Clinical signs and symptoms at diagnosis and its differential diagnosis.

Anorexia, or loss of appetite, during the course of hematological malignancies can be due to gastrointestinal (GI) factors, treatment, neurological damage, psychiatric conditions, uncontrolled pain or cachexia. Cachexia is caused by cytokines produced by the tumor cells or the tumor microenvironment acting directly on the brain to cause a centrally induced anorexia or the cytokines can interfere with metabolic pathways. Different metabolic changes accompany increase in basal body expenditure, such as increased gluconeogenesis, increased consumption and decreased synthesis as well as increased catabolism of fats and proteins. Tumor necrosis factor, one of the main cytokines involved in cachexia, suppresses the function of lipoprotein lipase which is necessary for the storage of fat in tissues. Interleukin-1 (IL-1) may influence cachexia by increasing the levels of tryptophan, a precursor to serotonin in the brain. Serotonin and IL-1 have anorectic effects on the hypothalamus. The proinflammatory cytokine IL-6 is also involved in cachexia. A number of circumstances other than the hematologic malignancy may cause weight loss: chemotherapeutic agents and oral antibiotics, neurological impairment of swallowing or chewing, psychiatric disorders, oral abnormalities, hyperthyroidism, other severe chronic diseases, etc.