Anaplastic large cell lymphoma: a distinct molecular pathologic entity: a reappraisal with special reference to p80(NPM/ALK) expression

ALK-negative CNS anaplastic large cell lymphoma: case report and review of literature

BACKGROUND

Central nervous system (CNS) lymphomas frequently pose a diagnostic challenge to physicians. CNS anaplastic large cell lymphoma (ALCL) is a rare condition. A majority (80%) of ALCLs harbour anaplastic lymphoma kinase 1 (ALK-1) mutation with only a minority testing negative for this mutation.

METHODS

Here we report a rare case of ALK-negative CNS ALCL with dural involvement. We conducted a literature search using PubMed for published studies in English on cases of patients with ALCL of the brain. The keywords used were 'anaplastic large cell lymphoma', 'ALK' and 'primary central nervous system lymphoma'.

RESULTS

A 63-year-old man presents with waxing and waning cranial nerve and spinal cord symptoms. MRI revealed multiple intracranial and intra-spinal lesions that were highly steroid responsive. A wide range of serum and CSF tests were non-diagnostic during three months of workup before a lesion appeared in the cervical spine that required decompression and allowed us to obtain a tissue sample. Final pathology revealed ALK-negative ALCL. There are only 24 reported adult cases to date of CNS ALCL in the English literature. To our knowledge, this is the first case of ALK-negative ALCL with primarily CNS and meningeal involvement.

CONCLUSIONS

ALK-negative ALCL with CNS involvement is extremely rare, which frequently results in delayed diagnosis (average 40.5 days). The diagnostic challenge posed by this case highlights the importance of a team approach to workup and diligent patient follow-up for such a rare disease.

Mutations in ALK signaling pathways conferring resistance to ALK inhibitor treatment lead to collateral vulnerabilities in neuroblastoma cells

BACKGROUND

Development of resistance to targeted therapies has tempered initial optimism that precision oncology would improve poor outcomes for cancer patients. Resistance mechanisms, however, can also confer new resistance-specific vulnerabilities, termed collateral sensitivities. Here we investigated anaplastic lymphoma kinase (ALK) inhibitor resistance in neuroblastoma, a childhood cancer frequently affected by activating ALK alterations.

METHODS

Genome-wide forward genetic CRISPR-Cas9 based screens were performed to identify genes associated with ALK inhibitor resistance in neuroblastoma cell lines. Furthermore, the neuroblastoma cell line NBLW-R was rendered resistant by continuous exposure to ALK inhibitors. Genes identified to be associated with ALK inhibitor resistance were further investigated by generating suitable cell line models. In addition, tumor and liquid biopsy samples of four patients with ALK-mutated neuroblastomas before ALK inhibitor treatment and during tumor progression under treatment were genomically profiled.

RESULTS

Both genome-wide CRISPR-Cas9-based screens and preclinical spontaneous ALKi resistance models identified NF1 loss and activating NRASQ61K mutations to confer resistance to chemically diverse ALKi. Moreover, human neuroblastomas recurrently developed de novo loss of NF1 and activating RAS mutations after ALKi treatment, leading to therapy resistance. Pathway-specific perturbations confirmed that NF1 loss and activating RAS mutations lead to RAS-MAPK signaling even in the presence of ALKi. Intriguingly, NF1 loss rendered neuroblastoma cells hypersensitive to MEK inhibition.

CONCLUSIONS

Our results provide a clinically relevant mechanistic model of ALKi resistance in neuroblastoma and highlight new clinically actionable collateral sensitivities in resistant cells.

The Grey Zones of Classic Hodgkin Lymphoma

Simple Summary

Classic Hodgkin lymphoma (CHL) is a well-defined lymphoid neoplasm with a minority of characteristic neoplastic cells of B cell origin, namely Hodgkin and Reed–Sternberg cells immersed in a rich reactive inflammatory infiltrate in the background. Although CHL has always been set apart from non-Hodgkin lymphomas, cases with morphological and phenotypic features intermediate between CHL and other lymphomas have been described. Whereas some of these lymphomas only represent morphological mimics, others exhibit mutational and gene expression profiles which overlap with CHL, indicating that these cases, frequently termed grey zone lymphomas, reside on the biological boundary between CHL and large B-cell lymphomas. In the present review, we aim to describe the current knowledge of these rare lymphomas, address diagnostic issues and summarize today’s concepts on the classification of grey zone lymphomas and related tumors.

