Histiocytosis X: an oral diagnostic problem.

A case of prepubertal periodontitis in a 6 1/2-year-old boy is described. Following failure to respond to conventional treatment including scaling, oral hygiene instruction and tetracycline therapy, a biopsy was performed and root planing carried out. The biopsy revealed histiocytic infiltration and a diagnosis of Histiocytosis X of the Hand-Schüller-Christian type was made. This case emphasises the role of biopsy in establishing a diagnosis in cases of prepubertal periodontitis that do not respond to conventional therapy.