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What is sarcoidosis?
Sarcoidosis is a multisystem granulomatous inflammatory disease that predominantly affects the lungs, but can also affect any part of the body. It is characterized by the presence of noncaseating granulomas or tiny nodules of inflamed tissue in the affected organs. These granulomas lead to altered organ architecture and disruption of normal organ function.
Sarcoidosis is very common in Ireland, and reports suggest the prevalence to be from 33 cases to 85 cases per 100 000 patients. There is no definite trigger or cause for sarcoidosis. Epidemiological studies have shown that sarcoidosis does have some genetic association as there is documented disease clustering in families. There is a 5-fold increase in your risk of disease if you have a first-degree relative with sarcoidosis.
Case reports have suggested that anti-TNF alpha medications like infliximab used for colitis or inflammatory arthritis has the potential to cause sarcoid-like inflammation.
How does sarcoidosis affect people?
There is large variability in the manner sarcoidosis can cause symptoms. Approximately 2/3rds of patients are asymptomatic or have mild disease. Here the disease is incidentally diagnosed after thoracic imaging done for unrelated reasons.
More than 90% of patients with sarcoidosis have lung involvement. Pulmonary sarcoid leads to vague chest pain, breathlessness, and a dry cough.
After lungs, sarcoidosis most commonly affects the eyes, lymph nodes and skin. It has also been known to involve the nose, muscles, heart, liver, spleen, bowel, kidneys, joints and brain.
Ocular or eye involvement causes a gritty feeling in the eye, or blurring of vision. It has been known to cause both dry eyes and red eyes when the conjunctiva is involved. Lacrimal gland hypertrophy is common but asymptomatic.
Another common way sarcoidosis affects people is with joint pains, tiredness, painful red lumps on the skin of the legs (erythema nodosum) and enlarged lymph glands. These enlarged glands may be felt in the neck, under the armpit or in the groins. Sometimes the enlarged glands occur inside the chest near the lungs, and cannot be felt, but are visible on a chest x-ray. When sarcoidosis presents in this way (Lofgren’s syndrome) the illness is usually short, with a very good outlook.
Neurosarcoidosis can be a challenging diagnosis as biopsy of the CNS is required for a definitive diagnosis. It commonly presents with unilateral or bilateral facial nerve palsy or optic nerve palsy. Neurosarcoidosis can also manifest with clinical syndromes consistent with granulomatous inflammation of either the CNS or peripheral nervous system.
Cardiac sarcoid will depend on the anatomical involvement of the heart. It can manifest in heart block, unstable broad complex arrhythmias, unexplained cardiomyopathies or be asymptomatic. Sometimes, systemic sarcoidosis symptoms can be very vague, with tiredness, mild weight loss and general aches and pains being common.
How do doctors diagnose Sarcoidosis?
Often, doctors recognise sarcoidosis from the combination of symptoms a person has. Despite classical features usually obvious on a CXR, all patients these days proceed to get tissue confirmation of noncaseating granulomas from the most accessible affected organ.
It is important to do a detailed medical history and systemic examination, as the multicentre ACCESS study (A Case Controlled Etiologic Study of Sarcoidosis) showed that one in two sarcoidosis patients have both pulmonary and extrapulmonary sarcoidosis involvement. Diagnostic testing for extrapulmonary sarcoidosis should be guided by the history and examination findings. The World Association of Sarcoidosis and Other Granulomatous Diseases (WASOG) has published helpful diagnostic criteria to help various organ-specific assessment for extrapulmonary sarcoidosis.
Investigations are decided based on the organ system affected. Commonly when the lungs are the predominant feature, a patient will get a CT scan of their lungs, after which they most likely will proceed to endoscopic sampling of their intrathoracic lymph nodes using endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA). EBUS-TBNA is essentially a day case bronchoscopy procedure taking 30 minutes to 1 hour under minimal conscious sedation. Occasionally if EBUS-TBNA is not sufficient to achieve a diagnosis, a patient will be referred for a mediastinoscopy by a cardio-thoracic surgeon. A mediastinoscopic biopsy means the mediastinal/central chest lymph nodes will be accessed using a surgical procedure called mediastinoscopy under general anaesthetic.
All patients usually get pulmonary function testing (PFTs) during their initial review and after as part of disease surveillance.
If there is extrapulmonary sarcoidosis like ocular, lymph node or skin involvement which is more easily accessible, biopsy of that affected area is considered. Note erythema nodosum; the commonest skin lesion associated with sarcoidosis is not biopsied as it usually will show nonspecific panniculitis and lacks granulomas.
Cardiac sarcoidosis commonly co-presents with systemic sarcoidosis, but rarely in isolation. After initial workup including an ECG, 24 hour holter monitor and transthoracic echo, a patient should be screened for gadolinium enhancement consistent with cardiac sarcoid on a cardiac MRI. A PET scan using FDG has good sensitivity and specificity for cardiac sarcoid in the event performing a cardiac MRI is contraindicated.
It is essential to consider alternative diagnoses if the clinical-radiological presentation does not fit with the histopathological result e.g. atypical granulomatous inflammation.
Treatment for sarcoidosis
Oral glucocorticosteroids is the mainstay of treatment of sarcoidosis. If disease is asymptomatic or only mild, treatment is not indicated. Usually steroids will be used if patient is dyspneic, poor lung function, or progressive deterioration on serial PFTs. Treatment should also be considered particularly for neurosarcoidosis, cardiac sarcoidosis, ocular sarcoidosis and hypercalcemia.
Immunosuppressant agents are used when sarcoidosis is refractory or intolerant to steroid therapy. Occasionally these agents are also used as steroid-sparing therapy in sarcoidosis.
Currently there is little evidence supporting one class of immunosuppressant agents over the other classes. After prednisolone, methotrexate or hydroxychloroquine is the next option. If this fails, either colchicine, infliximab or adalimumab can be considered.
Chronic fatigue is very common despite stable sarcoidosis and does not warrant active therapy. Neurostimulants like methylphenidate or modafinil potentially can be trialed to improve sarcoid-related fatigue on a case-by-case basis.
What is the clinical course and outlook for sarcoidosis?
Two-thirds of sarcoid patients have spontaneous resolution or improvement in disease immediately or within 2 years of initial presentation.
Rarely, sarcoidosis seems to "linger", and the patient needs to stay on treatment for a long time, even life-long. We should emphasise that this is unusual. It is not unusual, even in mild sarcoidosis, not to feel "quite yourself " for a time after diagnosis, but the clear majority of people eventually "return to normal". Most people with sarcoidosis are expected to lead a normal, healthy life.
Sarcoidosis is almost never fatal. Occasionally severe complications can manifest due to organ-threatening disease mainly in lungs, heart and brain. Organ transplantation should always be considered for significant pulmonary, cardiac, renal and liver sarcoidosis progressive despite maximal medical therapy.