Abstract

Classic Hodgkin lymphoma (CHL) is a well-defined neoplasm characterized by the presence of a minority of pathognomonic Hodgkin and Reed–Sternberg (HRS) cells in a reactive inflammatory background. Although genotypically of B cell origin, HRS cells exhibit a downregulated B cell program and therefore are set apart from other B cell lymphomas in the current WHO classification. However, cases with morphological and phenotypic features overlapping with CHL have been recognized, and the category of B cell lymphoma—unclassifiable—with features intermediate between diffuse large B cell lymphoma (DLBCL) and CHL, also termed grey zone lymphoma, was first introduced into the WHO classification in 2008 as provisional entity. These cases, as well as others raising a differential diagnosis of CHL can present diagnostic problems, as well as therapeutic challenges. Whereas some of these lymphomas only represent biologically unrelated morphological mimics, others, especially mediastinal grey zone lymphoma, exhibit genetic and gene expression profiles which overlap with CHL, indicating a true biological relationship. In this review, we address areas of diagnostic difficulties between CHL and other lymphoma subtypes, discuss the biological basis of true grey zone lymphoma based on recent molecular studies and delineate current concepts for the classification of these rare tumors.

CD30 Differential Staining is Useful in Classifying Lymphomas Intermediate between Hodgkin's Disease and Anaplastic Large Cell (Ki1) Lymphoma

AIMS AND BACKGROUND

The authors analyzed the BerH2 reactivity patterns of the tumor cells in 23 Hodgkin's lymphomas (HD), in 13 CD30+ anaplastic large cell (Ki1) lymphomas (ALCL), in two HD with transition to secondary CD30+ ALCL, and in six additional lymphomas intermediate between HD and ALCL.

METHODS

Paraffin blocks of formalin-fixed biopsies were immunostained. Immunostaining was modified by pronase digestion and by microwave assistance.

RESULTS

Hodgkin-Reed-Sternberg (HRS) cells of all 23 Hodgkin's lymphomas were reactive for BerH2, but the reactivity patterns differed: after pronase digestion, HRS cells of 17/23 Hodgkin's lymphomas showed exclusively or at least predominantly cytoplasmic BerH2 reactivity, whereas only four Hodgkin's lymphomas presented with prominent membrane-bound positivity. Microwave processing in 16/23 Hodgkin's lymphomas induced membrane-bound BerH2 positivity in the HRS cells; a minority of five cases retained the distinct cytoplasmic pattern. In contrast, 10/13 ALCLs were characterized by membranous reactions, independent of whether pronase or microwave pretreatment had been applied. The CD30+ ALCLs secondary to HD also showed a tendency towards membranous positivity more than did the antecedent Hodgkin's lymphomas. In the HD/ALCL borderline group, 3/6 cases revealed cytoplasmic BerH2 patterns after pronase digestion and thus were more closely related to HD, whereas 2/6 cases reacted with membranous positivity as did the genuine ALCLs of our series.

CONCLUSIONS

We conclude from these findings that the above modifications in CD30 immunostaining can be helpful in the characterization of lymphomas that constitute a continuous histomorphological as well as phenotypical spectrum between HD and ALCL.

Anaplastic variant of diffuse large B-cell lymphoma with hallmark cell appearance: Two cases highlighting a broad diversity in the diagnostics

The anaplastic variant of diffuse large B-cell lymphoma (A-DLBCL) is morphologically defined but remains an enigmatic disease in its clinicopathologic distinctiveness. Here, we report two cases involving Japanese women aged 59 years, both with A-DLBCL with the hallmark cell appearance and both indistinguishable from common and giant cell-rich patterns, respectively, of anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma. Case 1 was immunohistochemically positive for CD20, CD79a and OCT-2 but not for the other pan-B-cell markers, CD30 and ALK. Case 2 showed CD20 and CD30 positivity for 50% and 20% of tumor cells in addition to strong expression of p53 and MYC. Both were positive for fascin without Epstein-Barr virus association. Our cases provide additional support for the earlier reports that A-DLBCL exhibits clinicopathologic features distinct from ordinal diffuse large B-cell lymphoma (DLBCL), and documented its broader morphologic diversity than previously recognized. They also shed light on the unique feature of absent expression of pan-B-cell markers except for CD20 and CD79a, suggesting that A-DLBCL may biologically mimic a gray zone or intermediate lymphoma between DLBCL and classic Hodgkin lymphoma.

