Sarcoidosis with prevalent and severe joint localization: a case report.

Background: Sarcoidosis is a systemic granulomatous disease of unknown origin, characterized by the formation of granulomas without central necrosis. Each organ and tissue can be affected by the disease, but in most cases mainly the lungs and mediastinal lymph nodes but also skin, heart, eyes and joints are involved, the latter are mainly the metacarpophalangeal joints and bone lesions are often associated with involvement of the overlying skin. The diagnosis is often of exclusion, based on clinical and radiological suspicion, and should be confirmed by biopsy, although in each case it is necessary to exclude other possible causes of granulomatosis, including infections by mycobacteria. Here it is reported a case of particularly aggressive sarcoidosis with primitive involvement of the small joints of the hands and feet, and mediastinal lymph nodes.

Case presentation: The subject, a man, 60 years old, born in Morocco but living in Italy for many years, presented important involvement of bone structures and soft periarticular tissue, and was affected by the formation of granulomas without "caseum necrosis". The painful symptoms and the skin ulceration had led to surgical amputation of the distal phalanges of most fingers of his hands and feet, but with subsequent resurgence of lesions in acral locations after surgery. The PET/CT scan showed an amount of radiotracer in mediastinal lymph nodes, while the lymph nodes sampled by TBNA were normal and the CD4/CD8 ratio was less than 3 in the bronchoalveolar lavage. We ruled out any possible infectious cause, including mycobacterial infection (both tubercular and atypical), so the patient was treated with systemic corticosteroids, with an excellent clinical and radiological response.

Conclusions: Such a case shows how the disease can have variable expressions, without primitive lung involvement; therefore, it should be necessary to consider any possible, unpredictable localization of the disease.