Every B-lymphocyte carries a unique sequence of the immunoglobulin heavy chain (IgH) gene, which serves as a marker for tumor cells derived from clonal B-lymphocyte expansion. Southern blot analysis for IgH gene rearrangement is not suitable for small biopsies and formalin-fixed, paraffin-embedded tissues. We aimed to assess the application of PCR techniques to demonstrate clonal IgH gene rearrangement in B-cell non-Hodgkin's lymphoma (B-NHL). A series including 119 B-NHL, 10 T-cell NHL, 6 reactive lymphoid hyperplasia, and 15 non-lymphoid malignancies were examined. DNA was extracted from paraffin-embedded tissues by proteinase K digestion. A semi-nested PCR amplification targeting two framework regions (Fr2A and Fr3A) and the joining region (JH) of the variable gene segment of the IgH gene was performed. Clonal IgH gene rearrangement was detected in 30% and 63% of B-NHL with Fr2A and Fr3A assays, respectively, and 74.8% when both assays were combined. Clonal IgH gene rearrangement was not demonstrated in any of the reactive lymphoid hyperplasia and non-lymphoid malignancies. However, 20.0% of the T-NHL showed clonal IgH gene rearrangement. Differences were noted among different subtypes of B-NHL. Clonal IgH gene rearrangement was detected in all of the low-grade B-NHL, except follicular lymphoma. High-grade B-NHL generated heterogeneous results.
A variant of Epstein-Barr virus (EBV) with a 30-base pair (bp) deletion in the latent membrane protein-1 (LMP-1) gene has been reported in many EBV-associated malignancies at different frequencies in different geographical locations. This study aims to determine the frequency of this variant in Asian EBV-associated lymphomas. We analyzed a total of 81 cases of known EBV-associated lymphomas [20 classical Hodgkin's, 19 Burkitt's, 33 T-and natural killer (NK)/T-cell, and 9 diffuse large B-cell lymphomas (DLBCL)] and 19 reactive lymphoid tissues from the archives. The presence of the 30-bp deletion at the 3' end of the LMP-1 gene was demonstrated by hybridization of polymerase chain reaction (PCR) products after amplification with a pair of primers flanking the deletion region. The DNA from 96.3% (78/81) of the lymphomas and 78.9% (15/19) of the reactive lymphoid tissues were amplified by PCR. The lymphomas showed infection by the deleted variant in 91.0% (71/78) of the cases, including 33.3% (26/78) cases with dual variant infection. The deleted variant was observed in 100% (19/19) of the Burkitt's lymphoma, 89.5% (17/19) of the classical Hodgkin's lymphomas, 90.6% (29/32) of the T-and NK/T-cell lymphomas and 75.0% (6/8) of DLBCL, whereas it was detected in 60.0% (9/15) of the reactive lymphoid tissues. The difference in the frequency of deleted LMP-1 variants observed between the lymphomas and the reactive lymphoid tissues was statistically significant (p=0.006). A significant difference was also observed between childhood and male lymphoma patients and reactive lymphoid controls of comparable age or gender group (p<0.001 and p=0.012 respectively). In conclusion, a high frequency of the 30-bp deletion in the LMP-1 gene was observed in the Malaysian population. The significantly higher percentage of deleted variant observed in EBV-associated lymphomas suggests the possibility of a selection mechanism during malignant transformation.
Intracellular signaling via the B-cell antigen receptor (BCR) regulates cellular dynamics in B cells, in a similar way to signaling via the T-cell receptor (TCR) in T lymphocytes. Cross-linking of BCR increases Ca2+ influx as a first event, which then activates Ca2+-dependent signaling molecules. Calcineurin and nuclear factor of activated T cell (NFAT) are Ca2+-mobilizing elements that are considered to be important in regulating proliferation of T cells. However, little is known about their expression in B cells, especially in the germinal center, where apoptosis and proliferation of B cells actively take place for clonal selection. We investigated the expression and the localization of Ca2+-mobilizing molecules, including calcineurin and NFAT, in germinal center B cells by immunofluorescence. The results revealed a dramatic increase of intracellular Ca2+, a constitutive expression of calcineurin, and a unique localization of NFATc2. Interestingly, several germinal center B cells expressed nuclear-imported NFATc2, which suggests the activation of NFATc2 and its involvement in the dynamics of B cells in the germinal center. Moreover, double immunofluorescence experiments demonstrated the co-expression of NFAT and cleaved-caspase 3 in apoptotic B cells of the germinal center. Thus, these results indicate that NFAT may participate in the regulation of B-cell dynamics such as apoptosis in the germinal center.
We report here an unusual autopsy case of bilateral adrenal lymphoma showing symptoms associated with hypercalcemia and taking a fulminant clinical course. The serum of the patient had a titer of 40pg/ml of intact parathyroid hormone (normal range: 10-65pg/ml) and a titer of 1720pmol/l of parathyroid hormone-related protein (PTHrP) (normal range: 13.8-55.3pmol/l). Autopsy revealed bilateral huge adrenal tumors, with the left weighing 230g, and measuring 12×9×3.5cm, and the right weighing 140g and measuring 11×8×3cm. Histological examination revealed that the adrenal tumors were diffuse large cell lymphoma, and that the neoplastic cells were positive for CD20 (L26) and CD79a (mb-1). In addition, the neoplastic cells were positive for PTHrP mostly in the perinuclear space of the cells. In addition to the coma associated with hypercalcemia and acute renal failure, congestion and bronchopneumonia developed, leading to the death of the patient. There have been three case reports of bilateral adrenal lymphoma associated with hypercalcemia. Hypercalcemia should be checked carefully in the cases with adrenal lymphoma because it may result in fulminant clinical course.
True histiocytic sarcoma (THS) is a rare form of malignant neoplasm, which is thought to have a poor prognosis. We report the case of a 47-year-old woman who presented with a solitary cutaneous tumor on the forehead. After excision of the tumor, she had no recurrence or metastasis for 10 years. Microscopic observation showed massive infiltration of histiocytoid tumor cells from the dermis without epidermotropism to the deep muscle layer. The large histiocytoid tumor cells contained folded nuclei with frequent mitoses and abundant cytoplasm, but showed no phagocytosis. Muscle fibers were destroyed by infiltration of the tumor cells. Immunohistochemically, the tumor cells were positive for histiocytic markers (CD68 and lysozyme), but negative for lymphoid and epithelial markers. No rearrangement of the immunoglobulin heavy chain and T-cell receptor β/γ chain genes was demonstrated. Therefore, the lesion was diagnosed as primary cutaneous true histiocytic sarcoma (PCTHS) based on the current, strict definition of histiocytic malignancies. In reviewing the literature, we found that some PCTHSs had an indolent clinical course; therefore, we propose that PCTHSs may have variable prognoses.