Anaplastic large T-cell lymphoma in three black-tailed prairie dogs (Cynomys ludovicianus)

Anaplastic large T-cell lymphoma (ALTCL) is rarely reported in domestic animals. Accordingly, the histopathological and immunohistochemical characteristics of ALTCL have not been well established in prairie dogs. The present report documents three cases in which prairie dogs were diagnosed with ALTCL arising in the subcutaneous tissue, oral mucosa or the mesenteric lymph nodes. Of the three cases, one was available for necropsy and the others were biopsy cases. Microscopically, moderate to large, pleomorphic neoplastic lymphocytes with ovoid to polygonal, bizarre-shaped nuclei, abundant cytoplasm and eosinophilic granules were seen in all cases. Immunohistochemical staining revealed membranous or cytoplasmic CD3 expression of the neoplastic lymphocytes. The neoplastic cells often had granzyme B-positive cytoplasmic granules. One of the prairie dogs with nodal ALTCL suffered systemic dissemination of the tumor and died suddenly. In the two biopsy cases, one animal died on the day of the biopsy examination and the other died six weeks after chemotherapy. ALTCL in prairie dogs displays a cytotoxic T cell phenotype and presumably carries a poor prognosis regardless of the anatomical type.

Anaplastic large cell lymphoma: pathology, genetics, and clinical aspects

Anaplastic large cell lymphoma (ALCL) was first described in 1985 as a large-cell neoplasm with anaplastic morphology immunostained by the Ki-1 antibody, which recognizes CD30. In 1994, the nucleophosmin (NPM)-anaplastic lymphoma kinase (ALK) fusion receptor tyrosine kinase was identified in a subset of patients, leading to subdivision of this disease into ALK-positive and -negative ALCL in the present World Health Organization classification. Due to variations in morphology and immunophenotype, which may sometimes be atypical for lymphoma, many differential diagnoses should be considered, including solid cancers, lymphomas, and reactive processes. CD30 and ALK are key molecules involved in the pathogenesis, diagnosis, and treatment of ALCL. In addition, signal transducer and activator of transcription 3 (STAT3)-mediated mechanisms are relevant in both types of ALCL, and fusion/mutated receptor tyrosine kinases other than ALK have been reported in ALK-negative ALCL. ALK-positive ALCL has a better prognosis than ALK-negative ALCL or other peripheral T-cell lymphomas. Patients with ALK-positive ALCL are usually treated with anthracycline-based regimens, such as combination cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) or CHOEP (CHOP plus etoposide), which provide a favorable prognosis, except in patients with multiple International Prognostic Index factors. For targeted therapies, an anti-CD30 monoclonal antibody linked to a synthetic antimitotic agent (brentuximab vedotin) and ALK inhibitors (crizotinib, alectinib, and ceritinib) are being used in clinical settings.

Anaplastic large cell lymphomas: ALK positive, ALK negative, and primary cutaneous

Anaplastic large cell lymphomas (ALCLs) comprise a group of CD30-positive non-Hodgkin lymphomas that generally are of T-cell origin and share common morphologic and phenotypic characteristics. The World Health Organization recognizes 3 entities: primary cutaneous ALCL (pcALCL), anaplastic lymphoma kinase (ALK)-positive ALCL, and, provisionally, ALK-negative ALCL. Despite overlapping pathologic features, these tumors differ in clinical behavior and genetics. pcALCL presents in the skin and, while it may involve locoregional lymph nodes, rarely disseminates. Outcomes typically are excellent. ALK-positive ALCL and ALK-negative ALCL are systemic diseases. ALK-positive ALCLs consistently have chromosomal rearrangements involving the ALK gene with varied gene partners, and generally have a favorable prognosis. ALK-negative ALCLs lack ALK rearrangements and their genetic and clinical features are more variable. A subset of ALK-negative ALCLs has rearrangements in or near the DUSP22 gene and has a favorable prognosis similar to that of ALK-positive ALCL. DUSP22 rearrangements also are seen in a subset of pcALCLs. In this review, we discuss the clinical, morphologic, phenotypic, genetic, and biological features of ALCLs.

Endoscopic and clinical analysis of primary T-cell lymphoma of the gastrointestinal tract according to pathological subtype

BACKGROUND AND AIM

Little is known about the clinicopathological characteristics of primary gastrointestinal T-cell lymphomas (PGITL). This study evaluated the clinical and endoscopic features of the pathological subtypes of PGITL.

METHODS

Forty-two lesions in 36 patients with PGITL were assessed, including 15 enteropathy-associated T-cell lymphomas (EATL), 13 peripheral T-cell lymphomas (PTCL), 10 NK/T-cell lymphomas (NK/TL), and four anaplastic large cell lymphomas (ALCL).

