Systemic Lupus Erythematosus (SLE): This is a chronic autoimmune disease that can present with a wide range of symptoms, including fever, polyarthralgia (multiple joint pains), and anasarca (generalized edema), which are common manifestations of SLE due to its systemic nature affecting multiple organ systems.

Rheumatoid Arthritis (RA): While RA primarily causes joint symptoms, it can also lead to systemic symptoms like fever and, less commonly, generalized edema, especially in more severe or untreated cases.
Sjögren's Syndrome: An autoimmune disorder that can cause joint pain and swelling, and while less commonly associated with anasarca, it can lead to systemic manifestations including fever.
Mixed Connective Tissue Disease (MCTD): This disease combines features of lupus, scleroderma, and rheumatoid arthritis, and can present with fever, polyarthralgia, and potentially anasarca due to its overlapping autoimmune features.

Septic Arthritis or Osteomyelitis: Infections within the joints or bones can cause fever, joint pain, and swelling. Anasarca could be a sign of severe systemic infection or sepsis, which is life-threatening and requires immediate intervention.
Lymphoma: Certain types of lymphoma can cause systemic symptoms like fever, joint pain, and swelling due to lymph node enlargement or tumor lysis syndrome, which could lead to anasarca.
Acute Rheumatic Fever: Following a streptococcal infection, this condition can cause fever, polyarthralgia, and potentially anasarca, especially if there's significant cardiac involvement leading to heart failure.

Multicentric Castleman's Disease: A rare disorder that involves an overgrowth of cells in the body's lymph nodes, which can cause fever, joint pain, and swelling, along with generalized edema.
Familial Mediterranean Fever: An inherited condition characterized by recurrent episodes of fever, often accompanied by pain in the abdomen, chest, or joints, and potentially generalized edema during severe attacks.
Eosinophilia-Myalgia Syndrome: A rare condition that can cause severe muscle pain, fever, and potentially edema, associated with elevated eosinophil counts, often linked to certain medications or toxins.