Potential role of hematopoietic stem cell transplantation in children with secondary acute lymphocytic leukemia

Secondary acute lymphocytic leukemias (ALL) are uncommon events in the pediatric patient population. There are few detailed reports on the laboratory characteristics and clinical course of patients with secondary lymphocytic leukemia. Historically, these patients have had a poor outcome. We report two patients treated at one institution who developed treatment-related secondary ALL. Both patients underwent hematopoietic stem cell transplantation, one with a compatible unrelated donor cord blood unit and one with an HLA-matched sibling donor bone marrow. One of the two patients survives disease-free 3 years after transplantation.

Activation of the mitogen-activated protein kinase pathway is involved in and sufficient for megakaryocytic differentiation of CMK cells

Activation of the mitogen-activated protein (MAP) kinase pathway has been associated with both cell proliferation and differentiation. Constitutively activated forms of Mek (MAP kinase/Erk kinase) and Erk (MAP kinase) have been previously shown capable of inducing differentiation or proliferation in nonhematopoietic cells. To specifically examine the role of Erk activation in megakaryocytic growth and development, we activated the MAP kinase pathway by the transfection of constitutively activated Mek or Erk cDNA into a human megakaryoblastic cell line, CMK, by electroporation. The CMK transfectant clones that expressed constitutively activated Mek or Erk showed morphologic changes of differentiation. Transfected cells also showed expression of mature megakaryocytic cell surface markers. The MAP kinase pathway was also activated by treatment of the hematopoietic cells with a cytokine that activates Erk. The treatment of CMK cells with stem cell factor (SCF ) caused MAP kinase activation and induced differentiation by the expression of mature megakaryocytic cell surface markers. The effects of the SCF treatment were inhibited by pretreatment with a specific inhibitor of the MAP kinase pathway, PD98059. In this report, we conclude that activation of the MAP kinase pathway was both necessary and sufficient to induce differentiation in this megakaryoblastic cell line.

Extranodal spread of anaplastic large cell (CD30+) lymphoma presenting as a cutaneous perivascular infiltrate

Cutaneous lesions of anaplastic large cell (CD30+) lymphoma (ALCL) typically present as solitary or multiple ulcerated nodules. This tumor is histologically characterized by a diffuse dermal and sometimes subcutaneous infiltrate composed of bizarre, pleomorphic, neoplastic cells that may be occasionally multinucleated. We report a case of extranodal spread of ALCL to the skin in a 2 1/2-year-old boy presenting as a widespread papular eruption that on biopsy showed lymphoma restricted to the perivascular and periadnexal dermis.