RESULTS

PTCL occurred more frequently in the stomach and duodenum and NK/TL more frequently in the small and large intestines (P = 0.009). The endoscopic features of the four subtypes were similar (P = 0.124). Fifteen of 41 lesions (36.6%) were Epstein-Barr virus (EBV) positive, with NK/TL more likely to be EBV positive than the other types (P < 0.001). First endoscopy and first computed tomography (CT) scan indicated that 65.4% and 51.4% of the lesions, respectively, were malignant, and that 43.2% and 42.3%, respectively, were GI lymphomas. The two modalities together correctly diagnosed about half of the lesions before biopsy. Intestinal perforation was associated with small bowel location (P < 0.001) and infiltrative type (P = 0.009), and was more common in NK/TL than in the other subtypes (P = 0.015). Multivariate analysis showed that higher international prognosis index (P = 0.008) and the presence of complications (P = 0.006) were associated with poor prognosis. Survival was poorer in patients with small bowel lesions than with lesions at other locations (P = 0.048).

CONCLUSIONS

The four main pathological types of PGITL differed in clinical characteristics. As PGITL was often not diagnosed by initial endoscopic or radiological examination, a high index of suspicion is necessary to ensure its early diagnosis.

ALK as a paradigm of oncogenic promiscuity: different mechanisms of activation and different fusion partners drive tumors of different lineages

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase protein implicated in a variety of hematological malignancies and solid tumors. Since the identification of the ALK gene in 1994 as the target of the t(2;5) chromosomal translocation in anaplastic large cell lymphoma, ALK has been proven a remarkably promiscuous oncogene. ALK contributes to the development of a notable assortment of tumor types from different lineages, including hematolymphoid, mesenchymal, epithelial and neural tumors, through a variety of genetic mechanisms: gene fusions, activating point mutations, and gene amplification. Recent developments led to significant diagnostic and therapeutic advances, including efficient diagnostic tests and ALK-targeting agents readily available in the clinical setting. This review addresses some therapeutic considerations of ALK-targeted agents and the biologic implications of ALK oncogenic promiscuity, but the main points discussed are: 1) the variety of mechanisms that result in activation of the ALK oncogene, with emphasis on the promiscuous partnerships demonstrated in chromosomal rearrangements; 2) the diversity of tumor types of different lineages in which ALK has been implicated as a pathogenic driver; and 3) the different diagnostic tests available to identify ALK-driven tumors, and their respective indications.

Role of mucins in the skin during benign and malignant conditions

Skin-related diseases comprise a major health challenge to the practicing physician, and constitute a significant psychological, social and financial burden to the society. Further, skin cancer, especially non-melanoma skin cancer is currently the leading type of malignancy in the Western world. Given the huge burden of skin diseases, there is growing emphasis on understanding their pathophysiology, and towards their early detection. Mucins are high-molecular weight O- and N-linked glycoproteins that have emerged in recent years as important molecules in maintaining health and in promoting or protecting against inflammation and cancer. They have also begun to emerge as highly specific diagnostic and prognostic markers and novel therapeutic targets in several malignant disorders. However, their role in cutaneous pathologies has remained largely obscured. The present review provides the expression patterns and proposed role of mucins in the healthy skin and various benign and malignant skin diseases. The review has immense clinical significance as the availability of highly specific reagents including monoclonal antibodies against mucins makes them extremely attractive targets for specific diagnosis and/or immunotherapy of benign and malignant cutaneous diseases.

Development of anaplastic lymphoma kinase (ALK) small-molecule inhibitors for cancer therapy

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase (RTK) involved in the genesis of several human cancers; indeed, ALK was initially identified in constitutively activated and oncogenic fusion forms--the most common being nucleophosmin (NPM)-ALK--in a non-Hodgkin's lymphoma (NHL) known as anaplastic large-cell lymphoma (ALCL) and subsequent studies identified ALK fusions in the human sarcomas called inflammatory myofibroblastic tumors (IMTs). In addition, two recent reports have suggested that the ALK fusion, TPM4-ALK, may be involved in the genesis of a subset of esophageal squamous cell carcinomas. While the cause-effect relationship between ALK fusions and malignancies such as ALCL and IMT is very well established, more circumstantial links implicate the involvement of the full-length, normal ALK receptor in the genesis of additional malignancies including glioblastoma, neuroblastoma, breast cancer, and others; in these instances, ALK is believed to foster tumorigenesis following activation by autocrine and/or paracrine growth loops involving the reported ALK ligands, pleiotrophin (PTN) and midkine (MK). There are no currently available ALK small-molecule inhibitors approved for clinical cancer therapy; however, recognition of the variety of malignancies in which ALK may play a causative role has recently begun to prompt developmental efforts in this area. This review provides a succinct summary of normal ALK biology, the confirmed and putative roles of ALK fusions and the full-length ALK receptor in the development of human cancers, and efforts to target ALK using small-molecule kinase inhibitors.

