Large cell anaplastic lymphoma (Ki-1 lymphoma).

The "large cell anaplastic lymphoma, Ki-1 positive" is a recently described lymphoma subtype (about 1-8% of all NHL). Distinction from Hodgkin's disease and true histiocytic lymphoma/malignant histiocytosis is not always possible, even by experienced pathologists. It was recently incorporated in the updated Kiel Classification of lymphomas. Classical histologic appearance is a sinusoidal growth pattern in lymph nodes and presence of large bizarre anaplastic cells. Use of cell markers LCA, EMA and Ki-1 or Ber-H2 is essential for diagnosis. The mean age of patients is 50 years. Approximately 50% of patients have an advanced stage (III-IV). Prognosis depends on age and tumor localisations. Cutaneous involvement only is usually associated with a good prognosis. Median survival for patients with extra-cutaneous disease is 13 months. Treatment with intensive chemotherapy is usually needed. Long term remissions are more frequently seen in children and adolescents.