Precursor T-acute lymphoblastic leukemia/lymphoma (ALL) comprises approximately 20–25% of adult cases of ALL. Precursor T-ALL tends to present in adolescent males as lymphomas and is characteristically presented with a high leukocyte count or large mediastinal mass at initial presentation. We report here a rare manifestation of precursor T-ALL presenting with clinically significant involvement of ovary and spine at initial presentation. A 33-year-old woman presented with low abdominal pain and lumbago for 1 day in July 2004. Physical examination revealed tenderness in the right lower abdominal region. No enlarged spleen, liver or lymph nodes was palpable. Hematologic data showed Hb level of 8.3 g/dl, 8.91×10/l of WBC with 87% of segmented neutrophils, 10% of lymphocytes, 3% of monocytes, and 328×10/l of platelets. An ultrasound examination of the pelvis revealed a cystic mass with a dimension of 6.5×4.5 cm in the right ovary. An emergent operation was performed for presumed symptomatic ovarian cyst. Ovarian masses were solid masses rather than cystic masses under the laparotomy, and right salpingooophorectomy with left ovary wedge resection was done. Histologic examination of the ovarian masses revealed lymphoblastic infiltration (Fig. 1a). They showed positive immunoreactivity for CD3 (cytoplasmic pattern), CD10 and CD45 (leukocyte common antigen) and negative immunoreactivity for CD20, CD30, CD117 and CD68. On the fourth postoperative day the patient developed abrupt-onset paraplegia and sensory loss of both lower extremities. Magnetic resonance imaging of the spine showed a dorsal epidural mass destroying from T9 to T12, and multiple enhancing lesions in L3, L4, S1 vertebral body were revealed (Fig. 1b). Emergency operative decompression of the spinal cord was done to relieve the lower extremity paraplegia. Autogenous iliac bone graft and from T7 to T12 posterolateral fusion following T9, 10, 11 total and T8 partial decompressive laminectomy was done after the removal of epidural mass. Histologic examination of the spinal mass revealed lymphoblastic and eosinophilic infiltration (Fig. 1c). The lymphoblasts were characterized by positive immunoreactivity for CD3 (cytoplasmic pattern), CD10 and CD45 (leukocyte common antigen) and negative immunoreactivity for CD20, CD30, CD117 and CD68. Under the impression of T lymphoblastic lymphoma, bone marrow examination was done. The bone marrow touch imprint preparation showed that 92% of marrow cells were lymphoblasts. They were variable in size and characterized by high nuclear–cytoplasmic ratio (Fig. 1d). Trephine biopsy showed diffuse infiltration of marrow by lymphoblasts, which revealed numerous mitotic figures (Fig. 1e). Immunohistochemical stain showed positive reactivity for CD3 (cytoplasmic pattern) and negative for CD20 (Fig. 1f). Chromosomal analysis of bone marrow demonstrated a 46XX karyotype in 100% (20/20) of the cells. A CT scan of the chest demonstrated an anterior mediastinal mass approximately 12×8 cm. A diagnosis of precursor T-ALL was made. The patient was started on induction chemotherapy with vincristine, prednisone, daunorubicin and L-asparaginase (VPDL). The anterior mediastinal mass regressed substantially and revealed a focal streaky density on followup chest CT checked on 28 June 2004. In August 2004, remission was successfully achieved as shown by follow-up bone marrow examination. The patient subsequently received further consolidation VPDL therapy and currently remains in good health. Precursor T-ALL is associated with numerous unfavorable presenting features; thus, patients have a worse prognosis than patients with precursor B-ALL. In adults, higher white blood cell counts (>30,000/μl) and older age (>60 years) shorten durations of remissions and overall survival M.-A. Kim (*) . K.-Y. Maeng Department of Laboratory Medicine, Gyeongsang National University Hospital, 90 Chilam-Dong, Jinju, 660-702, South Korea e-mail: givmea2004@yahoo.co.kr Tel.: +82-55-7508639 Fax: +82-55-7622696