Human antibody RNase fusion protein targeting CD30+ lymphomas

Targeted RNases (TRs) are immunoenzymes with ribonucleases as cytotoxic effector domains, which are less immunogenic as plant or bacterial toxin components of classical immunotoxins. In this study, we show the generation and production of the first entirely human TR (huTR) directed against CD30+ lymphomas. The scFv-Fc-RNase construct was produced in human embryonic kidney (HEK) 293T cells, yielding up to 4 mg/L soluble protein after purification by protein A affinity chromatography. Size exclusion chromatography revealed a homodimer of the predicted molecular mass. Surface plasmon resonance analysis revealed an affinity to CD30 of KD of less than 1 nM for both the scFv-Fc and the scFv-Fc-RNase proteins. Internalization of the scFv-Fc-RNase protein by CD30+ Karpas-299 cells was demonstrated by confocal microscopy. Proliferation of the CD30+ lymphoma cell line Karpas-299 was strongly inhibited by CD30-specific huTR protein (IC50 = 3.3 nM). The huTR is a promising candidate for the immunotherapy of CD30+ lymphomas because of its expected low immunogenicity, good production yields, and potent effector function upon target cell binding and internalization. Its modular design is set to target other internalizing tumor antigens using different antibody domains.

Cytotoxic molecule expression is predictive of prognosis in Hodgkin's-like anaplastic large cell lymphoma

AIMS

The Revised European American Lymphoma classification uses the term Hodgkin's-like anaplastic large cell lymphoma (HD-like ALCL) for borderline cases with features of both anaplastic large cell lymphoma (ALCL) and classical Hodgkin's lymphoma (HL). The aim of this study was to clarify the association between cytotoxic molecule (CM) expression and clinical outcome in HD-like ALCL.

METHODS AND RESULTS

Subjects were 59 patients with HD-like ALCL, defined by nodal presentation without mediastinal bulky lesions, T- or null-cell phenotype, CD30+ anaplastic lymphoma kinase (ALK)- phenotype and by confluent sheets or nodules of large cells mimicking classic Hodgkin and Reed-Sternberg cells. We evaluated the presenting features and prognosis of subjects on categorization into two defined groups, namely CM (TIA1 and/or granzyme B)-positive (n = 21) and CM-negative (n = 38). The series consisted of 18 women and 41 men ranging from 16 to 88 years of age (median 59 years). The CM+ group had poorer disease-specific survival than the CM- group (P = 0.02) despite the absence of differences in other clinical characteristics. Multivariate analysis confirmed that CM expression was an independent prognostic factor, in contrast to phenotypic categorization (T-cell vs. null-cell group), which had no prognostic impact on disease-specific survival.

CONCLUSION

CM expression is predictive of prognosis in HD-like ALCL.

Highly aggressive ALK-positive anaplastic large cell lymphoma with a leukemic phase and multi-organ involvement: a report of three cases and a review of the literature

Anaplastic large cell lymphoma (ALCL) is an aggressive neoplasm of T- or null cell phenotype and is recognized as a distinct clinicopathologic subtype of non-Hodgkin lymphoma (NHL) in the revised World Health Organization (WHO) classification of hematopoietic neoplasms. It is rarely associated with leukemic phase. Most cases with leukemic involvement are the small cell variant of ALCL. These cases often lack the pleomorphism seen in the common variant of ALCL and may be misdiagnosed. We report a series of three patients who presented with leukemic phase ALCL. The patients included an 11-year-old boy, a 29-year-old man, and a 59-year-old woman. The clinical and pathologic features of these cases are reviewed. The patients in our case series with leukemic phase ALCL exhibited rare clinical features. The patients presented with massive extranodal disease involving cerebrospinal fluid (CSF), liver, spleen, lungs, and bone marrow. CSF involvement was documented morphologically as well as by flow cytometry in two patients. Two of the patients had small cell variant and the third patient had common type ALCL. The neoplastic cells in all three patients were ALK positive; however these patients died within months of diagnosis. Leukemic phase ALCL is rare, and behaves in an aggressive manner. Some, but not all, cases in the literature presenting with peripheral blood involvement had small cell variant ALCL, as seen in two of our cases. The leukemic phase of ALCL should be considered when a T-cell leukemia with unusual morphologic features is encountered.

