A rare case of osteonecrosis of the jaw related to imatinib.

Osteonecrosis of the jaw (ONJ) is commonly described as an adverse effect of the use of bisphosphonates. A few cases of ONJ associated with tyrosine kinase inhibitors (sunitinib, imatinib) have been reported in the literature and usually they occurred in patients simultaneously treated with bisphosphonates. We report an atypical case of ONJ related only to imatinib. A 72-year-old male patient was treated with imatinib for metastases from gastrointestinal stromal tumors (GISTs). The patient developed ONJ after 22 months of imatinib only therapy. During his whole life, the patient had never been treated with bisphosphonates or radiotherapy. Microscope examination of the tissues confirmed the clinical diagnosis of diffuse osteonecrosis and showed absence of neoplastic cells. Thus, secondary localisations from GISTs were ruled out. Osteonecrosis of the lower jaw appeared 22 months after initial and exclusive therapy with imatinib. Therefore, imatinib monotherapy can induce ONJ in patients that have never been treated with bisphosphonates or radiotherapy.