T-small cell disorders.
A minority (less than 2%) of all lymphoproliferative disorders are derived from small T cells. These include T-cell prolymphocytic leukemia, T-cell granular lymphocytic leukemia, and mycosis fungoides/Sézary syndrome. With the possible exception of early-stage, skin-localized mycosis fungoides, all are considered incurable, although palliation can be achieved with radiation therapy, chemotherapy, biologic therapy, and combinations of these modalities. Of these disorders, mycosis fungoides is the most common; it follows an indolent, though gradually progressive, course that spans years. The T-cell prolymphocytic leukemias, in contrast, are generally refractory to treatment, with a median survival of typically less than 1 year. Although effective therapy remains elusive in most cases, the development of nucleosides as a class of chemotherapeutic agents and biologics, including interferon, monoclonal antibodies, and vitamin A derivatives, offers new hope for at least more effective palliation of these progressive lymphoproliferative disorders. However, rapid improvement in the treatment of these disorders remains hampered by the rarity of these individual entities. More rapid progress in treatment depends on national and international cooperation to accrue patients for definitive trials of sufficient size to evaluate new treatment options quickly.