Reactive Infiltrate Research Articles

CD8-Positive Primary Cutaneous Anaplastic Large T-Cell Lymphoma (PCALCL): Case Report and Review of This Unusual Variant of PCALCL

Primary cutaneous anaplastic large T-cell lymphoma (PCALCL) is a well-defined CD30-positive lymphoproliferative disorder with relatively good prognosis and response to treatment. We describe a case of PCALCL expressing CD8. The patient is a 57-year-old man that clinically presented with an ulcerated nodule in his left middle finger. Histopathologic sections showed an ulcerated epidermis with a diffuse lymphocytic infiltrate in the superficial dermis with focal epidermotropism. The large cohesive atypical cells were admixed with a reactive infiltrate composed of neutrophils, eosinophils, and small lymphocytes. Immunohistochemical studies showed the tumor cells to be strongly positive for CD8, CD30, and TIA-1, focally positive for CD3, and negative for CD4, CD20, CD56, Anaplastic Lymphoma Kinase (ALK-1), and HSV. Epstein-Barr virus by in situ hybridization was negative. The diagnosis of a CD8+ PCALCL was confirmed. There is limited precedent literature regarding CD8-positive PCALCL and this case falls within the clinical and histopathologic spectrum of CD30+ lymphoproliferative disorders. CD8/CD30 coexpression is rare in PCALCL and may have important clinical and prognostic implications. To the best of our knowledge there are only 4 previously reported cases describing similar findings.

B-cell Lymphofollicular Infiltrates in Mycosis Fungoides

The histopathological picture of mycosis fungoides can be characterized by heavy reactive infiltrates. These are rarely composed of B lymphocytes with formation of reactive follicles. We collected three cases of mycosis fungoides with a reactive B-cell lymphofollicular reaction at the bottom of the epidermotropic infiltrate. Case 1 showed flat lesions (patches) with a CD4+ neoplastic phenotype; case 2 presented infiltrated lesions (plaques) with a CD8+ immonophenotype; case 3 was characterized by nodular lesions (tumors) with a CD4+ neoplastic component. In all three cases, no clonal gene rearrangement was found with the polymerase chain reaction technique. Among the protean clinicopathological features which mycosis fungoides can show, we underline that a B-cell lymphofollicular component can be encountered at the base of the epidermotropic infiltrate even in clinically flat ("patchy") lesions.

Induction of monocyte chemoattractant protein-1 (MCP-1/CCL2) gene expression by human immunodeficiency virus-1 Tat in human astrocytes is CDK9 dependent

Human immunodeficiency virus-1 (HIV-1) invades the brain early in infection and may cause HIV-associated dementia (HAD), which is characterized by reactive astrocytes, and macrophage and T-cell infiltrates. HIV-1 Tat protein is thought to contribute to HAD by transactivating host genes, such as that encoding monocyte chemoattractant protein-1 (MCP-1/CCL2), although its mechanisms of action are not fully understood. We investigated the molecular pathways involved in Tat-induced MCP-1/CCL2 gene expression in human astrocytes. We found that Tat induced MCP-1/CCL2 synthesis in human astrocytes infected with a lentivirus carrying the gene encoding Tat or treated with a biologically active synthetic Tat protein. The induction of MCP-1/CCL2 was independent of the nuclear factor kappaB (NF-kappaB) classical pathway, but was significantly inhibited by specific cyclin-dependent kinase 9 (cdk9) inhibitors, such as a dominant-negative mutant or siRNA. By contrast, broader-spectrum cdk inhibitors, such as roscovitine, 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole (DRB), and flavopiridol, inhibited MCP-1/CCL2 induction by Tat. We also analyzed the effects of roscovitine, DRB, and flavopiridol on Tat-induced HIV-1 long terminal repeat (LTR) expression following the infection of astrocytes and HeLa cells. Astrocytes showed no inhibition by roscovitine, 59% inhibition by DRB, and 80% inhibition by flavopiridol. In control HeLa cells, high levels of inhibition were observed with roscovitine, DRB, and flavopiridol. We have ascertained the direct implication of cdk9 in Tat-induced MCP-1 expression by performing ChIP assay. These results demonstrate that cdk9 is involved in Tat-induced HIV-1 LTR, MCP-1/CCL2 gene expression.