Primary cerebral ALK-1-positive anaplastic large cell lymphoma in a child. Case report and literature review

A 4-year-old African American male was referred to the Pediatric Neurosurgery Service for evaluation of new onset seizures and worsening mental status. An MRI of the brain revealed a pineal region mass with diffuse leptomeningeal enhancement and compression of the basilar cisterns. A biopsy of the brain revealed histologic and immunophenotypic findings characteristic of ALK-1+ anaplastic large cell lymphoma (ALCL). ALCL rarely occurs in the central nervous system and poses a significant diagnostic challenge often leading to a delay in the initiation of appropriate treatment. We describe a case of a rapidly deteriorating clinical course in a child with central nervous system ALCL and review the current literature on ALCL occurring in the central nervous system.

Primary systemic anaplastic large cell lymphoma in a single Korean institution: clinical characteristics and treatment outcome

Despite advances in the characterization of anaplastic large cell lymphoma (ALCL), little data is available on Asian patients. We report here upon single Korean institution's experience regarding the clinical characteristics and outcomes of ALCL. We performed a retrospective study of 32 adults with ALCL. Most of the patients received anthracycline-based chemotherapy. Ann Arbor stage III-IV, B symptoms, high-intermediate/ high International Prognostic Index (IPI), and extranodal disease at diagnosis were present in 56%, 44%, 41%, and 63%, respectively. Compared with Western studies, the male/female ratio (4.3) was markedly higher and skin (9%) and bone involvement (9%) were less frequent. The staining results for anaplastic lymphoma kinase were positive in 6 (33%) of 18 cases available. The complete response (CR) rate was 62% (95% CI, 44-80%). With a median follow-up of 51.0 months, 5 yr overall survival was 40+/-11%. The 3 yr relapse-free survival for the 18 patients who achieved CR was 74+/-12%. Age, performance status, lactate dehydrogenase, extranodal disease sites number, and IPI were correlated with treatment response and survival. Our data suggest that Korean ALCL patients appear to have a higher male/female ratio, less frequent skin/bone involvement, and lower CR rate compared with those of Western studies.

The use of immunohistochemistry in the differential diagnosis of tumors of the testis and paratestis

Although most testicular and paratesticular tumors can be recognized by their light microscopic features, some raise significant differential diagnostic questions. Immunohistochemical staining has proved of significant value in this situation. There is still a role for the traditional markers, including placental-like alkaline phosphatase and alpha-fetoprotein, but newer markers provide additional support and often have greater sensitivity and specificity for many diagnoses. OCT4 is virtually 100% sensitive and specific for seminoma, embryonal carcinoma, and intratubular germ cell neoplasia, unclassified type. Inhibin-alpha, among testicular tumors, is limited to those in the sex cord-stromal category or those having adrenocortical-type differentiation (testicular tumor of the adrenogenital syndrome) or of trophoblastic lineage. Calretinin is another positive marker for the sex cord-stromal tumors but has less specificity. Additional markers, including differential cytokeratins, c-kit, CD30, epithelial membrane antigen, S-100, melan-A, and others, are useful in specific situations. This article reviews the application of immunohistochemical markers for a number of differential diagnostic considerations in the testis and paratestis categorized according to their light microscopic patterns.

Clinicopathologic and Prognostic Significance of Cytotoxic Molecule Expression in Nodal Peripheral T-Cell Lymphoma, Unspecified

Cytotoxic molecules (CMs) are apoptosis-inducing molecules that are present in azurophilic cytoplasmic granules of T lymphocytes. Expression of TIA-1 and granzyme B was examined for 100 cases of nodal peripheral T-cell lymphoma, unspecified (PTCL-U) to assess clinicopathologic significance of CM. Forty-one were positive for at least one CM. Patients with CM-positive PTCL-U showed younger onset (median, 55 years vs. 64 years, P = 0.01) and less male predominance (male:female ratio, 21:20 vs. 44:15, P = 0.02). CM-positive PTCL-U was significantly associated with several clinical factors to indicate poor prognosis, in comparison with CM-negative PTCL-U, such as poorer performance status (P = 0.006), more frequent B-symptoms (68% vs. 35%, P = 0.002), higher serum lactate dehydrogenase levels (P = 0.003), and more frequent extranodal involvement, particularly bone marrow involvement (33% vs. 9%, P = 0.004). Epstein-Barr virus was mostly found in CM-positive PTCL-U (51% vs. 2%, P < 0.0001). The CM-positive group showed higher distribution of the International Prognostic Index (P = 0.009) and the Prognostic Index for T-cell lymphoma (P = 0.004) scores than CM-negative group. Complete remission rate was 30% for the former but 63% for the latter. Overall survival of CM-positive PTCL-U was significantly lower than that of CM-negative patients (P = 0.004). Multivariate analyses confirmed that CM expression is a significant prognostic factor, independent from other clinical factors or prognostic index scores. These findings suggest that nodal CM-positive PTCL-U show distinct clinicopathologic characteristics among the current category of PTCL-U.

