Infrequent somatic Fas mutations but no evidence of Bcl10 mutations or t(11;18) in primary cutaneous MALT-type lymphoma

Primary Cutaneous Lymphomas in Children and Adolescents

Primary cutaneous lymphomas are rare in children and mostly represented by mycosis fungoides and CD30(+) lymphoproliferative disorders. Most pediatric cutaneous lymphomas have similar clinical/pathological features as their adult counterparts, particularly the T-cell subtypes. With regard to outcome, adult cutaneous mature T-cell lymphomas have a tendency to progression, while this appears to be relatively infrequent in children. The outcome of cutaneous B-cell lymphomas depends on subtype, with the B-lymphoblastic entity being associated with similar outcomes to precursor B acute lymphoblastic leukemia, while there are insufficient data on other entities. The diagnosis and treatment of these patients require a close collaboration between experienced pediatric pathologists, dermatologists, and oncologists. Prospective collection of longitudinal clinical and biological data from children with these rare lymphomas is needed to better understand their biological and clinical behavior and to ultimately discover the best therapeutic strategies.

Alternative expression pattern of MALT1-A20-NF-κB in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disorder; abnormal T cell immunity plays a critical role in the development of RA. Recently, A20 was identified as a key negative regulator for T cell activation and inflammatory signaling and may be involved in RA pathogenesis. In this study, we analyzed the expression level of A20, NF-κB, and A20 regulatory factor mucosa-associated lymphoid tissue lymphoma translocation gene 1 (MALT1) in patients with RA. Real-time PCR was used to determine the expression level of MALT1, MALT-V1, A20, and NF-κB genes in RA and healthy individuals (HI). Significantly lower A20 expression was found in RA patients compared with those in the healthy group, while NF-κB overexpression could be detected in patients with RA. Moreover, the MALT1 and MALT1-V1 expression level was downregulated in RA patients. A positive correlation between MALT1 and A20 and MALT1-V1 and A20 was found in patients with RA, and a tendency towards a negative correlation was found between MALT1 and NF-κB, MALT1-V1 and NF-κB, and A20 and NF-κB. In conclusion, we first characterized the alternative expression pattern of MALT1, A20, and NF-κB in RA, which may be related to abnormal T cell activation.

Primary cutaneous marginal zone lymphomas with plasmacytic differentiation show frequent IgG4 expression

The expression of IgG4 in malignant B-cell lymphomas has only partially been studied. Recent reports described single cases of marginal zone lymphomas arising in the ocular adnexae that express IgG4. Moreover, a subset of dura-associated marginal zone lymphomas appear to express IgG4 as well. We investigated IgG4 expression in a more systematic manner in a large cohort of marginal zone lymphoma specimens derived from the archive of our institute. Overall, we examined 169 marginal zone lymphomas of various primary sites that displayed a distinct plasmacytic differentiation and light chain restriction, allowing for a detailed investigation of the immunoglobulin heavy chain expression in these tumors by immunohistochemistry. Unexpectedly, primary cutaneous marginal zone lymphomas showed frequent IgG4 expression. Although only 1 out of 120 noncutaneous marginal zone lymphomas, located in the ocular adnexae, expressed IgG4, 19 of 49 (39%) primary cutaneous marginal zone lymphomas showed this feature, constituting the highest expression rate of IgG4 reported to date in any B-cell lymphoma. None of the IgG4-positive cutaneous marginal zone lymphomas with available clinical data showed evidence of a preexisting systemic IgG4-related disease, suggesting a localized immunologic IgG4-driven pathogenetic process at early stages of the disease. IgG4-positive and IgG4-negative primary cutaneous marginal zone lymphomas did not significantly differ in architectural features of the infiltrate or the composition of the reactive T-cell infiltrate as determined by analysis of T-cell content, CD4/CD8 ratio, and content of FOXP3- and PD1-positive T cells. Although the pathogenetic role of IgG4 expression in a significant subset of primary cutaneous marginal zone lymphomas with plasmacytic differentiation remains unclear at present, the demonstration of IgG4 expression in a marginal zone lymphoma involving the skin might be a helpful clue in the routine diagnostic setting, as these tumors will almost invariably be of primary cutaneous origin with an extremely low risk of spread to noncutaneous sites and an excellent prognosis.

