[A case of dysthymic pathology in a 16-year-old adolescent].

Dysthymia in children and adolescents, illustrated by a sixteen-year-old-girl's clinical history, raises different diagnostic, therapeutic and prognostic problems. Diagnostic, since dysthymia in children and adolescents has specific peculiarities (often mixed manic episodes, variable expression of depressive affect according to age, problem of the meaning of "masked depression"; Diagnostic again, since it is difficult to collect clearcut evidence ascertaining the diagnosis of manic-depressive syndrome in children: genuine periodicity in the occurrence of dysthymic episodes, family history of psychoses (manic-depressive syndrome, periodic psychosis, or other types of psychosis) and effectiveness of lithium are reliable criteria; Finally, differential diagnosis with the two other types of childhood psychosis: affective psychoses and severe dysthymic disorders; Therapeutic: the problem is to know when and on what evidence treatment with lithium can be started and, if called for, discontinued.