Lymphomas in the bone marrow

Lymphomatous infiltrates are most commonly encountered in a bone marrow biopsy (BMB) taken for lymphoma staging or for diagnosis of a suspected haematological abnormality. Crucial for staging, the BMB may show classic and variant patterns of lymphomatous infiltration and immunoprofile. Exceptions to the common profiles may be associated with variant cytogenetics and have prognostic implications. Diagnosis should be multifaceted and flow cytometry and molecular studies may be required to arrive at a final diagnosis. Assessment of haematopoiesis should be included in all reports. In follow-up biopsies, disease bulk may be markedly reduced and reactive lymphoid proliferation may complicate the morphological assessment. Transformation of the original lymphoma to a higher grade or the development of a new type of lymphoma may occur or the BMB may be discordant with the lymph node diagnosis. Plasma cell myeloma and related disorders must be considered in the differential diagnosis of lymphoid proliferations with plasmacytic and plasmablastic differentiation. Diffuse interstitial lymphocytosis, lymphoid aggregates, lymphoid follicles with germinal centres and reactive lymphohistiocytic infiltrates may mimic lymphomas.

Dense lymphocytic infiltrates associated with non-melanoma skin cancer in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a common hematologic malignancy associated with an increased risk of non-melanoma skin cancer. Basal cell carcinomas and squamous cell carcinomas in these patients may have an associated dense peritumoral leukemic infiltrate. This infiltrate can lead to the diagnosis of CLL and may also obscure tumor margins and pose a challenge in the assessment of perineural tumor spread. Immunohistochemical stains are useful in distinguishing leukemic B-cell infiltrates from tumor-reactive T-cell infiltrates. Leukemic cells of CLL are CD20+/CD23+/CD5+/CD43+/CD3-, whereas benign reactive infiltrates are composed of CD20-/CD23-/CD5+/CD43+/CD3+ T-cells. Given the paucity of symptoms in early stages of CLL, a dense lymphoid infiltrate surrounding a cutaneous neoplasm may serve as the first indication of CLL. We report a series of three cases of SCC with a coexisting infiltrate of CLL, including one with perineural involvement, one involving metastatic SCC, and one in which this histologic finding spurred the initial diagnosis of CLL.

Extranodal lymphomas

The assessment of extranodal lymphomas poses considerable challenges to general surgical histopathologists and specialist haematopathologists alike. The breadth of lymphoma subtypes that may occur at extranodal sites, the variation in morphology, immunophenotype, genetics and clinical features within and between these entities, the difficulties in distinguishing these lymphomas from reactive lymphoid infiltrates or other neoplasms, and the different clinical significance of lymphomas with primary versus secondary involvement of extranodal sites, all contribute to these challenges. In this review, I will discuss several lymphomas defined by extranodal origin (in particular extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue/MALT lymphoma, and enteropathy-associated T cell lymphoma) and aspects of selected others likely to be encountered at extranodal sites, with an emphasis on practical histopathological assessment. Lymphomas of the spleen, skin, bone marrow and thymus are not covered, as these are comprehensively reviewed in companion articles.

Improved Polymerase Chain Reaction–Based Method to Detect Early-Stage Epitheliotropic T-Cell Lymphoma (Mycosis Fungoides) in Formalin-Fixed, Paraffin-Embedded Skin Biopsy Specimens of the Dog

In the dog, early-stage epitheliotropic T-cell lymphoma (ETCL) can clinically and histologically mimic a large range of inflammatory dermatoses and often progresses rapidly to a more aggressive tumor stage. Early diagnosis of ETCL is essential to proceed with a specific oncologic therapy that is favorable for the prognosis. In the present study, an improved method for the detection of T-cell receptor gamma (TCRgamma) rearrangement was developed by designing a new set of consensus primers to amplify the different forms of rearranged canine TCRgamma gene sequences by polymerase chain reaction. The amplicons were analyzed by conventional polyacrylamide gel electrophoresis, which requires minimal specific equipment and may be performed in almost every pathology laboratory at low costs. The method proved to be highly specific and sensitive to detect early ETCL in formalin-fixed, paraffin-embedded biopsy specimens, providing an efficient tool for veterinary pathologists to distinguish early neoplastic from reactive cutaneous T-cell infiltrates (tumor-specific marker) or to discriminate T-cell lymphoma from B-cell lymphomas or nonlymphoid neoplasms (T-cell lineage marker). By direct sequencing analysis of amplified TCRgamma gene sequences, ETCL was found to rearrange exclusively the joining (J) 4 region, which suggests specific biology for primary cutaneous T-cell lymphomas. Also, a novel (seventh) functional J region in the TCRgamma gene, localized approximately 2.3 kb upstream of J5, was identified.

