下肢に多発結節を呈したTリンパ芽球性リンパ腫

・下肢に多発結節を呈したTリンパ芽球性リンパ腫（T-cell lymphoblastic lymphoma：T-LBL）の1例を経験した． ・一般にT-LBLは高悪性度のリンパ腫で，中枢神経浸潤や白血化が早期に生じるため，迅速な診断確定が必須である． ・自験例は皮膚病変を契機に診断に至った.病変は皮膚と骨に限局し，T-LBLとしては進行が緩徐な症例であった． ・T-LBLはterminal deoxynucleotidyl transferase（TdT）やc-kitなどの前駆リンパ球マーカーの免疫組織化学染色により，他のリンパ腫と鑑別が可能である．悪性リンパ腫の皮膚浸潤が疑われる症例では，本症を念頭に置いた詳細な免疫組織化学染色が必要である． （「症例のポイント」より）

T lymphoblastic lymphoma with multiple nodules on the lower extremity Tsunoda, Kanako1）Takahashi, Norioko2）Takahashi, Kazuhiro2）Amano, Hiroo1） 1）Department of Dermatology, Iwate Medical University 2）Kamikumimachi Hohoemi Skin Clinic Abstract A 42-year-old male presented with a one-year history of multiple nodules on the lower extremity. Physical examination revealed a red-brownish hard mass with erosion. Histopathological examination demonstrated diffuse infiltration of small- to medium-sized heterozygous lymphocytes with a high N/C ratio extending from the upper dermis to the subcutaneous tissue. Immunohistochemical staining revealed positive immunoreactivity for TdT, c-kit, CD3 and CD7 and negativity for CD20, CD79a, CD34, CD56, MPO, granzyme B and EBER. On the basis of these findings, a diagnosis of T lymphoblastic lymphoma was made. Four courses of chemotherapy were carried out, and the nodule disappeared. Thereafter, the patient underwent bone marrow transplantation, and remained in remission without recurrence. Although T lymphoblastic lymphoma is highly malignant, the present case was manifested only as skin lesions and showed an indolent course.