High expression of Mcl-1 in ALK positive and negative anaplastic large cell lymphoma

AIM

To gain more insight into the genes involved in the aetiology and pathogenesis of anaplastic large cell lymphoma (ALCL).

METHODS

Serial analysis of gene expression (SAGE) was undertaken on the CD4+ALK+ (anaplastic lymphoma kinase positive) ALCL derived cell line Karpas299 and as comparison on CD4+ T cells. Quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry were performed on five ALCL derived cell lines and 32 tissue samples to confirm the SAGE data.

RESULTS

High expression of Mcl-1 was seen in the Karpas299 cell line, whereas the two other antiapoptotic Bcl-2 family members, Bcl-2 and Bcl-X(L), were not detected in the SAGE library. Quantitative RT-PCR confirmed the high expression of Mcl-1 mRNA and low expression of Bcl-2 and Bcl-X(L) in Karpas299 and in four other ALCL cell lines. To expand on these initial observations, primary tissue samples were analysed for Mcl-1, Bcl-X(L), and Bcl-2 by immunohistochemistry. All 23 ALK+ and nine ALK- ALCL cases were positive for Mcl-1. Bcl-2 and Bcl-X(L) were expressed infrequently in ALK+ ALCL cases, but were present in a higher proportion of ALK- ALCL cases.

CONCLUSION

The consistent high expression of Mcl-1 in ALK+ and ALK- ALCL suggests that Mcl-1 is the main antiapoptotic protein in this disease. The high frequency of Mcl-1, Bcl-2, and Bcl-X(L) positive ALCL cases in the ALK- group compared with the ALK+ group indicates that ALK induced STAT3 activation is not the main regulatory pathway in ALCL.

Anaplastic large cell lymphoma with ALK expression and presence of the t(2;5) translocation in a 5-month-old infant

Anaplastic large cell lymphoma (ALCL) is a well-recognized subtype of non-Hodgkin lymphoma in childhood. Several series report experience with the diagnosis and management of pediatric ALCL, the average age at diagnosis being 8 to 16 years, with a reported range of 1 to 15 years. We present a case of ALCL affecting a 5-month-old infant in whom the diagnosis was confirmed by the nuclear and cytoplasmic immunohistochemical expression of ALK1, in addition to the presence of classical t(2;5)(p23;q35) translocation detected using reverse transcriptase-polymerase chain reaction. This is the youngest case of ALCL thus far reported and hence expands the spectrum of infantile lymphoproliferative disorders.

Case of B-cell lymphoma with rearrangement of the BCL1, BCL2, BCL6, and c-MYC genes

We managed a peculiar case of lymphoma showing immunohistochemical overexpression of cyclin D1. At initial examination the patient had meningeal lymphomatosis and general lymphadenopathy. Histologic examination of biopsy specimens of inguinal lymph nodes showed tumor cells and vague nodular growth resembling lymphoblasts. The results of flow cytometric analysis were positive for CD10, CD20, CD103, and immunoglobulin G (IgG) and Ig kappa and were negative for CD5, CD23, and terminal deoxynucleotidyl transferase activity. Results of immunohistochemical analysis of paraffin-embedded specimens were positive for cyclin D1 and Bcl2 in the tumor cells. Sixty percent of tumor cells had positive results for MIB1/Ki67. Cytogenetic and molecular studies revealed tumor cells simultaneously had t(14;18)(q32;q21), t(11;22)(q13;q11), t(8;14)(q24;q32), and t(3;14)(q27;q32) with the rearrangement of BCL1, BCL2, BCL6, and c-MYC genes. Lymphadenopathy showed a quick and complete response to doxorubicin-containing systemic chemotherapy with rituximab, but the central nervous system disease progressed and killed the patient.

ALK-negative anaplastic large-cell lymphoma demonstrates similar poor prognosis to peripheral T-cell lymphoma, unspecified

AIMS

Anaplastic large cell lymphoma (ALCL) is classically considered a clinicopathological entity separate from other nodal mature T-cell lymphomas (TCL). Recently, the anaplastic lymphoma kinase (ALK) protein was shown to identify a subgroup of nodal ALCL with an excellent prognosis, whereas ALK-negative ALCLs are more heterogeneous. The aim of this study was to investigate the clinicopathological parameters in relation to clinical behaviour of ALK-negative ALCL compared with other nodal mature TCL, i.e. peripheral TCL, unspecified (PTCL-NOS) and angioimmunoblastic lymphoma (AILT).

