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LOCALIZED RELAPSE OF CHRONIC MYELOID LEUKAEMIA POST ALLOGENEIC BONE MARROW TRANSPLANTATION

Extramedullary relapse of chronic myeloid leukaemia (CML) is a well-recognized clinical entity and is usually associated with a poor prognosis and rapid evolution to blastic transformation in the bone marrow (Terjanian et al. 1986). We describe an unusual pattern of recurrent extramedullary relapse following allogeneic bone marrow transplantation (BMT) for megakaryoblastic transformation of CML. The extramedullary disease has been associated with long survival and apparent continuing bone marrow remission. A 19-year-old woman presented in 1984 and was diagnosed as having Philadelphia chromosome positive CML. She was commenced on busulphan and her sister was found to be HLA compatible. The patient, however, declined bone marrow transplantation. In December 1987 the WBC rose to 50 x 109/1 with 10 x 109/1 blasts. The bone marrow was markedly fibrotic, with atypical megakaryocytes and infiltration with a population of megakaryoblasts. Cytogenetics showed clonal evolution with two cell populations 46,XX.t(9;22)(q34;qll) and 48,XX, + 8, + 19,t(9;22) (q34:qll) present. A diagnosis of acute megakaryoblastic transformation of CML was made and the patient underwent allogeneic bone marrow transplantation using busulphan/ cyclophosphamide conditioning. Graft-versus-host disease (GVHD) prophylaxis was with cyclosporin A and methotrexate. By day 90 her bone marrow was morphologically and karyotypically normal. Chronic GVHD with involvement of skin, gut and liver developed at day 120. This eventually resolved with no permanent sequalae following treatment over an 18-month period with cyclosporin A, prednisolone and azathioprine. Two years post transplant the patient developed right hip pain and an osteolytic lesion was demonstrated in the right femoral neck. Biopsy showed a population of CD41 positive blast cells supporting a diagnosis of locally relapsed acute megakaryoblastic leukaemia. A bone marrow performed from the left iliac crest was normal both morphologically and cytogenetically. The area of relapse in the femoral neck was treated with local radiotherapy with complete resolution of the patient’s symptoms and signs. In January 1991 the patient complained of increasing abdominal pain and intermittent diarrhoea. A CT scan demonstrated para-aortic lymphadenopathy and thickening of a localized area of the small bowel. A laparotomy was performed and a pedunculated tumour obstructing the small bowel was resected. Histology of the small bowel tumour and associated lymph nodes demonstrated the presence of a CD41/CD61 positive cell population consistent with a further localized magakaryoblastic relapse. Cytogenetics of both the small bowel tumour and lymph nodes demonstrated the presence of a 47,XX, + 19,t(9;22)(q34;qll) cell population and Southern analysis showed a bcr-abl rearrangement to be present in both tissues (Fig 1). The bone marrow throughout this period remained morphologically normal with no demonstrable Philadelphia chromosome. In addition there was no evidence of bcr-abl rearrangement or transcript detectable by Southern blotting or PCR analysis respectively. The patient commenced cytarabine, etoposide and daunorubicin induction chemotherapy with resolution of her abdominal pain and lymphadenopathy. Two courses of consolidation chemotherapy were given and the patient remained in apparent remission for 6 months before experiencing a further local abdominal recurrence in paraortic lymph nodes. At the present time the patient has just undergone a course of palliative deep X-ray therapy to the abdomen. Her bone marrow remains normal by morphological, cytogenetic and molecular criteria (Fig 1). The pattern of extramedullary disease in this patient is unusual. Although bone and lymph node involvement is well recognized in chronic myeloid leukaemia, gastrointestinal tract involvement is rare (Jacknow et al, 1985: Terjanian et