Cutaneous follicle center lymphomas with plasmacytic differentiation.

Follicle center lymphomas, including primary cutaneous follicle center lymphoma (PCFCL), may rarely show plasmacytic differentiation. Such cases can pose a diagnostic challenge and can be mistaken for other lymphomas that more commonly include plasma cells. Here, we report four cases of PCFCL and one case of systemic follicular lymphoma involving the skin with associated monotypic plasma cells, including the clinical, morphologic and immunophenotypic features.

Computer-assisted quantification of CD3+ T cells in follicular lymphoma.

The advance of high resolution digital scans of pathology slides allowed development of computer based image analysis algorithms that may help pathologists in IHC stains quantification. While very promising, these methods require further refinement before they are implemented in routine clinical setting. Particularly critical is to evaluate algorithm performance in a setting similar to current clinical practice. In this article, we present a pilot study that evaluates the use of a computerized cell quantification method in the clinical estimation of CD3 positive (CD3+) T cells in follicular lymphoma (FL). Our goal is to demonstrate the degree to which computerized quantification is comparable to the practice of estimation by a panel of expert pathologists. The computerized quantification method uses entropy based histogram thresholding to separate brown (CD3+) and blue (CD3-) regions after a color space transformation. A panel of four board-certified hematopathologists evaluated a database of 20 FL images using two different reading methods: visual estimation and manual marking of each CD3+ cell in the images. These image data and the readings provided a reference standard and the range of variability among readers. Sensitivity and specificity measures of the computer's segmentation of CD3+ and CD- T cell are recorded. For all four pathologists, mean sensitivity and specificity measures are 90.97 and 88.38%, respectively. The computerized quantification method agrees more with the manual cell marking as compared to the visual estimations. Statistical comparison between the computerized quantification method and the pathologist readings demonstrated good agreement with correlation coefficient values of 0.81 and 0.96 in terms of Lin's concordance correlation and Spearman's correlation coefficient, respectively. These values are higher than most of those calculated among the pathologists. In the future, the computerized quantification method may be used to investigate the relationship between the overall architectural pattern (i.e., interfollicular vs. follicular) and outcome measures (e.g., overall survival, and time to treatment). © 2017 International Society for Advancement of Cytometry.

Brefeldin A triggers apoptosis associated with mitochondrial breach and enhances HA14-1- and anti-Fas-mediated cell killing in follicular lymphoma cells.

Follicular lymphoma (FL) remains a fatal disease of increasing worldwide incidence. Since patients with FL eventually develop resistance to conventional anticancer agents, and due to BCL-2 overexpression present with profoundly compromised execution of mitochondrial pathway of apoptosis, targeting alternative pathways of cell demise may appear therapeutically beneficial. Herein we report for the first time the effects of an ER-Golgi transport inhibitor, Brefeldin A (BFA), alone and in combination with a small molecule Bcl-2 inhibitor HA14-1 or agonistic anti-Fas mAb, in the recently established human FL cell lines. All cell lines tested were sensitive to BFA-induced cytotoxicity and apoptosis. Moreover BFA-induced cell death was associated with profound ER stress, mitochondrial breach and subsequent caspase cascade activation, including caspase 2 activation. Interestingly, BFA-induced ER stress did not result in appearance of autophagic morphology in FL cells. Of importance, small molecule Bcl-2 antagonist, HA14-1 and agonistic anti-Fas mAb significantly enhanced BFA-mediated cytotoxicity and apoptosis, revealing novel and previously unexplored means to enhance ER stress-mediated cell killing in follicular lymphoma cells.

Differences in nuclear positioning of 1q12 pericentric heterochromatin in normal and tumor B lymphocytes with 1q rearrangements.

