizing granulomas are observed. The final diagnosis can be made based on the characteristic constellation of symptoms and after excluding other causes of the observed abnormalities, however, the most important thing is to determine the presence of granulomas in the material collected for histopathological examination (evaluation of the collected tissues in a microscopic examination). For this purpose, bronchoscopy is most often performed, during which specimens are taken from the bronchial mucosa, as well as a biopsy of the lymph nodes and the lung. If other organs are suspected, specimens from other locations (e.g. lymph nodes, liver, salivary glands) may be taken for examination.
Although it is hard to believe after such a long discussion on the symptoms and diagnosis of sarcoidosis, even in 80% of cases within about 2 years there is a spontaneous resolution of symptoms and disease. A significant proportion of patients require only periodic observation in order to assess the degree of symptom relief and the appearance of any signs of disease progression. The indication for the initiation of treatment is the detection of the signs of progression of pulmonary lesions, which translate into deteriorating lung function, the presence of increased levels of calcium in the blood or urine, which may result in kidney damage, eye, liver, nervous system or heart damage. The first-line drugs are glucocorticoids, although if treatment with these drugs fails, other drugs are also used to suppress the abnormal activity of the immune cells that produce granulomas.
Text: lek. Paulina Jurek
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