The natural history of adult T-cell leukemia varies between the different subtypes of the disease. Common complications of adult T-cell leukemia include cardiac arrhythmias, opportunistic infections , and bone fractures. The prognosis varies between the subtypes of adult T-cell leukemia; acute and lymphomatous subtypes have a poor prognosis, where as chronic and smouldering subtypes have a good prognosis.

• The natural history of adult T-cell leukemia varies between the different subtypes of the disease.^[1]
• Usually patients with acute adult T-cell leukemia have an aggressive clinical course with a median survival period of less than 12 months. If left untreated, most of the patients with acute adult T-cell leukemia will develop constitutional symptoms, lymphadenopathy, and organomegaly within a few weeks of diagnosis.
• Usually patients with chronic adult T-cell leukemia will have an stable clinical course. If left untreated, most of the patients with chronic adult T-cell leukemia will develop lymphocytosis for months, or even years, before presenting with the typical cutaneous manifestations.
• Most patients with smoldering adult T cell leukemia are initially asymptomatic. If left untreated, most of the patients with smoldering adult T cell leukemia will develop steroid-responsive skin rash and multiple lung infiltrates.

• Common complications of adult T-cell leukemia include:^[1][2]

• Cardiac arrhythmias (due to hypercalcaemia)
• Opportunistic infections (Strongyloides stercoralis infection is a frequent cause of death among adult T-cell leukemia patients)
• Bone fractures (due to lytic bone lesions)
• Anemia
• Recurrent bleeding

• The prognosis varies between the subtypes of adult T-cell leukemia; acute and lymphomatous subtypes have a poor prognosis, where as chronic and smoldering subtypes have a good prognosis.^[3]

• The 4-year overall survival rate of patients with acute adult T-cell leukemia is approximately 11%.
• The 4-year overall survival rate of patients with adult T-cell lumphoma is approximately 16%.
• The 4-year overall survival rate of patients with chronic adult T-cell leukemia is approximately 36%.
• The 4-year overall survival rate of patients with smouldering adult T-cell leukemia is approximately 52%.

• The table below lists prognostic factors for adult T-cell leukemia patients:^{[1][3][4] [5]}