Sarcoidosis

Key points

• • Sarcoidosis is a multi-system disease of unknown cause in which small clumps of immune cells, called non-caseating granulomas, form in many organs.
• • Unlike the granulomas of tuberculosis, those of sarcoidosis have no central cheesy (caseous) death, which is a key distinction under the microscope.
• • It most often affects the lungs and the lymph nodes at the roots of the lungs, seen as bilateral hilar lymphadenopathy on a chest X-ray.
• • It can also affect the skin, eyes, liver, heart and nervous system, so it can mimic many other diseases.
• • The blood may show a raised calcium level and a raised level of the enzyme angiotensin-converting enzyme (ACE), but ACE is neither sensitive nor specific and does not reliably measure the granuloma load.
• • It is commoner in young adults, often causes tiredness and breathlessness, and in many people it settles on its own.