Primary cutaneous marginal zone B-cell lymphoma: a molecular and clinicopathological study of cases from Asia, Germany, and the United States

Primary cutaneous marginal zone B-cell lymphoma is considered the cutaneous counterpart of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue. Although its molecular pathogenesis is currently unknown, an etiological link with Borrelia burgdorferi infection has been identified in European, but not in American or Asian cases. To better understand the pathogenesis and the geographical differences of cutaneous marginal zone B-cell lymphoma, 60 cases from the East Asia, Germany, and the United States at their initial presentation were subjected to the following analyses; (1) clinicopathological comparison between the geographical regions, (2) detection of B. burgdorferi DNA, (3) detection of the API2-MALT1 fusion transcript, a gene alteration specific to mucosa-associated lymphoid tissue lymphoma, and (4) inactivation of tumor suppressor genes (death-associated protein kinase (DAPK), p16(INK4a), p14(ARF), MGMT, TIMP3, CDH1, and RARB) by hypermethylation of the CpG islands. Cases from the three geographical regions showed similar clinicopathological features. However, moderate/marked tissue eosinophilia was found in 9/25 Asian cases, but only 1/23 German cases (P=0.011) and 0/12 American cases (P=0.015). All 60 cases were negative for either Borrelia DNA or API2-MALT1 fusion. Tumors from the three regions were highly methylated for DAPK (38-50% of the cases, mean 43%) and p16(INK4a) (42-70%, mean 49%), and the positivities were significantly higher than those of nonneoplastic skin (8%, P=0.0010 and 14%, P=0.0032, respectively). Methylation of these genes had no significant association with progressive features of the tumor. Primary cutaneous marginal zone B-cell lymphomas from the three geographical regions have common clinicopathological features, however, moderate/marked tissue eosinophilia is a feature found almost exclusively in Asian cases. Borrelia infection and API2-MALT1 fusion are not significant in this tumor. Methylation of DAPK and p16(INK4a) genes is a frequent event in this lymphoma at its initial presentation, but may not be associated with tumor progression.

[Cutaneous B-cell lymphoma. Classification and diagnostics]

Primary cutaneous B-cell lymphomas include cutaneous follicle centre lymphoma (PCFCL), cutaneous marginal zone B-cell lymphoma (PCMZL) and cutaneous diffuse large B-cell lymphoma (PCLBCL) "leg type" which are the three main types in the new WHO-EORTC classification for cutaneous lymphomas. PCFCL and PCMZL are indolent lymphomas with an excellent prognosis while PCLBCL shows an aggressive clinical course. All three types must be distinguished from a secondary skin involvement by systemic lymphomas. Since histological and immunohistochemical findings are not decisive, making this distinction requires appropriate staging procedures. In contrast, the pathologist can make an important contribution to the differential diagnosis between neoplastic and reactive cutaneous lymphoproliferations.

Primary cutaneous marginal zone B-cell lymphoma of MALT type in a child

Marginal zone B-cell lymphoma (MZBCL) of mucosa-associated lymphoid tissue type is a peculiar variant of B-cell neoplasm showing distinct clinical and pathologic features. Its occurrence in children or adolescents is extremely uncommon. We describe the case of an 11-year-old boy who developed such a lymphomatous process involving primarily the skin. The tumor was characterized by a maturing plasma cell population that included immunoblasts, heavy-chain but not light-chain restriction suggestive of monoclonality, and a prevalent, focally granulomatous component of histiocytes. As an additional interesting feature, a trisomy 3 was demonstrated by fluorescence in situ hybridization analysis. The clinical, morphological, phenotypic, and genetic characteristics seen in our patient do not differ significantly from those described in primary cutaneous MZBCL occurring in adults.

Cytogenetic and Molecular Analysis of 12 Cases of Primary Cutaneous Marginal Zone Lymphomas

Primary low-grade B-cell lymphomas of the skin are separated into marginal zone and follicle center lymphomas according to the recent World Health Organization-European Organization for Research and Treatment of Cancer classification, with distinct histologic and immunohistochemical profiles. Some cases remain difficult to distinguish. The degree of relationship with their extracutaneous counterparts is currently being investigated on clinical, histologic and molecular grounds. Cytogenetic analysis using fluorescence in situ hybridization was performed on 12 frozen samples of infiltrated skin that had been classified as marginal zone lymphoma (MZL). Chromosomal changes known to be recurrently observed in systemic MZL of the mucosa-associated lymphoid tissue type, and in follicular center lymphoma were analyzed. These included trisomy for chromosomes 3, 7, 12, and 18 as well as t(14;18) IGH/BCL2, t(14;18) IGH/MLT1, and t(11;18) API2/MLT1 translocations. Complementary molecular search of IGH/BCL2 rearrangement using a polymerase chain reaction technique and of API2/MLT1 mRNA expression by reverse transcriptase-polymerase chain reaction were performed. Two cases showed evidence of trisomy 3 at levels varying from 14% to 20% of the analyzed cells. No other chromosomal abnormalities were found with those techniques in the remaining cases. These results demonstrate that known recurrent chromosomal abnormalities rarely occur in primary cutaneous MZLs and suggest the possibility of a variety of initial oncogenic events leading to a common downstream pathway. These data also underline that fluorescence in situ analysis on routine skin punch biopsies represents a reliable tool for the detection of chromosomal changes, but requires consistent dermal infiltration.

