Hyperplasia of mantle/marginal zone B cells with clear cytoplasm in peripheral lymph nodes. A clinicopathologic study of 35 cases

Pediatric-type Follicular Lymphoma and Pediatric Nodal Marginal Zone Lymphoma: Recent Clinical, Morphologic, Immunophenotypic, and Genetic Insights

Pediatric-type follicular lymphoma and pediatric nodal marginal zone lymphoma are 2 of the rarest B-cell lymphomas. Although they are both predominantly seen in children, they can manifest in the adult population as well. Our understanding of these lymphomas has advanced rapidly in recent years such that we not only have a firm grasp of the morphologic and immunophenotypic findings, but also have a deeper insight into critical genetic and molecular pathways of these diseases. This review will cover the clinical and pathologic characteristics, treatment, prognosis, and important differential diagnoses of these entities.

Mantle Cell Hyperplasia of Peripheral Lymph Nodes as Initial Manifestation of Sickle Cell Disease

Sickle cell disease (SCD) is a well known hemoglobinopathy with usual manifestations including anemia, hyperbilirubinemia, and vasoocclusive complications. Despite presence of mild splenomegaly in early phase of the disease, lymphadenopathy is not an often finding of SCD. We introduce an undiagnosed case of SCD who presented in third decade of his life with multiple cervical lymphadenopathies and mild splenomegaly persistent for about five years. Histopathologic examination of the resected lymph nodes showed expansion of the mantle cell layers of secondary follicles as well as several monomorphic mantle cell nodules. To rule out possibility of a malignant process involving lymph nodes, an immunohistochemical panel was ordered which was in favor of benign mantle cell hyperplasia. Immunoglobulin gene rearrangement study showed no clonal bands and confirmed benign nature of the process. Respecting mild abnormalities on Complete Blood Count, peripheral blood smear was reviewed revealing some typical sickle red blood cells as well as rare nucleated red blood cells. Solubility test for hemoglobin (HB) S was positive. Hemoglobin electrophoresis confirmed diagnosis of homozygous HbS disease.

Nodal reactive and neoplastic proliferation of monocytoid and marginal zone B cells: an immunoarchitectural and molecular study highlighting the relevance of IRTA1 and T-bet as positive markers

AIMS

Marginal zone B cells (MZCs) and monocytoid B cells (MBCs) appear to be related lymphoid cells that take part in reactive and neoplastic marginal zone proliferations. These lesions are not yet well characterized, and the aim of this study was to find better diagnostic criteria for them.

METHODS AND RESULTS

We analysed 60 nodal lesions with MBC and/or MZC proliferation for their morphological, immunophenotypic, molecular genetic and IG gene rearrangement features. On the basis of the results of the rearrangement assay and immunoglobulin light chain restriction, the lesions were divided into reactive and neoplastic groups. Among the neoplastic lesions, polymorphic and monomorphic subgroups emerged. All reactive lesions had morphological features of the polymorphic subgroup. By immunohistochemistry, IRTA1 and/or T-bet expression was found in all reactive lesions and in 90% of neoplastic lesions.

CONCLUSIONS

IRTA1 and T-bet are positive markers for the identification of MZC/MBC proliferations, and thus for the diagnosis of nodal marginal zone lymphoma (NMZL). Polymorphic and monomorphic subgroups of NMZL could be distinguished. Most morphological and immunophenotypic patterns in reactive and neoplastic nodal expansions of MZCs and MBCs overlapped. Therefore, PCR clonality assay of the immunoglobulin heavy and light chain gene loci is the most reliable method for their differentiation.

Early lesions in lymphoid neoplasia: Conclusions based on the Workshop of the XV. Meeting of the European Association of Hematopathology and the Society of Hematopathology, in Uppsala, Sweden