Cutaneous presentation of ALK-positive anaplastic large cell lymphoma following insect bites: evidence for an association in five cases

Skin involvement is frequent in ALK-positive anaplastic large cell lymphomas. The role of an insect bite as a triggering event has been postulated but not well documented. We retrospectively investigated five cases of ALK-positive anaplastic large cell lymphoma who presented with skin lesions occurring after an insect bite. Biopsies were immunostained with antibodies against CD30, ALK, T- and B-cell antigens. Persistent skin lesions developed after solitary insect bites in three patients and after multiple bites in two. Regional lymphadenopathy developed within weeks after the bite in three cases. In four cases the correct diagnosis was delayed due to misinterpretation of the findings as a reactive infiltrate in the skin (n=2) or lymph nodes (n=2); all cases subsequently showed small numbers of cells with nuclear and cytoplasmic staining for ALK. The final diagnoses were lymphohistiocytic variant (n=3) and composite common/small cell type (n=2) anaplastic large cell lymphoma. The patients were treated and three were alive at the last follow-up. Two patients died, one of pneumonia and the other of disseminated disease. In these cases the sequence of events between the insect bites and the occurrence of both skin lesions and satellite lymphadenopathy suggest a direct relationship between the bite and the presentation with anaplastic large cell lymphoma. We postulate that insect bite-associated antigens could result in an influx of T lymphocytes, some bearing the t(2;5). The subsequent release of cytokines at the site of the bite could act as a 'second hit', eliciting activation of the latter cells, which would then express the oncogenic NPM-ALK protein and undergo uncontrolled proliferation.

Serum TARC Levels Correspond with Tumor Load and Response to Chemotherapy in Classical Hodgkin Lymphoma Patients.

Abstract 3663Poster Board III-599 IntroductionThymus and Activation Related Chemokine (TARC) is produced in high amounts by Hodgkin and Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL). It attracts CCR4 positive Th2 and Treg cells, which are typically present in large numbers in the reactive infiltrate in cHL. TARC can be measured in the serum of cHL patients and is usually elevated in the presence of active disease, as compared to healthy controls. Higher levels are observed in advanced stage disease, compared to stage I disease. The goal of the current study was to correlate TARC serum levels to metabolic response to therapy as measured by FDG-PET scanning. Patients and methodsNewly diagnosed cHL patients treated in our hospital were asked to participate. Serum samples were taken before the start of treatment, at the time of the mid treatment PET scan (after 2 cycles of ABVD for stage I and II, or mid BEACOPP or ABVD treatment for stage III and IV disease) and at the time of the PET scan after completion of chemotherapy. TARC serum levels were measured by ELISA and TARC immunohistochemistry was done on primary involved lymph node tissue. ResultsA total of 59 cHL patients, median age 40 (range 16-80) and 49% male participated. Eight patients had stage I, 26 stage II, 14 stage III and 10 stage IV disease. The known association of high pretreatment TARC levels with advanced stage was also significantly present in our data, supporting the hypothesis that serum TARC levels reflect tumor burden. Moreover, in stage I and II patients, bulky disease (27%) was associated with a significant higher TARC level, lending further support to this hypothesis. Compared to pretreatment values, TARC levels had decreased significantly at mid treatment and treatment completion to the range of healthy controls. Only in stage I there was no significant difference between pretreatment and mid or after treatment samples (see figure), probably due to the relatively large number of patients without elevated TARC before the start of therapy. In patients with a positive PET scan at mid treatment (26%), there was a trend for a higher TARC level (P=0.08) compared to PET negative patients. After completion of chemotherapy PET positivity (19%) was significantly associated with a higher TARC level. Three patients had a relapse and at that time TARC levels had clearly increased in comparison to the levels after treatment. Conclusionsserum TARC levels are associated with tumor burden and metabolic response to therapy as measured by FDG-PET scan. Measurement of serum TARC levels is a potential tool to evaluate the response to therapy and to be used in follow up after completion of chemotherapy. Inclusion of more patients is necessary to further assess the clinical value of TARC serum levels and is ongoing. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Indolent cutaneous T‐cell lymphoma presenting as cutaneous lymphocytosis in dogs