The frequent rearrangement of chromosome band 1q12 constitutive heterochromatin in hematologic malignancies suggests that this rearrangement plays an important pathogenetic role in these diseases. The oncogenic mechanisms linked to 1q12 heterochromatin are unknown. Constitutive heterochromatin can epigenetically regulate gene function through the formation of transcriptional-silencing compartments. Thus, as a first step toward understanding whether 1q12 rearrangements might compromise such activity in tumor cells, we investigated the 3-D organization of the 1q12 heterochromatin domain (1q12HcD) in normal and tumor B lymphocytes. Strikingly, in normal B cells, we showed that the 1q12HcD dynamically organizes to the nuclear periphery in response to B-cell receptor engagement. Specifically, we observed an almost twofold increase in 1q12Hc domains at the extreme nuclear periphery in activated versus resting B lymphocytes. Remarkably, 1q12Hc organization was noticeably altered in tumor cells that showed structural alterations of 1q12; the 1q12Hc domains were significantly displaced from the extreme nuclear periphery compared to normal activated B lymphocytes (P > 0.0001), although overall peripheral localization was maintained. In a case in which there was a translocation of IGL enhancer to 1q, the altered nuclear positioning of the 1q12HcD was even more pronounced (5% of the 1q12Hc domains at the nuclear periphery compared to 20% in other lymphoma lines), and we were able to mimic this effect in two additional B-cell tumor lines by treatment with trichostatin A, a histone deacetylase (HDAC) inhibitor. Taken together, these results point to the 1q12HcD having a specific, nonrandom, and regulated peripheral organization in B lymphocytes. This organization is significantly disrupted in lymphoma cells harboring 1q rearrangements.

A new method to extract nuclei from paraffin-embedded tissue to study lymphomas using interphase fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) is difficult to accomplish using thin-sections of paraffin-embedded lymphoid tissue because of the high cellularity and truncated cells that interfere with accurate scoring of individual nuclei. We modified and tested a new technique to isolate individual nuclei from tissue cores of paraffin-embedded tissue processed with xylene, proteinase K, citric acid, and pepsin. The efficacy of this method to study paraffin-embedded tissue was investigated in six normal lymph nodes or tonsils and 32 malignant lymphomas including five mantle cell, five follicular, five Burkitt, five extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue, five anaplastic large-cell, and seven diffuse large B-cell. Fusion of CCND1 and IgH, BCL2 and IgH, c-myc and IgH, and MALT1 and API2 were detected using probes with a dual-fusion FISH strategy. Anomalies involving ALK and BCL6 were detected using break-apart FISH probes. FISH studies were successful for each of the 38 specimens. Chromosome anomalies were detected in each malignant specimen, but not in the normal lymphoid tissue. The correct chromosome anomaly was detected in 22 of 22 specimens with genetic abnormalities that were established by other genetic techniques. This FISH technique is useful to detect chromosome anomalies with high sensitivity and specificity in paraffin-embedded tissue and may provide important diagnostic and prognostic genetic information.

A new in vivo and in vitro B cell lymphoma model, pi-BCL1.

We report a new variant of the BCL1 syngeneic mouse B-cell lymphoma model, which we have called pi-BCL1. pi-BCL1 can be established as a syngeneic tumor in BALB/c mice. Tumors can be removed, prepared and easily grown in liquid culture and subsequently transferred back successfully as syngeneic tumors. As a syngeneic tumor pi-BCL1 behave more like a lymphoma with solid tumor masses, than a chronic lymphocytic leukaemia of the original BCL1 model. The immunophenotype and the growth characteristics of the pi-BCL1 and BCL1 tumors appear very similar. Cytologically, pi-BCL1 appears to be a transformation from a small lymphocytic lymphoma to a more diffuse large cell centroblast-like higher-grade lymphoma. We are not aware of any previous reports of such transformation events in a syngeneic animal model of B cell lymphoma. We believe pi-BCL1 provides a useful new tool for the study of B cell lymphoma in vitro and in vivo and enables reduced numbers of tumor passage in mice.

Follicular dendritic cell tumor: report of 13 additional cases of a distinctive entity.

Follicular dendritic cell (FDC) tumor is an extremely rare malignant neoplasm with approximately 17 well-documented cases in the literature. We report 13 additional cases of this distinctive neoplasm. There were seven men and six women, with a mean age of 46.5 years (range, 27-62 years). There was involvement of cervical lymph nodes (six cases), mediastinum (three cases), axilla, tonsil, spleen, and peripancreatic soft tissues (one case each). The neoplasms were grey to tan, ranging in size from 1 to 13 cm. They were formed by oval to spindle cells with eosinophilic cytoplasm growing in sheets and fascicles, with a focal storiform pattern and whorls reminiscent of those seen in meningioma. The nuclei were oval or elongated with thin nuclear membranes, inconspicuous or small eosinophilic nucleoli, and clear or dispersed chromatin. Typically, the tumor cells were intimately admixed with small lymphocytes, with a prominent perivascular cuffing. Multinucleated tumor cells were present in seven cases. Necrosis, marked cellular atypia, high mitotic rate, and/or abnormal mitoses were present in seven cases. The tumor cells were positive for CD21 (10 of 11), CD35 (10 of 11), Ki-M4p (seven of eight) Ki-FDRC1p (six of seven), vimentin (five of nine), and S100 protein (five of nine). One case stained with actin. In situ hybridization, done in six cases, did not show Epstein-Barr virus RNA sequences. Ultrastructural examination of eight cases showed long, complex, occasionally interdigitating cytoplasmic processes joined by desmosomes. The behavior of these tumors is more akin to that of a low-grade soft tissue sarcoma than a malignant lymphoma and is characterized by local recurrences and occasional metastases. Two patients died of tumor, two were alive with recurrent or metastatic disease, eight were alive with no disease, and one was lost to follow-up.

