Tangier disease (TD) is a rare lipoprotein metabolism disorder characterized biochemically by an almost complete absence of plasma high-density lipoproteins (HDL), and clinically by liver, spleen, lymph node and tonsil enlargement along with peripheral neuropathy in children and adolescents, and, occasionally, cardiovascular disease in adults.

An organ or organ-system abnormality that consists of uncontrolled autonomous cell-proliferation which can occur in any part of the body as a benign or malignant neoplasm (tumour).