Sarcoidosis

Key points

Sarcoidosis is a chronic inflammatory disease that can involve all organs, especially the lungs, lymph nodes, eyes and skin. It is characterized by the formation of granulomas, inflamed cell masses that proliferate in the various anatomical districts.

Causes
The cause of sarcoidosis is still unknown; however, it is believed that genetic predisposition plays an important role in the triggering of the disease. Among the risk factors we cannot forget: exposure to beryllium / zirconium / aluminum, female sex, age> 50 years and infections.

Symptoms

The formation of granulomas is the hallmark of sarcoidosis. Symptoms depend on the site involved. Most variants of sarcoidosis are accompanied by: fatigue, joint pain, weight loss, fever / low-grade fever, malaise and loss of appetite.

Diagnosis
The diagnostic techniques used to ascertain sarcoidosis include: clinical observation, biopsy, bronchoscopy with broncho-alveolar lavage, radiological examination, assessment of respiratory capacity, blood tests, liver function tests.

Therapy
When necessary, it is possible to follow a drug therapy for the treatment of sarcoidosis: corticosteroids, NSAIDs, anti-rejection drugs, antimalarial drugs, inhibitory drugs of tissue necrosis factor alpha.

Definition of sarcoidosis

Sarcoidosis is a chronic multisystem disorder, with a purely inflammatory character. This disease can ideally involve all organs; however, the lungs, lymph nodes, eyes and skin appear to be the preferred targets. Sarcoidosis is characterized by the presence of particular nodular masses called granulomas: these are small agglomerates of inflamed cells that easily spread to different anatomical sites.
Although it was described as early as 1800, sarcoidosis still catches the attention of numerous researchers today, since it is not possible to trace a concrete and well-defined cause. However, it is likely that genetic predisposition, together with some environmental factors, play a major role in the triggering of the disease.

Incidence and mortality

Sarcoidosis most commonly affects people between the ages of 20 and 40; a second peak of incidence is observed in postmenopausal women over the age of 50.
Between the two sexes, women seem slightly more involved. Indeed, from the statistics reported in the magazine American Family Physician sarcoidosis appears to affect 16.5 per 100,000 healthy men and 19 per 100,000 healthy women.
Sarcoidosis is a relatively common condition:

In the United States, there are an average of 10-40 sarcoidosis patients per 100,000 healthy inhabitants. In particular, the disease mainly affects the black population.
In Denmark, there are 7-10 sarcoidosis patients per 100,000 healthy inhabitants.
In Sweden, as many as 64 people out of every 100,000 are affected by this disease: compared to all European countries, Sweden hosts the largest number of sarcoidosis patients.

We do not have reliable data on the mortality generated by sarcoidosis; however, the death rate appears to be between 5 and 10%.
Cardiac sarcoidosis (in which granulomas develop in the heart muscle) appears to be the most serious variant of the disease, which can be fatal: death occurs from left heart failure. End-stage pulmonary sarcoidosis can also lead to death from respiratory failure.

Causes and risk factors

Despite the countless etiological researches (on the causes), the triggering factor of sarcoidosis has not yet been identified with certainty. However, it appears that many patients are genetically predisposed to sarcoidosis: in these individuals, the disease appears to be triggered by bacterial or viral infections.

Hypothesis: infectious agents involved in sarcoidosis

Bacteria → Chlamydia trachomatis, Propionibacterium acnes, Borrelia burgdorferi, Mycoplasma, Mycobacterium Tuberculosis, Rickettsial
Virus → Herpes virus, Epstein-Barr virus (EBV), Retrovirus

What is certain and indisputable is that the inflamed cell clusters typical of sarcoidosis are due to the uncontrolled aggregation of some cells of the immune system.

RISK FACTORS

Although sarcoidosis does not recognize any precise cause, it is possible that some risk factors predispose a person to the disease:

Living in the Scandinavian countries: in these places there are numerous cases of sarcoidosis. From what has been said, it is possible to hypothesize that the climate and humidity of these regions constitute risk factors for sarcoidosis.
Repeated exposure, for occupational reasons, to beryllium, aluminum and zirconium can trigger granulomatous diseases clinically indistinguishable from sarcoidosis
Female gender and over 50 years of age
Familiarity: Children of parents with sarcoidosis are 5 times more exposed to the disease than those born to a healthy mother and father.

Description of the granuloma

Granulomas are the hallmark signs of symptomatic sarcoidosis. These are relatively small inflamed cell clusters with intense proliferative activity.
In general, granulomatous lesions unmistakably distinguish sarcoidosis. Upon laboratory examination, the granuloma is composed of a central area and a peripheral area:

Central zone → rich in macrophages (in different stages of activation and differentiation), Langerhans cells surrounded by CD4 lymphocytes (or T-helper) and epithelioid cells (of macrophage derivation), and giant cells with Schaumann bodies (cells with phosphatase)
Peripheral zone → rich in CD8 lymphocytes (suppressors), antigen presenting cells (macrophages) and plasma cells

Although they can appear in any anatomical location, granulomas tend to originate in the lungs and subsequently spread to areas: skin, central nervous system, eyes, kidneys, liver, spleen and lymph nodes.
Granulomas can be completely reabsorbed - therefore disappear in a more or less long period of time (months / years) without causing permanent damage - or they can create irreparable lesions. In the latter case, sarcoidosis follows a chronic course: the granulomas are unable to resorb spontaneously, therefore the affected tissue is damaged. The damage developed is proportional to the spread of the granulomas and depends on the area involved: clearly, when they are affected important organs such as the heart, sarcoidosis is extremely dangerous and, if not taken promptly, the patient can even go to death.
Recall, however, that sarcoidosis is fatal only in a small percentage of cases (5-10%).