[Diffuse gingival plasmocytoma: a rare location of extra-osseous solitary plasmocytomas (author's transl)].

A 51-year-old man presented with isolated diffuse gingival hypertrophy, the diagnosis of a plasmocytoma being suspected after pathological and immunohistological examinations of a gingival biopsy (light chain lambda plasmocytes). The isolated nature of this diffuse gingival plasmocytoma was confirmed by biological tests and radiological investigations. The evolution of solitary plasmocytomas is variable, and while certain of these lesions remain isolated even after many years, other plasmocytomas, apparently local, are associated with myelomas which either become evident or may sometimes develop. The extremely rare nature of diffuse gingival locations of extra-osseous solitary plasmocytomas is confirmed by a review of the published literature. Studying histological sections by immunofluorescence enables the polyclonal or monoclonal nature of the plasmocytes to be established, this distinction being an important element in the prognosis.