T-cell-prolymphocytic leukemia (T-PLL) is a mature T-cell leukemia with aggressive behavior and predilection for blood, bone marrow, lymph nodes, liver, spleen, and skin involvement. T-PLL is a very rare leukemia, primarily affecting adults over the age of 30. It represents 2% of all small lymphocytic leukemias in adults. Other names include T-cell chronic lymphocytic leukemia, "knobby" type of T-cell leukemia, and T-prolymphocytic leukemia/T-cell lymphocytic leukemia.

Reference
Wiki: T-prolymphocytic leukemia