Cutaneous lymphoproliferative diseases encompass a spectrum of lesions, ranging from self-limiting, reactive infiltrates to high-grade lymphomas. In humans, cutaneous lymphocytosis (CL) refers to self-limiting or slowly progressive monomorphic lymphocytic infiltrates of mostly unknown cause. It morphologically mimics cutaneous lymphoma. CL in cats also is a slowly progressive disease. Immunophenotyping and clonality testing of feline CL support an indolent lymphoma for the majority of cases studied. This study reports CL in dogs. Erythematous, scaly and alopecic macules, patches or plaques were present in eight dogs. Breed predilection was not observed; six of eight dogs were females; and ages ranged from 5 to 14 years. Diffuse monomorphic non-epitheliotropic infiltrates of CD3(+) (eight of eight), CD45(-) (four of eight) or CD45(+/-) (four of eight) and CD45RA(-) (seven of eight) T lymphocytes were present in the superficial and mid-dermis. Further immunophenotyping of five cases revealed TCR-gammadelta(+) T cells (one of five) or TCR-alphabeta(+) (four of five) T cells. TCR-alphabeta(+) populations were either CD8(+) (two of four) or CD4(-)CD8(-) (2/4). Clonality testing found clonal (seven of eight) or pseudoclonal (one of eight) rearrangement of the TCR-gamma locus of the lesional T cells. Prednisone, prednisolone and methylprednisolone acetate were the most commonly administered drugs. The lesions remained stable for long periods up to 6 years. Five dogs were euthanized due to progression of the skin lesions (three of five), peripheral lymphadenopathy of unknown origin (one of five) or high-grade lymphoma (one of five). One dog was lost for follow-up and two dogs are still alive (17 and 9 months after diagnosis). Canine CL is best considered an initially indolent lymphoma, with slow progression and a potential for progression to high-grade lymphoma.

Autoimmunity and risk for Hodgkin's lymphoma by subtype

Hodgkin’s lymphoma (HL) is a lymphoproliferative malignancy of B-cell origin, with an age-adjusted incidence of 2.3–3.1 per 100,000 in the Western world.1 HL is subdivided into classical HL and the rare entity nodular lymphocyte predominant HL (~5% of all HL cases). Based on characteristics of reactive infiltrates and morphology of Reed-Sternberg cells, classical HL is further divided into the following four subtypes: nodular sclerosis (NS), mixed cellularity (MC), lymphocyte-depleted (LD), and lymphocyte-rich (LR).1 Studies have shown that these subtypes have different age-incidence curves, gender ratio, and racial discrepancy.1

Development of a Murine model to dissect the CpG-oligonucleotide-enhancement of the killing of human B Cells by rituximab

As a model to dissect the effects of CpG-oligonucleotides (CpG) on rituximab (RTX)-mediated therapeutic killing of autoimmune or malignant B lymphocytes, nude mice were grafted with Daudi human B cells. These mice were then injected with RTX alone or together with CpG. The human B cell aggregate was measured, and the reactive infiltrate analyzed after selective depletion of murine circulating cells. Macrophages (MØ) were identified in infiltrates, but not polymorphonuclear neutrophils (PMN), as confirmed by the failure of quantitative polymerase chain reaction to detect transcripts for PMN-specific myeloperoxidase in graft extracts. Evidence that MØ predominate over PMN in the anti-B cell RTX-induced immune mechanisms, include the presence of MØ-derived cytokines, and the lack of consequences of depletion of NK cells or B lymphocytes on the CpG-mediated effects on RTX. Interestingly however, removal of circulating PMN reduced the number of MØ attracted by the Daudi B cells. Our interpretation that CpG-induced complement activation is required for PMN to influence MØ was first based on overproduction of C5a in treated mice. This excess was due to the binding of the inhibitor of the alternative pathway of complement to CpG, as demonstrated by the elution of factor H from CpG-affinity-chromatography columns. Thus MØ are recruited to the tissue in the presence of C5a, and exploited locally by RTX.

