T-cell ProLymphocytic Leukemia (T-PLL)

An elevated white blood count (>100 x 109/L) is common, often combined with hepatosplenomegaly (75 percent) and generalized lymphadenopathy (50 percent).
Morphologically three different types can be distinguished:
* Medium-sized cells with round to oval nucleus, moderately condensed chromatin and a visible nucleolus, moderately abundant faintly basophilic cytoplasm with cytoplasmatic blebs.
* Small cells with condensed chromatin and no visible nucleolus.
* Cerebriform (Sézary cell-like) variant: the cells have a very irregular nuclear outline resembling the cerebriform nucleus of Sézary cells.

By flowcytometry the cells typically show strong expression of CD2 and CD7, co-expression of CD4 and CD8 is seen in 25% (unique to T-PLL in mature T-cell proliferations), CD4+/CD8- is seen in 60% and 15% is CD4-/CD8+.