True histiocytic lymphoma with multiple skin nodules.

A 73-year-old white woman developed multiple cutaneous nodules that fluctuated in size and occasionally regressed. The tumor cells infiltrating the dermis were histiocytic by light microscopy, marker studies, and electron microscopy. Similar cells were present in a bone marrow biopsy specimen. A diagnosis of true histiocytic lymphoma was made. The case illustrates some of the problems that may arise in evaluation of clinical and pathologic findings in a patient with a proliferative disorder of histiocytes and demonstrates the contribution that electron microscopy can provide in establishing the diagnosis.

Distinction between diffuse cutaneous malignant follicular center cell lymphoma and lymphoid hyperplasia by computerized nuclear image analysis.

The difficult differential diagnosis between the diffuse variants of cutaneous lymphoid hyperplasia (CLH; synonym; pseudolymphoma) and malignant follicular center cell lymphomas (FCCL) often requires a multidisciplinary approach. Eighteen CLH and 11 FCCL, diagnosed by conventional histology and immunophenotyping and subsequently examined with a polymerase chain reaction to show clonal immunoglobulin heavy-chain gene rearrangements, were subjected to a novel type of automated nuclear image analysis. Of all nuclear parameters tested in azure A-stained semithin sections, the mean nuclear profile area (TN) of lymphoid cells was the best criterion to distinguish between CLH and FCCL (p = 9 x 10(-6)). Additional distinctive features, in the order of decreasing significance, were the SD of TN; all chromatin textural parameters combined; and the light and the dark fractions of the central nuclear profile areas. Parameters related to the chromatin pattern were independent of nuclear profile size in FCCL, but not in CLH. Two lesions registered as CLH displayed the nuclear characteristics favoring this diagnosis, but showed B-cell monoclonality at the DNA level. In conclusion, computerized nuclear image analysis is a helpful additional diagnostic tool in the evaluation of diffuse CLH and cutaneous FCCL.

Reduced apoptotic cell death in follicular lymphoma.

It has been hypothesized that inhibition of germinal centre cell apoptosis may underlie the development of follicle centre cell lymphomas. We have performed a comparative, quantitative study of apoptotic cell death in germinal centres and in the neoplastic follicles of centroblastic-centrocytic, follicular, non-Hodgkin's lymphoma (Cb/Cc NHL). Ten cases each of reactive follicular hyperplasia and Cb/Cc NHL were analysed. One-micrometre-thick resin-embedded sections were examined at x 1000 magnification. The total numbers of cells, nuclear containing apoptotic bodies, and mitoses were counted in each follicle and the apoptotic and mitotic indices were derived. Transmission electron microscopy was performed on selected cases to confirm the typical features of apoptosis. The mean apoptotic (4.9 per cent) and mitotic indices (0.9 per cent) for the germinal centres were significantly higher (P much less than 0.001) than those for the neoplastic follicles (0.9 and 0.14 per cent). These results lend support to the recent proposal that reduced apoptotic cell death may be important in the pathogenesis of follicular lymphomas.

Genotypic characterization of centrocytic lymphoma: frequent rearrangement of the chromosome 11 bcl-1 locus.

