Synovial biopsy in the evaluation of nonrheumatic systemic diseases causing arthritis.

Systemic inflammatory diseases Sarcoidosis (Fig. 1a) Multicentric reticulohistiocytosis (Fig. 1b) CACP (campodactyly, arthropathy, coxa vara, pericarditis) (Fig. 1c) Pancreatic fat necrosis (Fig. 1d) Infections (Fig. 2a,b) Metabolic diseases Ochronosis Hemochromatosis (Fig. 3a) Amyloidosis (Fig. 3b) Scurvy (Fig. 3c) Sickle cell disease (Fig. 3d) Hemophilia Tumors Metastasic tumor (Fig. 4a) PVNS (pigmented villonodular synovitis) (Fig. 4b) Osteochondromatosis (Fig. 4c) Fibromatosis Hypertrophic pulmonary osteoarthopathy (Fig. 4d) Introduction A variety of systemic diseases not generally considered as rheumatic diseases can involve joints and can create differential diagnostic dilemmas. It is important to consider each of these possibilities because, first, they often have and require specific treatments that can prevent or ameliorate their other systemic manifestations, and second, they may not do well with the nonspecific, often immunosuppressive, therapies used for our more common diseases.