A 58-year-old man was seen with an 8-month history of an asymptomatic ulcerated lesion of the oral mucosa. Physical examination revealed a 4 × 6-mm necrotic ulceration on the lower left gingiva (Figure 1). A whitishindurated material was exposed through the mucosa, and it was easily removed with forceps (Figure 2). No other mucous or cutaneous lesions were observed. His medical history was remarkable for a prostate adenocarcinoma treated surgically in 2004 and multiple myeloma diagnosed in 2006 that had been treated with bortezomib, intravenous zoledronate, and syngenic hematopoietic stem cell transplantation. Two years later, the patient was free of disease, and his drug regimen was reduced to zoledronate only. He denied previous radiotherapy on the left jaw. Histologic examination of the exposed material was performed (Figure 3).