Centrocytic lymphomas are defined in the Kiel classification as B-cell lymphomas composed exclusively of cells resembling cleaved follicular center cells (FCC). These lymphomas have been shown to be histologically, immunophenotypically, and clinically distinct from other cleaved FCC lymphomas. DNA from 18 centrocytic lymphomas (14 patients) was analyzed using Southern blotting and probes for immunoglobulin heavy (JH) and kappa light chain (JK) joining gene, T-cell receptor beta chain constant gene (CB), bcl-1, bcl-2, and c-myc gene rearrangements. All of the lymphomas had JH and JK rearrangements, confirming their B-cell origin. None of the specimens had detectable CB, bcl-2, or c-myc rearrangements. However, 4 of 14 patients (28.6%) had rearrangement of the chromosome 11 bcl-1 locus. Therefore, centrocytic lymphomas are genotypically distinguishable from the majority of other small cleaved FCC lymphomas by their lack of demonstrable bcl-2 rearrangements. This supports the distinct nature of centrocytic lymphomas and suggests the lack of importance for the putative oncogene bcl-2 in these cases. Furthermore, the frequent rearrangement of bcl-1 suggests a possible role for this locus in the pathogenesis of at least some centrocytic lymphomas.

Cleaved and multilobated cell immunocytoma of low grade malignancy with amyloid. An immunohistochemical and electron microscopical study.

An unusual variant of immunocytoma of low grade malignancy, cytologically resembling follicular cleaved-cell malignant lymphoma is described. Presence of heavy deposits of amyloid, intracytoplasmic monoclonal IgM-kappa immunoglobulin, cells with Dutcher inclusions, electron-microscopic features and negativity of T-cell markers led to diagnosis of immunocytoma. After cytostatic chemotherapy the lymphoma changed its morphology into typical lymphoplasmacytoid immunocytoma.

Morphological and immunohistochemical investigation of non-Hodgkin's lymphoma combined with Hodgkin's disease.

Twenty cases with a morphological picture highly suspicious for a combination of non-Hodgkin's lymphoma and Hodgkin's disease were investigated. The infiltrates of Hodgkin's disease differed from those of non-Hodgkin's lymphoma in their cellular component of Hodgkin and Sternberg-Reed cells and the irregularity in the fibre pattern. Based upon histological and immunohistochemical criteria the 20 cases were divided into three groups. Group 1 (n = 10) contained seven chronic lymphocytic leukaemias of B type, one lymphoplasmacytoid immunocytoma, and two centroblastic/centrocytic lymphomas. The non-Hodgkin's lymphoma components showed a monotypic immunoglobulin distribution pattern and/or leukaemic blood picture. Adjacent to the non-Hodgkin's lymphoma was typical Hodgkin's disease in which Hodgkin and Sternberg-Reed cells were positive for both immunoglobulin light chains and IgG and reacted with anti-CD15. Group 2 (n = 5) consisted exclusively of centroblastic/centrocytic lymphoma in combination with Hodgkin's disease in which the few Hodgkin and Sternberg-Reed cells were negative with anti-CD15 monoclonal antibody. Group 3 (n = 5) consisted of four chronic lymphocytic leukaemias of B type and one lymphoplasmacytoid immunocytoma. In these cases no combination with Hodgkin's disease could be diagnosed apart from the presence of partially CD15 positive Hodgkin and Sternberg-Reed cells. The following conclusions were drawn: anti-CD15 (LeuM1 and 3C4/C3D-1) can neither confirm nor exclude Hodgkin's disease since, while they do not detect Hodgkin and Sternberg-Reed cells in all cases of Hodgkin's disease, they do recognize Hodgkin and Sternberg-Reed cells in some B-cell lymphomas; anti-CD30 (Ber-H2) reacted with Hodgkin and Sternberg-Reed cells in all cases of Hodgkin's disease and also detected these cells in cases of non-Hodgkin's lymphoma.

Morphology and immunology of circulating cells in leukaemic phase of follicular lymphoma.

Ten patients with follicular lymphoma presented with a high white cell count (45-220 x 10(9)/l) which resembled chronic lymphocytic leukaemia (CCL): all had pronounced splenomegaly and, except one, generalised lymphadenopathy. The blood lymphocytes were small with scanty cytoplasm, densely condensed nuclear chromatin, and deep clefts originating in sharp angles from the nuclear surface. CLL cells are larger, have more cytoplasm, a different pattern of chromatin condensation, and may have shallow nuclear indentations or foldings rather than clefts. The circulating follicular lymphoma cells had moderate to strong membrane immunoglobulins (SmIg), low mouse (M)-rosettes, strong reactivity with the monoclonal antibody FMC7, and occasional expression of the CD5-antigen; at least one third of cells in each case were positive with anti-cALLa (J5,CD10). Half the cases were referred as B-CLL but none had the typical B-CLL immunophenotype: weak SmIg, M-rosettes of greater than 50%, CD5 positive, FMC7 and J5 negative. The diagnosis of follicular lymphoma was confirmed by lymph node biopsy in seven of the 10 cases. The overall response to treatment was poor and five patients died within three years of diagnosis. This aggressive form of follicular lymphoma needs to be distinguished from B-CLL as different management is required.