The increasing use of immunophenotypic and molecular techniques on lymphoid tissue samples without obvious involvement by malignant lymphoma has resulted in the increased detection of "early" lymphoid proliferations, which show some, but not all the criteria necessary for a diagnosis of malignant lymphoma. In most instances, these are incidental findings in asymptomatic individuals, and their biological behaviour is uncertain. In order to better characterize these premalignant conditions and to establish diagnostic criteria, a joint workshop of the European Association for Haematopathology and the Society of Hematopathology was held in Uppsala, Sweden, in September 2010. The panel reviewed and discussed more than 130 submitted cases and reached consensus diagnoses. Cases representing the nodal equivalent of monoclonal B-cell lymphocytosis (MBL) were discussed, as well as the "in situ" counterparts of follicular lymphoma (FL) and mantle cell lymphoma (MCL), topics that also stimulated discussions concerning the best terminology for these lesions. The workshop also addressed the borderland between reactive hyperplasia, and clonal proliferations such as pediatric marginal zone lymphoma and pediatric FL, which may have very limited capacity for progression. Virus-driven lymphoproliferations in the grey zone between reactive lesions and manifest malignant lymphoma were covered. Finally, early manifestations of T-cell lymphoma, both nodal and extranodal, and their mimics were addressed. This workshop report summarizes the most important conclusions concerning diagnostic features, as well as proposals for terminology and classification of early lymphoproliferations and tries to give some practical guidelines for diagnosis and reporting.

Marginal zone lymphomas in children and the young adult population; characterization of genetic aberrations by FISH and RT-PCR

Marginal zone lymphomas present rarely in children and young adults as either primary nodal or extranodal disease and have an excellent prognosis. To date, chromosomal aberrations have not been analyzed in the pediatric and young adult population. We undertook a study to analyze genetic alterations in nodal and extranodal marginal zone lymphomas in children and young adults using fluorescence in situ hybridization (FISH) and RT-PCR. These findings were correlated with clinical features at presentation and immunophenotype. Forty-one cases were identified meeting these criteria. The age range was 1.5-29 years old with 49% of the cases <18 years of age. 73% of the marginal zone lymphoma cases showed evidence of light chain restriction by immunohistochemistry or flow cytometry. CD43 was coexpressed in 83%. 85% of the marginal zone lymphoma cases tested showed evidence of immunoglobulin heavy chain gene rearrangement. Fifty-nine percent of the cases were nodal marginal zone lymphomas with a median age at presentation of 16 years and an M/F ratio of 7:1. Twenty-one percent of the nodal marginal zone lymphoma cases contained genetic aberrations. Seventeen percent contained trisomy 18 with one case containing an additional trisomy 3. A translocation of the immunoglobulin heavy chain gene to an unknown partner gene was present in one case. Forty-one percent of the cases were extranodal marginal zone lymphomas with a median age of 24 years and a M/F ratio of 1.4:1. Eighteen percent of the extranodal marginal zone lymphoma cases contained genetic aberrations. The t(14;18) involving the IGH and MALT1 genes was present in one case, tetraploidy was present in one case, and another case contained trisomy 3. Overall the incidence of genetic aberrations in marginal zone lymphomas in the pediatric and young adult population is low, but the aberrations seen are similar to those seen in the adult population.

"Follicular variant" of hyaline-vascular type of Castleman's disease: histopathological and immunohistochemical study of 11 cases

Occasionally, the hyaline-vascular type of Castleman's disease (HVCD) contains numerous lymphoid follicles which usually occupy more than 50% of the lesion. Such lesions are called the follicular variant (FV) of HVCD. To clarify the histological and immunohistochemical findings of lymphoid follicles in the FV of HVCD, we examined 11 such cases. Histologically, five types of lymphoid follicles were delineated. Lymphoid follicles ; (i) with normal germinal centers (GCs) ; (ii) showing follicular lysis ; (iii) with progressive transformation of GC (PTGC) ; (iv) where the large nodule of mantle zone lymphocytes contained multiple small atrophic GCs (multiple GC pattern) ; and (v) where the large, often irregularly shaped nodules of mantle cells radically penetrated small vessels with inconspicuous GCs. These nodules somewhat resembled primary lymphoid follicles (primary follicular pattern). The majority of lymphoid follicles in all 11 cases were of the primary follicular pattern and/or multiple GC pattern. However, three lesions also contained normal germinal GC, while two contained normal GC, follicular lysis and PTGC and one other contained normal GC and PTGC. Moreover, in 3 cases of primary follicular pattern, the majority of the lymphoid follicles were surrounded by a pale cuff of mantle cells. Because of the presence of numerous lymphoid follicles, the FV of HVCD should be sometimes differentiated from Hodgkin lymphoma and low-grade B-cell lymphomas showing follicular growth pattern. Recognition of the histological and immunohistochemical findings of the FV of HVCD is needed to avoid overdiagnosis.

