Sarcoidosis and Familial Mediterranean Fever: Cause or Coincidence?
Sarcoidosis may have several associated diseases, including arterial hypertension, thyroid disorders, diabetes, lung diseases, and obesity – and now familial Mediterranean fever (FMF), an autoinflammatory disease, according to the study “Coexistence of sarcoidosis and Familial Mediterranean Fever,” from the journal Reumatología Clínica.
In the study, researchers at the Sifa University in Turkey reported the case of a 50-year-old female who exhibited simultaneous occurrence of both diseases, which posed the question of which came first? The answer is still unknown.
FMF is an autosomal recessive systemic autoimmune disorder caused by mutations in the MEFV gene. The gene enables the production of a protein called pyrin, which is produced in certain white blood cells (neutrophils, eosinophils, and monocytes), and plays a role in inflammatory processes. Mutations in the pyrin protein result in inflammation of several serous membranes including pleura, pericardium, and peritoneum with accompanying fever.
The study patient had been diagnosed with sarcoidosis a decade earlier following a lymphatic gland biopsy. She was on corticosteroid treatment for 2 years but discontinued it and was not evaluated since.
Recently, the patient was admitted to a rheumatology clinic with fatigue, recurrent fever, joint pain, and dry cough. She did not have history of FMF in her family, but claimed she had fever attacks since childhood. Her physical examination showed fever, sensitivity in both ankles and hip joints, rough lung sounds, and palpable lymphadenopathy, which was later confirmed with chest X-ray. Inflammation-related parameters were increased.
These results were compatible with stage 1 sarcoidosis, but the patient was also had mutations in the MEFV gene, suggesting a possible diagnosis of sarcoidosis and FMF. She was given anti-inflammatory NSAIDs and colchicine and three months later reported significant less abdominal pain and fever attacks.
Other cases of simultaneous occurrence of sarcoidosis and FMF have been reported, but previous studies suggested that mutations in the MEFV gene may be protective of sarcoidosis because fewer sarcoidosis patients have the mutation.
Early-onset sarcoidosis as an autoinflammatory disease, indicates that the diseases may have common causes. Still, no common connection between both diseases is known so far, and it remains to be proven whether they have common origins, or occur simply occur together as coincidence.