Use of similar immunoglobulin VH gene segments by MALT lymphomas of the ocular adnexa

Extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue type (MALT lymphomas) develop from acquired reactive infiltrates directed against external or autoantigens. Although some European cases of ocular adnexal MALT lymphoma have been associated with Chlamydia psittaci infections, C. psittaci has not been detected in large studies of US-based cases. To evaluate whether the growth of US-based ocular adnexal MALT lymphomas may be promoted by a similar antigen, we identified and analyzed the expressed immunoglobulin VH genes in 10 cases. Interestingly, the VH genes in two cases used the same VH1 family V1-2 gene segment, and three cases used the same VH4 family V4-34 gene segment. The other five cases all used different gene segments V4-31, V5-51, V3-23, V3-30, and V3-7. All of the VH genes were mutated from germ line, with percent homologies ranging between 96.9 and 89.0%. The distribution of replacement and silent mutations within the VH genes was nonrandom consistent with the maintenance of immunoglobulin function and also strongly suggestive of antigen selection in the six VH genes with highest mutation loads. The CDR3 sequences in two of three VH-34 cases were the same size (15 amino acids) and had similar sizes in the two VH1-2 cases (18 and 16 amino acids). In conclusion, US-based MALT lymphomas of the ocular adnexa preferentially express a limited set of VH gene segments not frequently used by other MALT lymphomas and consistent with some recognizing similar antigens. Analysis of somatic mutations present within the VH genes is also consistent with antigen binding stimulating the growth of these lymphomas.

Infectious agents and lymphoma development: molecular and clinical aspects

This review is focused on the role of infectious agents in the development of some lymphoma entities. Associations involving bacterial infections mostly regard marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT)-type. Some paradigmatic examples of these associations include the Helicobacter pylori-related gastric MALT lymphoma and the more recently reported links between Chlamydophila psittaci and ocular adnexal MALT lymphomas and Borrelia burgdorferi and cutaneous MALT lymphomas. The well-documented association between Epstein-Barr virus infection and related lymphoproliferative disorders are analysed as an example of lymphotropic virus with tumourigenic activity. Molecular, biological and clinical features as well as therapeutic implications of these associations are analysed and future perspectives in this field are discussed.

Pathogenesis of Classical and Lymphocyte-Predominant Hodgkin Lymphoma

Hodgkin and Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (HL) and lymphocytic and histiocytic (L&H) cells in nodular lymphocyte-predominant HL (NLPHL) are derived from germinal-center B cells. HRS cells have, however, largely lost their B cell phenotype and aberrantly express markers and transcriptional regulators of other hematolymphoid cell types. Deregulation of multiple signaling pathways and downstream transcription factors, including receptor tyrosine kinases, nuclear factor-kappa B (NF-kappaB), and Janus kinase/signal transducer and activator of transcription (JAK/STAT), is a further hallmark of HRS cells. These cells harbor genetic lesions that contribute to or cause increases in the activity of transcription factors of the NF-kappaB and STAT families. HRS cells are found within a mixed reactive cellular infiltrate and interact with these nonmalignant cells in a complex fashion that appears to be essential for HRS cell survival and proliferation. Less is known about the pathogenesis of L&H cells in NLPHL, but increases in the activity of receptor tyrosine kinases, NF-kappaB, and JAK/STAT have also been detected.

A new subgroup of immunoglobulin heavy chain variable region genes for the assessment of clonality in feline B-cell lymphomas

In human medicine, PCR-amplification of the complementarity determining region 3 of the immunoglobulin heavy chain genes followed by polyacrylamide gel electrophoresis (PAGE) is an accepted method to assess clonality in B-cell lymphomas and thereby facilitates the differentiation of neoplasias from benign hyperplasias or reactive infiltrates. To generate a basis for the development of a PCR-based assay for the assessment of clonality in feline B-cell lymphomas we analyzed 28 transcripts (cDNA) of the feline immunoglobulin heavy chain variable region genes ( IGHV). Transcripts were generated using techniques for the amplification of unknown sequences (i.e. the SMART™ RACE and the CapFishing™ technique) as well as primers derived from sequences of the NCBI Trace archive of the cat. Analysis of this archive revealed traces similar to the human IGHV-1 and IGHV-3 subgroups of genes. By identification of the subgroup-specific leader sequence within the traces, two subgroup-specific primers for this region were designed and used to amplify the heavy chain variable region genes. Using all amplification techniques, transcripts of both subgroups were created and the subgroups were denominated according to their human counterparts as feline IGHV-1 and feline IGHV-3. By aligning previously described transcripts of the feline IGHV genes to our transcripts we were able to assign these to the IGHV-3 subgroup; therefore, this study provides the first description of the feline IGHV-1 subgroup of genes. On the basis of the IGHV-1 and IGHV-3 transcripts we developed a PCR-based assay. For each of the two subgroups we used one sense primer derived from the first and one sense primer derived from the third framework region each in combination with a mixture of three antisense primers derived from the fourth framework region. With these four sets of primers, the assay was able to detect monoclonality in 7/10 (70%) cats with histologically and immunohistochemically diagnosed B-cell lymphomas. In two of these cases, monoclonal rearrangement of the IGHV genes was only detectable with IGHV-1 subgroup-specific primers. Amplification of feline hyperplastic lymphatic tissue only gave results indicative of polyclonal populations. The use of a PCR-based assay in combination with standard techniques for the diagnosis of feline lymphoma is helpful and the characterization of the additional subgroup of feline variable regions genes puts this assay on a broader basis.

