nodosa

Nodosa is a Latin-derived adjective meaning "knobby" or "node-bearing" and is used in medical terminology to describe conditions characterized by nodular changes or involvement of nodes. The best-known use is polyarteritis nodosa (PAN), a systemic vasculitis that affects medium-sized arteries.

Polyarteritis nodosa is an inflammatory disease that causes transmural necrotizing inflammation of medium-sized arterial walls and can involve the skin, kidneys, gastrointestinal tract, peripheral nerves, and other organs. It classically affects medium-sized arteries and often spares the small vessels of the glomeruli and lungs; however, organ involvement is variable.

Clinical features include fever, weight loss, myalgias, abdominal pain, hypertension, neuropathic pain or weakness, and various skin manifestations such as livedo reticularis or nodules. GI ischemia, mesenteric infarcts, and renal ischemia may occur.

Diagnosis relies on a combination of clinical presentation, imaging studies (angiography showing aneurysms and stenoses of medium-sized arteries), and tissue biopsy demonstrating necrotizing vasculitis. Laboratory testing may show elevated inflammatory markers, with hepatitis B surface antigen positivity in some historic cases; anti-neutrophil cytoplasmic antibodies are typically negative.

Treatment involves immunosuppression, most commonly corticosteroids; more severe or organ-threatening disease may require cytotoxic agents such as cyclophosphamide or newer biologics. When PAN is associated with hepatitis B infection, antiviral therapy and sometimes plasmapheresis are used in addition to immunosuppression. With modern therapy, prognosis has improved, though relapse can occur and untreated PAN may lead to organ failure.

Beyond polyarteritis nodosa, the term nodosa as a descriptor appears in other medical contexts to indicate nodular changes, but polyarteritis nodosa remains the primary example in contemporary usage.