The lymphoblastic lymphoma: a clinical and morphological entity, two new cases

There are reported two new cases of lymphoblastic lymphoma in an 8 and a 12 year-old child respectively. The diagnosis is based on cytological features, similar or identical to those of acute lymphoblastic leukemia, the presence of a mediastinal growth and a rapid evolution, and with an early involvement of the bone marrow. The cytohistological pattern was dominated in one case by the proliferation of immature lymphocytes with convoluted nuclei, and in the second one by immature lymphocytes with round nuclei. The T cell origin of these lymphomas and the practical value of their recognition for an early treatment are discussed.     

Nodal presentation of nasal-type NK/T-cell lymphoma. Report of two cases with fine needle aspiration cytology findings

BACKGROUND: Epstein-Barr virus (EBV)-associated NK/T-cell lymphoma typically occurs in extranodal sites, such as nasal cavity, nasopharynx, gastrointestinal tract, skin, testis and salivary gland. Secondary lymph node involvement is rarely encountered until late in the disease course. The fine needle aspiration cytology of NK/T-cell lymphoma with a nodal presentation has not been described before. CASES: Two cases of nasal-type (extranasal) NK/T-cell lymphoma with a nodal presentation were seen at Pamela Youde Nethersole Eastern Hospital, Hong Kong. Both patients presented with submandibular lymph node enlargement but unremarkable peripheral blood and bone marrow findings. Fine needle aspiration cytology was available in both cases, showing a heterogeneous population of small to medium-sized lymphoid cells, follicular center cells, plasma cells, eosinophils and some histiocytes. The medium-sized lymphoid cells showed readily discernible nuclear atypia with an irregular nuclear outline. Cell block sections revealed occasional lymphoid cells with pleomorphic nuclei. Immunocytochemical study confirmed the presence of CD56-positive lymphoma cells. In situ hybridization for EBV-encoded RNA also revealed positive nuclear signals. Histologic examination of the surgical biopsies showed interfollicular expansion by malignant lymphoid cells. Immunoglobulin heavy chain gene and T-cell receptor gene rearrangement studies demonstrated a germline pattern, confirming the putative NK (natural killer cell), non-B and non-T lineage of the lymphoma cells. CONCLUSION: Nodal presentation of NK/T-cell lymphoma, though rare, is diagnosable on the basis of fine needle aspiration biopsy alone, especially in view of its distinctive immunophenotype and EBV association. Recognition of the subtle but definite cytologic atypia of malignant lymphoid cells and presence of an appropriate background (including more eosinophils than usual), together with proper application of ancillary techniques, is crucial to arriving at a correct diagnosis.     

Alveolar rhabdomyosarcoma of the vulva. Report of two cases

The cytologic and histologic findings in two cases of the extremely rare alveolar rhabdomyosarcoma of the vulva are reported. The tumor cells in fine needle aspiration smears from one case and tumor imprints from both cases were isolated or were in sheets or reticular patterns. The nuclei were round to oval; only a few cells were multinucleated. The chromatinic material was increased in amount and finely granular. Many mitotic figures were observed. The cytoplasm was scanty in general, but some cells had abundant cytoplasm; cross striations were not recognized. The tumor cells were positive with immunocytochemical stains for desmin, vimentin and myoglobin. Similar findings were observed in biopsy and surgical specimens.     

Epstein-barr virus regulates c-MYC, apoptosis, and tumorigenicity in Burkitt lymphoma

Loss of the Epstein-Barr virus (EBV) genome from Akata Burkitt lymphoma (BL) cells is coincident with a loss of malignant phenotype, despite the fact that Akata and other EBV-positive BL cells express a restricted set of EBV gene products (type I latency) that are not known to overtly affect cell growth. Here we demonstrate that reestablishment of type I latency in EBV-negative Akata cells restores tumorigenicity and that tumorigenic potential correlates with an increased resistance to apoptosis under growth-limiting conditions. The antiapoptotic effect of EBV was associated with a higher level of Bcl-2 expression and an EBV-dependent decrease in steady-state levels of c-MYC protein. Although the EBV EBNA-1 protein is expressed in all EBV-associated tumors and is reported to have oncogenic potential, enforced expression of EBNA-1 alone in EBV-negative Akata cells failed to restore tumorigenicity or EBV-dependent down-regulation of c-MYC. These data provide direct evidence that EBV contributes to the tumorigenic potential of Burkitt lymphoma and suggest a novel model whereby a restricted latency program of EBV promotes B-cell survival, and thus virus persistence within an immune host, by selectively targeting the expression of c-MYC.     