Aberrant nuclear BCL10 expression and lack of t(11;18)(q21;q21) in primary cutaneous marginal zone B-cell lymphoma

Inhibition of apoptosis seems to play an important role in the pathogenesis of marginal zone lymphoma. Apoptosis regulator B-cell lymphoma 10 (BCL10) may show aberrant nuclear localization in some aggressive extracutaneous MALT lymphomas, often in association with a MALT1 gene t(11;18)(q21;q21) translocation. The possible occurrence of this association in primary cutaneous marginal zone lymphoma (PCMZL) remains insufficiently explored. The aim of this study was to evaluate BCL10 protein expression pattern and its possible relationship to the presence of t(11;18)(q21;q21) and other MALT1 gene abnormalities in PCMZL and to assess their clinical significance. The study included 42 consecutive PCMZL patients diagnosed on the basis of the World Health Organization/European Organization for the Research and Treatment of Cancer classification criteria. BCL10 expression was immunohistochemically evaluated in all cases, whereas t(11;18)(q21;q21) reverse transcriptase polymerase chain reaction amplification was performed on 21 samples. In addition, the presence of other MALT1 gene translocations was explored in 26 samples by interphase fluorescence in situ hybridization using a MALT1 locus-specific probe. We observed the presence of aberrant nuclear BCL10 expression in a significant number of PCMZL cases (36%, 15/42). This aberrant expression was significantly related to the development of extracutaneous disease. In contrast, neither the t(11;18)(q21;q21) translocation nor other MALT1 gene translocations could be demonstrated. t(11;18)(q21;q21), strongly linked to extracutaneous MALT lymphomas, does not seem to play a role in PCMZL. The participation of other MALT1 gene translocations in PCMZL pathogenesis seems also unlikely.

t(14;18)(q32;q21) involving IGH and MALT1 is uncommon in cutaneous MALT lymphomas and primary cutaneous diffuse large B-cell lymphomas

BACKGROUND

t(14;18)(q32;q21) involving IGH and MALT1 has been demonstrated in cutaneous MALT lymphomas and in one case of primary cutaneous diffuse large B-cell lymphoma (DLBCL). However, the incidence of IGH/MALT1 translocations in these forms of cutaneous lymphoma remains unclear.

METHODS

We performed paraffin section interphase fluorescence in situ hybridization (FISH) analysis using MALT1 and IGH break-apart probes on 16 cutaneous MALT lymphomas and 16 primary cutaneous DLBCL in order to assess the frequency of IGH/MALT1 translocations and to screen for other potential translocations involving the IGH or MALT1 loci.

RESULTS

Translocations involving MALT1 were not detected in any of 16 cutaneous MALT lymphomas or 16 primary cutaneous DLBCL. Of the 12 MALT lymphomas that could be analyzed for an IGH translocation, all were negative. In contrast, four of the 13 cases (31%) of primary cutaneous DLBCL that could be analyzed for translocations involving IGH were positive. Subsequent FISH analysis demonstrated one of these to be an IGH/BCL2 translocation and one to be a CMYC/IGH translocation, while the translocation partners in the remaining two cases are currently unidentified.

CONCLUSIONS

This study demonstrates that translocations involving MALT1, including IGH/MALT1, are uncommon in cutaneous MALT lymphomas and primary cutaneous DLBCL. Other translocations involving IGH also are not involved in the pathogenesis of at least most cutaneous MALT lymphomas. In contrast, primary cutaneous DLBCL may contain one of several IGH translocations in a minority of cases.

New aspects in the biology of cutaneous B-cell lymphomas

Immunologic and molecular genetic studies greatly contributed to a better understanding and interpretation of the distinct clinico-pathologic features of primary cutaneous B-cell lymphomas (CBCL), which are the basis for the consensus WHO-EORTC classification. There is increasingly accumulating evidence that these well defined clinico-pathologic entities of CBCL have specific immunologic and molecular features, which further support their nosologic categorization as well as either interesting similarities with other extranodal B-cell lymphomas or definite peculiarities as compared to nodal B-cell lymphomas of similar histotype (specifically, follicle center lymphoma and diffuse large B-cell lymphoma).

