KRAS Mutation in an Implant-associated Peripheral Giant Cell Granuloma of the Jaw: Implications of Genetic Analysis of the Lesion for Treatment Concept and Surveillance

Abstract

The aim of this case report was to detail diagnosis and therapy in a case of implant-associated peripheral giant cell granuloma (IA-PGCG) of the jaw. Case Report: The 41-year-old female attended the outpatient clinic for treatment of recurrent mandibular IA-PGCG. The lesion was excised and the defect was closed with a connective tissue graft of the palate. Healing of oral defects was uneventful, and no local recurrence has occurred during a follow-up of 7 months. Genetic examination of the lesion identified a somatic mutation in KRAS. Conclusion: The lesions are assessed as reactive-inflammatory changes in the mucous membrane of the oral cavity. The cause of the lesion is unknown. KRAS mutations are commonly found in various cancer tissues, but also in germline and mosaic RASopathies. Recently, KRAS mutations have been identified in several IA-PGCG. The clinical course of a frequently locally recurring lesion gives rise to the assumption that lesions of this type show characteristics known in benign neoplasms.

Keywords: Giant cell granuloma; KRAS mutation; dental implant; epulis gigantocellularis.

Figure 1. Excision and covering of the mucogingival defect with connective tissue flaps. (A) Vestibular view of the peri-implant lesion on the right side of the lower jaw. (B) Circular excision of the soft tissue around the lesion (with safety margin of apparently normal mucosa). (C) Peri-implant soft tissue defect. (D) Palatal connective tissue transplant situated on the vestibular defect side. (E) Epithelial coverage of the graft by mobilized marginal mucosa. (F) Excised specimen in toto and (G) after cutting the lesion in two halves exposing the erythematous lesion.

Figure 2. (A) Histology revealed a nodular lesion located beneath the squamous epithelium, limited to the gingiva. (B) This nodule had no capsule but was relatively well-circumscribed. (C) The lesion consisted of mononuclear spindle-shaped and polygonal cells, as well as prominent multinucleated giant cells. The background was well vascularized with fresh hemorrhage and hemosiderin pigment. (D) The nuclei of the mononuclear component and the giant cells were identical. Cellular atypia was not detectable. In summary, the lesion was classified as a characteristic example of peripheral giant cell granuloma.