Diffuse large B-cell lymphoma arising in a patient with neurofibromatosis type I and in a patient with neurofibromatosis type II.

We experienced two unusual cases of diffuse large B-cell lymphoma (DLBCL), which occurred in a patient with neurofibromatosis type I and a patient with neurofibromatosis type II. B-cell lymphoma is one of the most common phenotypic subgroups of malignant lymphoma. Neurofibromatosis I is characterized by café-au-lait spots and neurofibromas. Neurofibromatosis II typically consists of bilateral schwannomas of the acoustic nerve. Malignant lymphomas rarely coexist with neurofibromatosis I, and no coexistence with neurofibromatosis II has been reported. The patient with neurofibromatosis I was a 50-year-old Japanese woman, clinically manifesting von Recklinghausen's disease since infancy, who noticed an egg-sized tumor in her shoulder. The patient with neurofibromatosis II was a 39-year-old Japanese man who noticed multiple soft tissue tumors in his neck, buttock, and elbow. Biopsied materials from both cases were examined by multiparameter methods, including flow cytometry. Flow cytometry revealed large-scale cells to be tumor cells, and they were positive for CD19, CD20, and CD22. Both patients received chemotherapy, and the tumors disappeared. The patient with neurofibromatosis I was alive without recurrence at 4 years after treatment, while the patient with neurofibromatosis II died of recurrence. To the best of our knowledge, this is the first case of malignant lymphoma arising in a neurofibromatosis II patient. As for neurofibromatosis I, there were some reports about occurrence of malignant lymphoma. It is important to be aware of possibility of association of malignant tumors not only of the nervous system but also of unrelated to the nervous system when tumors appear in neurofibromatosis patients.