Focal lymphoid hyperplasia of the terminal ileum presenting mantle zone hyperplasia with clear cytoplasm. A report of three cases

We report three unusual cases of focal lymphoid hyperplasia of the ileocecal valve. The gross specimens showed thickening of the ileocecal valve. Low power magnification showed a dense lymphoid infiltrate in the mucosa and submucosa. This condition was characterized by reactive lymphoid follicles with large reactive germinal centers surrounded by a pale cuff of mantle zone lymphocytes presenting a marginal zone distribution pattern. These cells had intermediate- to- medium-sized round or slightly indented nuclei and a broad rim of clear cytoplasm. However, immunohistochemical study demonstrated that both the mantle zone lymphocytes and the pale cuff of the lymphoid cells were CD20+, sIgM+, sIgD+, CD5-, CD10-, CD23-, CD43-, Bcl-2+, Bcl-6-, CyclinD1-. The polytypic nature of these cells was demonstrated by immunohistochemistry and polymerase chain reaction. This unusual mantle cell hyperplasia with clear cytoplasm associated with focal lymphoid hyperplasia in middle-aged and elderly patients should be differentiated from the extranodal marginal zone B-cell lymphoma of mucosa associated lymphoid tissue type or mantle cell lymphoma showing a marginal zone distribution pattern. To avoid overdiagnosis and overtreatment, it is suggested that immunophenotypic and genotypic studies might be required, and careful attention should be paid to the morphologic examination.

Reactive lymphoid follicular hyperplasia mimicking a peripheral nerve tumor

BACKGROUND

Reactive lymphoid follicular hyperplasia is a benign proliferation of lymphoid follicles, which can develop wherever lymphoid tissue is present. We present the unique case of an RLFH that involved the radial nerve and presented as a peripheral nerve tumor.

CASE DESCRIPTION

A 62-year-old woman came to our attention because of the evidence of a mass in her right arm, associated with numbness in the lateral aspect of her right arm and forearm. Magnetic resonance findings revealed a contrast-enhancing, spindle-shaped tumor, suggestive of a schwannoma or neurofibroma, along the course of the radial nerve. The intraoperative appearance was that of an infiltrating tissue around a lateral branch of the nerve, which could be resected en bloc. Pathologic examination documented hyperplastic lymphoid tissue surrounding the nerve, and immunostaining confirmed the diagnosis of benign reactive follicular hyperplasia. Systemic infections and autoimmune disorders were excluded by screening examinations. The patient remains free of recurrence 24 months postoperatively.

CONCLUSION

To our knowledge this is the first description of RLFH affecting a peripheral nerve and mimicking a neoplasm. This rare and benign condition should be considered in the differential diagnosis of peripheral nerve tumors.

"In situ-like" mantle cell lymphoma: a report of two cases

Mantle cell lymphoma (MCL) is a B cell neoplasm that most often shows a diffuse growth pattern. Two cases of MCL are reported here, both with a previous diagnosis of lymphoid hyperplasia. Morphologically, germinal centres are hyperplasic with a normal or discretely enlarged mantle zone, where foci of irregularly shaped small lymphocytes are seen. These are positive for CD20, CD5 and cyclin D1, confirming a diagnosis of in situ-like MCL. This type differs from the mantle zone pattern in that the neoplastic mantle zone is very thin and there is very little or no spread of tumour cells into interfollicular areas. To the best of our knowledge, this is the first report on such a pattern of MCL, which is important to recognise, as it can be confused with lymphoid hyperplasia.

Lymphoid variant of hyaline vascular Castleman's disease containing numerous mantle zone lymphocytes with clear cytoplasm

We report two unusual cases of hyaline vascular type Castleman's disease showing a pale clear cuff of mantle zone lymphocytes presenting a marginal zone distribution pattern. These cells had medium-sized round or slightly indented nuclei and a moderate amount of clear cytoplasm. The histopathologic findings in our cases were similar to those of nodal marginal zone B-cell lymphoma. However, immunohistochemistry demonstrated that both the mantle zone lymphocytes and the pale cuff of the lymphoid cells were CD20+, CD79a+, sIgM+, sIgD+, CD5-, CD10-, CD43-, CD45RO-, Bcl-2+, Bcl-6- and cyclin D1-. The polytypic nature of these cells was demonstrated by immunohistochemistry and polymerase chain reaction. Reactive lymph node lesions only rarely show mantle cell hyperplasia with clear cytoplasm. This unusual mantle cell hyperplasia with clear cytoplasm associated with a hyaline vascular type of Castleman's disease should be differentiated from nodal marginal zone B-cell lymphoma, mantle cell lymphoma and follicular lymphoma. To avoid overdiagnosis and overtreatment, it is suggested that immunophenotypic and genotypic studies might be required, and furthermore careful attention should be paid to the morphologic examination.

