RESUMO
A 44-year-old male was diagnosed with acute myeloid leukemia with a complex karyotype. He underwent bone marrow transplantation using an HLA 6/6 antigen-matched sibling donor, but developed chronic graft-versus-host disease (cGVHD) with skin erythema and oral and esophageal lichen planus changes. Treatment with a combination of prednisolone and cyclosporine was initiated on day 646 after transplantation, but oral symptoms persisted. The patient developed bilateral osteonecrosis of the lower jaw after extraction of the lower left and right molars on days 2,861 and 3,339, respectively. As the disease gradually progressed, segmental mandibular osteotomy was performed. Biopsy specimens demonstrated proliferation of squamous epithelial carcinoma cells in the bilateral gingiva and lower jaw bone, which confirmed the diagnosis of bilateral gingival squamous cell carcinoma. Thus, gingival squamous cell carcinoma should be considered as a differential diagnosis in post-transplant patients with refractory osteonecrosis of the jaw during the course of cGVHD.