Acute lymphoblastic leukemia and non-Hodgkin's lymphoma with mediastinal mass--a study of 23 children; different disorders or different stages?

Phenotype and TCR-gamma gene rearrangements in a Malaysian cohort of T-cell leukaemia/lymphoma cases

T cells undergo a series of complex phenotypic changes before achieving maturation. Discrete stages of T-cell differentiation are simplified to four stages (pro-, pre-, cortical and mature-T cell) and used in the classification of T-cell leukaemia. HLA-DR has been reported to be expressed in immature T-cell acute lymphoblastic leukemia (ALL) and also confer a poorer treatment outcome. Simultaneously, the genotype goes through distinct pattern changes due to rearrangement of T-cell receptor (TCR) genes. TCR gene rearrangement is important in the diagnosis of clonality and used as markers to detect minimal residual disease in lymphoproliferative disorders. We identified a subset within Pro-T and Pre-T cell cases distinguished by the expression of HLA-DR. These subgroups appeared to be more immature as rearrangement of the TCR-gamma gene was either at germline or involved only the first constant region (C1) unlike a more rearranged pattern in the HLA-DR-subgroups. We also observed a higher incidence of mediastinal mass (67%) in the HLA-DR-subgroup in the Pre-T stage. These characteristics may be useful as markers to further refine staging of T-cell ALL and determine prognosis.

Cytogenetic findings in pediatric T-lymphoblastic lymphomas: one institution's experience and a review of the literature

Cytogenetic analyses of lymphomas commonly reveal nonrandom chromosomal abnormalities, but there are relatively few reports in childhood lymphoblastic lymphoma (LL). We retrospectively reviewed G-banded karyotypic analyses performed at Arkansas Children's Hospital between 1990 and 2004. Six children (2 to 20 years old) had LL that presented as mediastinal or cervical masses and had a T-cell immunophenotype and clonal abnormalities. The cytogenetic findings in these 6 patients were as follows: 46,XX,-7,inv(9)(p11q12),der (12)t(7;12)(q11.2;p13),t(16;18)(p13.1;q21),+22 in patient 1; 47,XX,+9,del(9)(q11q22)x2 in patient 2; 72-119, XY,+X,+1,+1, inv(2) (p11q13),-3,+5,+6,+7,+10,-12,-16, -21,-21,-22,+mar in patient 3; 48,XY,+5,+20,t(7;9) (q32;q34) in patient 4; 47 approximately 48,XX,der(10)t(10;14)(q23; q11.2),+12, del(12)(p12)x2, -14,del(16)(q22q22),+?add (19)(p13.3) in patient 5; and 48 approximately 49,XY,+7,+8,t(11;19) (q23;p?13.3),+der(19)t(11;19)[cp20] in patient 6. Eleven chromosome breakpoints in 6 of our patients (7q11, 12p13, 16p13, 18q21, 9q11, 2p11, 2q13, 7q32, and 7q23) have been reported in other patients with acute lymphoblastic leukemia or LL and involved regions containing TEL, ABL, E2A, MLL, and T-cell receptor-alpha genes. A review of the cytogenetic findings of these and other cases of LL reveals that clonal aberrations are common and most frequently involve T-cell receptor gene regions. The aberrations show some features similar to those of acute lymphoblastic leukemia and are not unique to LL, thus furnishing additional evidence of the equivalence of these two diseases. The cytogenetic features of LL may be helpful in the diagnosis of pediatric lymphomas and undifferentiated neoplasms.

Mediastinal mass in childhood T-cell acute lymphoblastic leukemia: significance and therapy response

BACKGROUND

T-cell acute lymphoblastic leukemia (T-ALL) accounts for approximately 10-13% of childhood ALL cases. Patients with T-ALL frequently present with unfavorable features at diagnosis and thus are considered to have a higher risk to relapse. Within the last 10 years, the previously dismal prognosis of this ALL subtype has been improved by intensified chemotherapy. However, 30-40% of patients still relapse, so that additional prognostic factors such as the local response of the mediastinal mass to therapy might allow defining the patients at risk in a better manner.

PROCEDURE

A retrospective analysis of 116 Austrian patients with T-ALL was performed to assess whether an initial mediastinal mass (70/116) and its response to chemotherapy as measured by thoracic X-rays (32/70) might predict outcome.

RESULTS

Neither patients with a mediastinal tumor at the time of diagnosis nor patients with an incomplete response on day 35 or 70 of therapy had a worse prognosis, as compared with the group of patients with no initial tumor and complete regression on day 35 and 70.

CONCLUSIONS

We failed to show that in children with T-ALL residual mediastinal tumors are of prognostic relevance. This might suggest that incomplete local response is not necessarily an indication for treatment intensification such as local irradiation, second-look operation, or high-dose chemotherapy with bone marrow rescue. However, due to the relatively small number of patients analyzed, our results have to be validated prospectively on a larger cohort of patients in future clinical trials.

Primary mediastinal tumors: part II. Tumors of the middle and posterior mediastinum

Lymphoma, mediastinal cysts, and neurogenic neoplasms are the most common primary middle and posterior mediastinal tumors. Lymphoma may involve the anterior, middle and/or posterior mediastinum, frequently as lymphadenopathy or as a discrete mass. Foregut cysts are common congenital mediastinal cysts and frequently arise in the middle mediastinum. Pericardial cysts are rare. Schwannoma and neurofibroma are benign peripheral nerve neoplasms, represent the most common mediastinal neurogenic tumors, and rarely degenerate into malignant tumors of nerve sheath origin. Sympathetic ganglia tumors include benign ganglioneuroma and malignant ganglioneuroblastoma and neuroblastoma. Lateral thoracic meningocele is a rare cause of a posterior mediastinal mass.