WHO/EORTC classification of cutaneous lymphomas 2005: histological and molecular aspects

The new WHO/EORTC classification for cutaneous lymphomas comprises mature T-cell and natural killer (NK)-cell neoplasms, mature B-cell neoplasms, and immature hematopoietic malignancies. It reflects the unique features of lymphoproliferative diseases of the skin, and at the same time it is as compatible as possible with the concepts underlying the WHO classification for nodal lymphomas and the EORTC classification of cutaneous lymphomas. This article reviews the histological, phenotypical, and molecular genetic features of the various nosological entities included in this new classification. These findings always have to be interpreted in the context of the clinical features and biologic behavior.

AIM

To review the histological, phenotypical and molecular genetic features of the various nosological entities of the new WHO/EORTC classification for cutaneous lymphomas.

METHODS

Extensive review of the literature cited in Medline and own data of the authors.

RESULTS

The WHO/EORTC classification of cutaneous lymphomas comprises mature T-cell and NK-cell neoplasms, mature B-cell neoplasms and immature hematopoietic malignancies. It reflects the unique features of primary cutaneous lymphoproliferative diseases.

CONCLUSION

This classification is as much as possible compatible with the concept of the WHO classification for nodal lymphomas and the EORTC classification of cutaneous lymphomas. The histological, phenotypical and molecular genetic features always have to be interpreted in the context of the clinical features and biologic behavior.

FISH analysis of MALT lymphoma-specific translocations and aneuploidy in primary cutaneous marginal zone lymphoma

Primary cutaneous marginal zone lymphomas (PCMZL) share histological and clinical characteristics with mucosa-associated lymphoid tissue (MALT) lymphomas suggesting a common pathogenesis. A number of recurrent structural and numerical chromosomal aberrations have been described in MALT lymphoma, but their incidence in PCMZL is largely unknown, as is their relation with clinical and pathological data. In this study, the incidence of t(11;18)(q21;q21), t(1;14)(p22;q32), two different t(14;18)(q32;q21), involving either IGH/MALT1 or IGH/BCL2, and numerical aberrations of chromosomes 3, 7, 12 and 18 were analysed in 12 patients with PCMZL, with follow-up of up to 10 years. Nuclei were isolated from paraffin wax sections for dual-colour interphase fluorescence in situ hybridization (FISH) using various probe sets either flanking or spanning the involved genes. T(14;18)(q32;q21), with breakpoints in IGH and MALT1, was found in three cases. All three had partly monocytoid histological appearances and lacked blastic transformation. An additional trisomy of chromosome 3 was detected in one of these cases. Trisomy 18 was present in two lymphomas without monocytoid morphology. No definite correlation was seen with any clinical feature, including Borrelia serology. Neither t(11;18)(q21;q21), nor t(1;14)(p22;q32) or any other translocation involving IGH, BCL10, MALT1, BCL2 and API2, amplification or deletion of chromosomal region 11q21, 18q21, 1p22, and 14q32 was detected. These results indicate that a subgroup of PCMZL with partly monocytoid morphology is genetically related to MZL at other extranodal sites.

Variable frequencies of MALT lymphoma-associated genetic aberrations in MALT lymphomas of different sites

Although several recurrent genetic aberrations are known to occur in MALT lymphoma, no comprehensive study on the most prevalent MALT lymphoma-associated genetic aberrations is available. We therefore screened 252 primary MALT lymphomas for translocations t(11;18)(q21;q21), t(14;18)(q32;q21), and t(1;14)(p22;q32), and trisomies 3 and 18. The above-listed translocations occurred mutually exclusively and were detected overall in 13.5, 10.8, and 1.6% of the cases; trisomy 3 and/or 18 occurred in 42.1%. The frequency at which the translocations occurred varied markedly with the primary site of disease. The t(11;18)(q21;q21) was mainly detected in pulmonary and gastric tumors, whereas the t(14;18)(q32;q21) was most commonly found in lesions of the ocular adnexa/orbit, skin, and salivary glands. Trisomies 3 and 18 each occurred most frequently in intestinal and salivary gland MALT lymphomas. Our results demonstrate that the three translocations and trisomies 3 and 18 occur at markedly variable frequencies in MALT lymphoma of different sites.