Anaplastic large cell lymphoma-propagating cells are detectable by side population analysis and possess an expression profile reflective of a primitive origin.

Cancer stem cells or tumour-propagating cells (TPCs) have been identified for a number of cancers, but data pertaining to their existence in lymphoma so far remain elusive. We show for the first time that a small subset of cells purified from human anaplastic lymphoma kinase (ALK)-positive and -negative, anaplastic large cell lymphoma cell lines and primary patient tumours using the side population (SP) technique have serial tumour-propagating capacity both in vitro and in vivo; they give rise to both themselves and the bulk tumour population as well as supporting growth of the latter through the production of soluble factors. In vivo serial dilution assays utilising a variety of model systems inclusive of human cell lines, primary human tumours and nucleophosmin (NPM)-ALK-induced murine tumours demonstrate the TPC frequency to vary from as many as 1/54 to 1/1336 tumour cells. In addition, the SP cells express higher levels of pluripotency-associated transcription factors and are enriched for a gene expression profile consistent with early thymic progenitors. Finally, our data show that the SP cells express higher levels of the NPM-ALK oncogene and are sensitive to an ALK inhibitor.

Serum levels of mature microRNAs in DICER1-mutated pleuropulmonary blastoma.

DICER1 is a critical gene in the biogenesis of mature microRNAs, short non-coding RNAs that derive from either -3p or -5p precursor microRNA strands. Germline mutations of DICER1 are associated with a range of human malignancies, including pleuropulmonary blastoma (PPB). Additional somatic 'hotspot' mutations in the microRNA processing ribonuclease IIIb (RNase IIIb) domain of DICER1 are reported in cancer, and which affect microRNA biogenesis, resulting in a -3p mature microRNA strand bias. Here, in a germline (exon11 c.1806_1810insATTGA) DICER1-mutated PPB, we first confirmed the presence of an additional somatic RNase IIIb hotspot mutation (exon25 c.5425G>A [p.G1809R]) by conventional sequencing. Second, we investigated serum levels of mature microRNAs at the time of PPB diagnosis, and compared the findings with serum results from a comprehensive range of pediatric cancer patients and controls (n=52). We identified a panel of 45 microRNAs that were present at elevated levels in the serum at the time of PPB diagnosis, with a significant majority noted be derived from the -3p strand (P=0.013). In addition, we identified a subset of 10 serum microRNAs (namely miR-125a-3p, miR-125b-2-3p, miR-380-5p, miR-125b-1-3p, let-7f-2-3p, let-7a-3p, let-7b-3p, miR-708-3p, miR-138-1-3p and miR-532-3p) that were most abundant in the PPB case. Serum levels of two representative microRNAs, miR-125a-3p and miR-125b-2-3p, were not elevated in DICER1 germline-mutated relatives. In the PPB case, serum levels of miR-125a-3p and miR-125b-2-3p increased before chemotherapy, and then showed an early reduction following treatment. These microRNAs may offer future utility as serum biomarkers for screening patients with known germline DICER1 mutations for early detection of PPB, and for potential disease-monitoring in cases with confirmed PPB.

Mediastinal masses masquerading as common respiratory conditions of childhood: a case series.

INTRODUCTION: Leukaemia and lymphoma may present with symptoms and signs mimicking common respiratory conditions of childhood such as asthma or croup. The UK National Institute for Clinical Excellence guidelines for referral for suspected cancer state that "the primary healthcare professional should be ready to review the initial diagnosis in patients in whom common symptoms do not resolve as expected" and "must be alert to the possibility of cancer when confronted by unusual symptom patterns" (National Institute for Health and Clinical Excellence, 2005). RESULTS AND DISCUSSION: A child with an undiagnosed mediastinal mass presenting with signs and symptoms suggestive of asthma or croup may be given oral systemic steroids. We report four such illustrative cases presenting to a single institution within the last 3 years. CONCLUSION: We highlight key points from the history and examination findings which should lead to review of the original diagnosis, the benefit of early chest X-ray in such cases and the dangers of steroid pretreatment.

The clinical relevance of detection of minimal residual disease in childhood acute lymphoblastic leukaemia.

Risk directed treatment forms a central component of modern protocols for childhood acute lymphoblastic leukaemia (ALL). A review of recent studies of minimal residual disease (MRD) analysis shows that it is a powerful prognostic factor in both first line and relapse treatment. However, the value of MRD analysis is both time point and protocol specific, and the threshold for MRD detection of the technique used impacts upon the results obtained. MRD analysis does have a useful role to play in the risk directed treatment of childhood ALL, and this is currently being investigated in large prospective studies.