A 58-year-old man named J.S. was diagnosed with non-Hodgkin lymphoma and underwent treatment with standard rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemotherapy. He presented to his local outpatient clinic for evaluation and laboratory tests on day 10 after cycle 3. During this visit, J.S. reported great difficulty opening his mouth with significant gingival and lingual pain when eating and drinking in spite of prophylactic oral care. Laboratory test results revealed a white blood cell count of 0.9 k/ul, hemoglobin level of 8.9 g/dl, platelets of 100 k/ul, serum creatinine level of 1 mg/dl, and blood urea nitrogen level of 29 mg/dl.