Role of reactive perivascular lymphocytic infiltrate in primary central nervous system lymphoma

Role of reactive perivascular lymphocytic infiltrate in primary central nervous system lymphoma

Relapsed MALT Lymphomas Are Associated with a Restricted VH3-30.3 Immunoglobulin VH Gene Repertoire and Are Targeted by Aberrant Somatic Hypermutation

Mucosa associated lymphoid tissue (MALT) type lymphomas are B-cell neoplasms that develop out of a reactive infiltrate; Sjoegren syndrome, Hashimoto thyroiditis, and Helicobacter pylori gastritis provide the pathogenetic background. Direct antigen stimulation through surface immunoglobulin (Ig) molecules may be playing an important role in the development of MALT lymphomas. In rare cases MALT lymphomas may undergo transformation into extranodal diffuse large B-cell lymphomas (eDLBCL). Previous reports suggested salivary gland MALT lymphomas expressed a restricted Ig VH gene repertoire with over use of VH1-69 gene segments. Because knowledge about the VH gene used by MALT lymphoma of gastric and extragastric origin and by eDLBCL is limited, we sequenced the VH genes from 11 MALT lymphomas [5 of gastric and 6 of extragastric origin (3 salivary gland, 3 thyroid)] and from 10 eDLBCL, all arisen from MALT lymphoma and still exhibiting a low grade component [= so called “transformed MALT lymphoma”: 5 of gastric and 5 of extragastric origin (3 salivary gland and 2 thyroid)]. MALT lymphomas used gene segments of the VH1 (1–69: 2 salivary gland and 1 thyroid), VH3 (3–30.3: 1 thyroid), VH4 (4–34: 1 thyroid, 1 salivary gland and 2 gastric), VH5 (5–51: 2 gastric) and VH6 (6-1: 1 gastric) families. Extranodal DLBCLs used segments derived from VH1 (1–69: 1 gastric and 1 salivary gland), VH2 (2–70: 1 thyroid), VH3 (3–23: 1 gastric; 3–30: 1 gastric; 3–30.3: 1 gastric and 2 salivary glands) and VH4 (4–34: 1 gastric) families as shown in table 1. The VH1-69 gene segment was found in 3 of 6 extragastric MALT lymphomas (2 salivary glands and 1 thyroid), in one gastric and one salivary gland eDLBCL but in no gastric MALT lymphoma. Further, 4 of the 21 lymphomas relapsed, 3 eDLBCL and one MALT lymphoma – and remarkably, all of them used the VH3-30.3 gene segment. Comparing the frequency of somatic hypermutation (SHM) of the immunoglobuline locus and aberrant somatic hypermutation (ASHM) of the four proto-oncogenes PAX-5, PIM-1, Rho/TTF and c-MYC between the relapsed (n=4) and non relapsed lymphomas (n=17) a ~2.9 fold (5.8 vs 2.0 × 10−2/bp, p=0.017) and 2.1 fold (0.067 vs 0.032 × 10−2/bp, p=0.027) higher mutation rate for SHM and ASHM in relapsed lymphomas was observed. Also, the AID mRNA relative expression number was 1.7 fold higher in the group of relapsed lymphomas (4.66 vs 2.71, p=0.049). Performing immunohistochemical analysis for AID a significant positive correlation (p=0.01; correlation coefficient (Spearman rho) = 0.794) was observed when comparing protein expression with mRNA levels. These results are consistent with the model in which only certain B cells displaying specific patterns of VH immunoglobuline molecules binding to an as yet undefined antigen together with a highly aberrant somatic hypermutation process are preferentially selected for malignant transformation and determine the natural course of disease.Table1: VH gene sement used by MALT lymphomas and eDLBCLCaseTypeOriginVH geneRelapseGHM2eDLBCLstomach1–69noGHM3eDLBCLstomach3–23noGHM5eDLBCLstomach3-30-3yesGHM7eDLBCLstomach4–34noGHM8eDLBCLstomach3–30noEHM12eDLBCLthyroid6–1noEHM15eDLBCLsalivary gland3-30-3yesEHM16eDLBCLsalivary gland3-30-3yesEHM18eDLBCLthyroid2–70noEHM19eDLBCLsalivary gland1–69noENM14MALTthyroid3-30-3yesENM21MALTsalivary gland1–69noENM29MALTsalivary gland1–69noENM30MALTsalivary gland4–34noENM33MALTthyroid1–69noENM35MALTthyroid4–34noGNM36MALTstomach5–51noGNM37MALTstomach4–34noGNM38MALTstomach6–1noGNM39MALTstomach5–51noGNM41MALTstomach4–34no