The extracellular matrix in "sclerosing" follicular center cell lymphomas: an immunohistochemical and ultrastructural study.

"Sclerosis" is frequently seen in follicular center cell (FCC) lymphomas. The mechanism of its deposition, as well as its composition and significance, are unknown. Several clinical studies have suggested that the course of these lymphomas is more indolent than that of lymphomas of the same histologic type without sclerosis. Nine immunologically characterized cleaved FCC lymphomas with sclerosis and 14 reactive lymph nodes with follicular hyperplasia were investigated by special staining methods, electron microscopy, and immunohistochemical studies with antibodies to types I, III, IV, and V collagen, laminin, and fibronectin. The sclerotic tissue in FCC lymphomas stained uniformly with periodic acid-Schiff (PAS) and Masson's stain, with the patterns ranging from delicate filamentous strands to dense doubly refractile bands. Ultrastructurally, the bands of connective tissue were continuous with the adventitia of vessels and composed of varying amounts of banded collagen (types I and III) admixed with filamentous and flocculent material. In all cases the neoplastic lymphocytes were separated from the extra-cellular matrix by fibroblasts and myofibroblasts with long cell processes. Immunohistochemical studies demonstrated intense staining of sclerotic bands with antibodies to fibronectin and type I collagen and, usually, weaker marking with antibodies to types III and V collagen. No significant staining of sclerotic bands was found with antibodies to type IV collagen or with laminin. Weak pericellular staining for type V collagen was present in eight of nine lymphomas and half of the control lymph nodes. These studies suggest that the increased amounts of extracellular matrix in cleaved FCC lymphomas are produced primarily by fibroblasts and myofibroblasts and represent predominantly fibronectin and types I, III, and V collagen. The composition of the sclerotic areas of FCC lymphomas is similar immunohistochemically to that of the capsule and trabeculae of reactive lymph nodes, which are also intimately associated with fibroblasts and myofibroblasts.

Mantle-zone lymphoma. A pattern produced by lymphomas of more than one cell type.

We analyzed the distribution and immunologic phenotype of the neoplastic cells in eight cases of mantle-zone lymphoma. Although in all the cases the follicle centers appeared reactive on routine histologic examination, polyclonal staining for immunoglobulin was found in the follicle centers in only five of the eight cases; in the other three cases the follicle centers were monoclonal. In three cases, the immunologic phenotype was that of centrocytic (diffuse small cleaved cell) lymphoma: IgM+IgD+B1+B2+Ia+Tl+. In one case the phenotype was that of a follicular (centroblastic/centrocytic) lymphoma: IgG+B1+B2+Ia+CALLA+. In the other four cases, the phenotype was IgM+B1+B2+ or B2-Ia+; this phenotype can be seen in diverse B cell lymphomas. The phenotype of normal mantle-zone cells (IgM+IgD+B1+B2+Ia+) was not reproduced by any of the lymphomas. A mantle-zone pattern may be produced by either follicular or diffuse lymphomas of predominantly small cleaved cell type, and does not indicate an origin from the cells of the normal mantle zone.

A case of swine follicular lymphoma with intracytoplasmic immunoglobulin inclusions.

A case of swine follicular lymphoma with Russell body-type inclusions is described in a 4-year-old pig. Distinct neoplastic follicles were observed in various lymph nodes and contained many cells with Russell body-type inclusions that were positive for IgM and corresponded to dilated cisternae of the RER. Desmosome-connected dendritic reticulum cells and neoplastic cells with desmosome-like structures demonstrated the germinal centre origin of this tumour. Although such cases have been reported in man, this is the first recorded case of swine follicular lymphoma showing this feature. The histological similarity of swine follicular lymphoma with Russell body-type inclusions to that of man is discussed, as is the relationship between reactive follicular hyperplasia and follicular lymphoma.