Massive hyperplasia of marginal zone B-cells with clear cytoplasm in the lymph node: a case report

An enlarged axillary lymph node from a 63-year-old woman showed proliferating marginal zone B-cells arranged in a vague nodular pattern or in band-forming aggregates throughout the cortex. Marginal zone B-cells, which also infiltrated the adjacent fatty tissue, had round or slightly indented nuclei of medium size and a moderate amount of clear cytoplasm. Immunohistochemically, these cells were CD20+, CD79a+, Bcl-2+, sIgD-, CD5-, CD10-, CD21-, CD23-, CD45RO-, Bcl-6-, and cyclin D-. A portion of the cells were sIgM- and CD43-positive. The polytypic nature of these cells was demonstrated by immunohistochemistry and polymerase chain reaction. Systemic bacterial infection appears to be the cause of marginal zone B-cell hyperplasia. This unusual marginal zone B-cell hyperplasia should be differentiated from low-grade B cell lymphomas, and particularly from nodal marginal zone B-cell lymphomas.

BCL-2 is consistently expressed in hyperplastic marginal zones of the spleen, abdominal lymph nodes, and ileal lymphoid tissue

BCL-2 is an antiapoptotic protein overexpressed in follicular lymphomas, principally as a result of the t(14;18)(q32;q21), and useful in distinguishing follicular lymphoma (usually BCL-2 positive) from follicular hyperplasia (BCL-2 negative). BCL-2 is also overexpressed in other lymphoma types without the t(14;18), including marginal zone B-cell lymphoma, because of other, poorly understood mechanisms. It has been suggested that BCL-2 immunoreactivity can distinguish between malignant (BCL-2 positive) and reactive (BCL-2 negative) marginal zone B cells. In this study, we evaluated 26 spleen, 10 abdominal lymph node, and 3 ileum specimens with marginal zone B-cell hyperplasia for BCL-2 expression immunohistochemically. We also analyzed these cases using polymerase chain reaction methods to evaluate for the presence of clonal rearrangements of the immunoglobulin heavy chain gene (IgH) using consensus V FRIII and J region primers, and the t(14;18) involving both the major breakpoint and the minor cluster regions of the bcl-2 gene. All (100%) cases of splenic, abdominal lymph node, and ileal marginal zone hyperplasia displayed strong BCL-2 reactivity in the marginal zone B cells. In all cases analyzed, IgH polymerase chain reaction demonstrated a polyclonal pattern, and bcl-2/JH DNA fusion sequences were not detected. Our results indicate that BCL-2 is consistently expressed by reactive marginal zone B cells of the spleen, abdominal lymph nodes, and ileal lymphoid tissue and should not be used as a criterion for discriminating between benign and malignant marginal zone B-cell proliferations involving these sites.

Marginal zone B-cell lymphoma in children and young adults

We describe the clinicopathologic findings of 48 cases of marginal zone B-cell lymphoma (MZL) in children and young adults, a disease that has been recognized previously only rarely in this age group. Patients ranged in age from 2 to 29 years, with pediatric patients (< or =18 years) comprising 52% of the cases. As in adults, both primary nodal (N) and extranodal (E) MZL were observed. However, primary NMZL comprised the majority of the cases (67%) and demonstrated distinctive clinical and histologic features. NMZL occurred most commonly in young males (median 16 years, male/female ratio 5.4:1), with no underlying disease, presenting as localized adenopathy (90% stage I), with excellent prognosis and low rate of recurrence. In contrast, EMZL were much less common, and patients were older (median 24.5 years), with only a slight male predominance (male/female ratio 1.2:1). Most patients had localized disease (73% stage I) with excellent prognosis and infrequent recurrences. In addition, an association with autoimmune disease was observed in 19% of the EMZL. Both primary NMZL and EMZL in young patients shared similar morphologic and immunophenotypic findings to those described in adults and were monoclonal B-cell proliferations with monoclonality demonstrated in 94% of the cases. A common morphologic feature in NMZL was disruption of residual follicles resembling progressive transformation of germinal centers (PTGC), observed in 66% of the cases. Although the precise relationship of primary NMZL and the PTGC-like changes is unclear, it is possible that NMZL arises in a background of PTGC, as florid PTGC often occurs in young males. We conclude that EMZL in children and young adults are similar to EMZL of mucosa-associated lymphoma tissue occurring in older patients. However, pediatric NMZL appear to have distinctive clinical and histologic features.