Cutaneous lymphocyte antigen expression in benign and neoplastic cutaneous B‐ and T‐cell lymphoid infiltrates

Cutaneous lymphocyte-associated antigen (CLA) is expressed in resident cutaneous T lymphocytes, high endothelial venules, peripheral monocytes, granulocytes and a small percentage of memory B cells. It has been postulated to be an important factor in homing of lymphocytes to the skin because of its function as a ligand for E-selectin expressed on cutaneous endothelial cells. We investigated the expression of CLA using the HECA-452 antibody on paraffin-embedded, formalin-fixed tissue in a variety of reactive, neoplastic and preneoplastic cutaneous lymphoid infiltrates of T- and B-cell derivation. CLA was expressed at high levels in various types of inflammatory dermatoses with the exception of lupus erythematosus. High levels of CLA expression were seen in epidermotropic T-cell dyscrasias and epidermotropic T-cell lymphomas including mycosis fungoides (MF) and adult T-cell leukemia/lymphoma (ATCLL). A loss of CLA in tumors normally positive for CLA was a feature of disease progression best exemplified by tumor-stage MF and acute ATCLL. There was a lack of CLA expression in those lymphocytic infiltrates manifesting subcutaneous localization including lupus profundus, panniculitis-like T-cell lymphoma and atypical lymphocytic lobular panniculitis. CLA expression was not only observed in primary cutaneous anaplastic large cell lymphoma but also seen in cases of nodal anaplastic large cell lymphoma secondarily involving the skin and was negative in cases of nodal anaplastic large cell lymphoma without any established skin involvement. An oligodot pattern defined a novel reaction pattern in those aggressive systemic dyscrasias with a proclivity to involve the skin. CLA was negative in the majority of B-cell lymphomas. CLA plays a role in the pattern of T-cell lymphocyte migration in the skin and subcutis in both reactive and neoplastic states. An alteration in the expression of this marker, whether it is in the context of the acquisition of expression in a cell that is normally CLA negative or its loss of expression, may define a key event in determining cutaneous and extracutaneous hematopoietic cell distribution.

Evaluation of FoxP3 Expression in Peripheral T-Cell Lymphoma

Peripheral T-cell lymphomas (PTCLs) are biologically heterogeneous and have not been successfully correlated with specific T-cell subsets. We investigated PTCL, not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AILT), and anaplastic large cell lymphoma (ALCL) cases for FoxP3 expression to determine a potential derivation from regulatory T (Treg) cells. One PTCL-NOS case strongly expressed FoxP3 in the neoplastic T cells and showed unusual histomorphologic features with a dense infiltration of the lymph node by immunoblastic T cells and almost no reactive background infiltrate. The patient died shortly after diagnosis, suggesting that biologic properties of Treg cells may have contributed to the rapidly fatal clinical course. All remaining PTCL-NOS and AILT cases showed FoxP3 positivity only in the reactive infiltrate. Among ALCL cases, 4 of 6 ALK+ cases displayed weak and inhomogeneous FoxP3 expression in the tumor cells. FoxP3+ PTCL-NOS presumably derived from bona fide Treg cells occurs but seems rare in the Western population.