Hematoidin crystals in cervicovaginal smears. Report of two cases

Cervicovaginal smears obtained from two women, one at the 32nd week of pregnancy and the other at the immediate postpartum period, contained hematoidin crystals. These crystals were of a golden color and appeared as radially arranged fine needles forming cockleburrs or as aggregates of small irregular particles, spherules or rhomboids, in most instances associated with or within histiocytes. Hemosiderin pigment was associated with them in small amounts. The presence of hematoidin crystals is not an uncommon finding in cytologic specimens, particularly those obtained by fine needle aspiration of walled-off, necrotizing lesions with a component of hemorrhage. It is a very unusual finding in cervicovaginal smears, probably because of the ability of the uterus to promptly rid itself of blood. Certain aspects of the formation and identity of hematoidin are discussed.     

Cytologic findings in progressive multifocal leukoencephalopathy. Report of two cases

Cytologic preparations from two cases of progressive multifocal leukoencephalopathy (PML) were obtained by stereotactically guided needle biopsies using computerized tomograms of the brain. Case 1 was a 32-year-old man with an acquired immunodeficiency syndrome-related complex. Case 2 was a 71-year-old man with chronic lymphocytic leukemia. Smears showed moderate cellularity, consisting of moderately to markedly atypical cells with enlarged hyperchromatic nuclei. The chromatin pattern showed smudging, with or without clumping, similar in pattern to the human polyomavirus-infected "decoy" cells seen in urine cytology. Nuclei were predominantly round to oval, smoothly contoured and often stripped of cytoplasm. Occasional bizarre lobulated or multinucleated forms were seen. Some atypical cells had abundant cytoplasm exhibiting stellate projections. Histologic sections of the biopsy material confirmed the diagnosis in each case. In both cases, electron microscopy demonstrated intranuclear polyoma-type virus particles. The present findings suggest that PML should be considered in the differential diagnosis of marked cytologic atypia in brain aspirates from immunocompromised patients.     

Interferon-mediated intracellular signalling. Modulation of different phospholipase activities in Burkitt lymphoma cells.

The effect of interferon-alpha on Daudi lymphoma cells either sensitive or resistant to the action of this cytokine has been analysed in terms of phospholipase C (PLC) and D (PLD) activities. Results have shown a combined modulation of PIP2-specific phospholipase C and phospholipase D. In particular, a decreased activity of PIP2-specific PLC has been found, concomitant to a PLD-mediated phosphatidylcholine hydrolysis, suggesting that the intracellular signalling activated by interferon in Daudi cells involves a phospholipase D/phosphohydrolase pathway.     

Caspase-independent killing of Burkitt lymphoma cell lines by rituximab

Caspase-independent cell death may have a critical role to play in the therapeutic destruction of tumours. Recently it has been suggested that one of the mechanisms by which rituximab, a therapeutic anti-CD20 antibody, kills B cells is caspase-independent. In this study we show that rituximab can induce death in a variety of Burkitt lymphoma derived cell lines. Rituximab-treated cells show leakage of adenylate kinase, surface expression of phosphatidylserine, upregulation of the cellular stress protein HSP70, phosphorylation of the survival protein Akt, and depolarisation of the mitochondrial membrane but no loss of cytochrome c or apoptosis inducing factor. Caspase inhibitors do not block these events. In support of these data there is no cleavage of caspases 3, 8 and 9, poly(ADP-ribose) polymerase, BH3 interacting domain death agonist or genomic DNA. Morphologically, cells show nuclear enlargement and cytoplasmic vacuolisation. Triggering of receptor mediated death in CD95 responsive lines results in “classical” apoptosis indicating that the internal machinery necessary for apoptosis is intact in these lines. The results suggest that rituximab can kill human B cells via a caspase-independent form of programmed cell death that shares features of apoptosis and necrosis. This pathway may be relevant to the clinical efficacy of rituximab.