METHODS AND RESULTS

Clinicopathological data of ALK-positive (n = 28) and ALK-negative (n = 46) ALCL; PTCL-NOS (n = 47); and AILT (n = 12) were analysed for their prognostic significance. While ALK-positive ALCL shows favourable clinical features and a good prognosis, ALK-negative ALCL, PTCL-NOS and AILT are all associated with high age groups, advanced disease stage, and poor prognosis (<45% 5-year survival). In multivariate analysis of overall survival time, performed in the combined group of ALK-negative nodal mature T-cell lymphomas, only age and the International Prognostic Index (IPI) remained independent prognostic parameters, while lymphoma subtype (ALCL versus PTCL-NOS versus AILT) gave no additional information.

CONCLUSIONS

The distinction between ALK-negative ALCL and PTCL-NOS or AILT is of limited clinical relevance as they show comparable poor prognosis. In these lymphoma subtypes, only age and the IPI are of significant prognostic value.

Anaplastic lymphoma kinase proteins in growth control and cancer

The normal functions of full-length anaplastic lymphoma kinase (ALK) remain to be completely elucidated. Although considered to be important in neural development, recent studies in Drosophila also highlight a role for ALK in gut muscle differentiation. Indeed, the Drosophila model offers a future arena for the study of ALK, its ligands and signalling cascades. The discovery of activated fusion forms of the ALK tyrosine kinase in anaplastic large cell lymphoma (ALCL) has dramatically improved our understanding of the pathogenesis of these lymphomas and enhanced the pathological diagnosis of this subtype of non-Hodgkin's lymphoma (NHL). Likewise, the realisation that a high percentage of inflammatory myofibroblastic tumours express activated-ALK fusion proteins has clarified the causation of these mesenchymal neoplasms and provided for their easier discrimination from other mesenchymal-derived inflammatory myofibroblastic tumour (IMT) mimics. Recent reports of ALK expression in a range of carcinoma-derived cell lines together with its apparent role as a receptor for PTN and MK, both of which have been implicated in tumourigenesis, raise the possibility that ALK-mediated signalling could play a role in the development and/or progression of a number of common solid tumours. The therapeutic targeting of ALK may prove to have efficacy in the treatment of many of these neoplasms.

A case of primary cutaneous anaplastic large cell lymphoma with variant anaplastic lymphoma kinase translocation

Anaplastic lymphoma kinase (ALK) is frequently observed in systemic anaplastic large cell lymphoma (ALCL), mostly in childhood or adolescence, but only rarely in primary cutaneous cases. We report a case of primary cutaneous ALCL (pcALCL) with cytoplasmic ALK expression. A 54-year-old woman with an ulcerative tumour on her forehead was admitted to our hospital. Histologically, there was an infiltrate consisting of atypical large lymphocytes and small lymphocytes in the dermis and fat tissue. Southern blot analysis showed monoclonal T-cell receptor Cbeta1 gene rearrangement. Atypical large lymphocytes were positive for CD30, CD4 and CD25, and negative for CD3 and CD79a. They were also positive for ALK only in the cytoplasm, and neurophosmin (NPM)-ALK fusion transcript was not detected by reverse transcription-polymerase chain reaction. This suggested that the translocation partner of the ALK gene in this case was different from NPM (variant translocation). The tumour on the forehead resolved in 1 month after biopsy. Nodular lesions recurred on the right knee, and were histologically identical with the forehead lesion. Our case suggests the existence of a subgroup with variant ALK translocation in pcALCL; examining NPM-ALK translocation in each case with ALK expression should be useful to characterize the disease further.

Three children with CD30 cutaneous anaplastic large cell lymphomas bearing the t(2;5)(p23;q35) translocation

Since its discovery in CD30(+) anaplastic large cell lymphomas, the t(2;5)(p23;q35) translocation has shown a high degree of association with nodal disease, younger patient age, and better prognosis. Furthermore, primary cutaneous CD30(+) anaplastic large cell lymphomas rarely manifests the t(2;5) translocation. We present three cases of this disease that occurred in children, bore the t(2;5) translocation, and had excellent outcomes, but presented cutaneously. Two of these lesions were primary skin lymphomas. Review of the available literature in conjunction with these three cases suggests that the t(2;5) translocation may be more strongly associated with younger patient age and favorable outcomes rather than nodal versus cutaneous site of presentation.

Absence of Epstein-Barr virus in anaplastic large cell lymphoma: a study of 64 cases classified according to World Health Organization criteria

The frequency of Epstein-Barr virus (EBV) in anaplastic large cell lymphoma (ALCL) has been controversial. The interpretation of previous studies is complicated by the use of nonuniform EBV detection methods and the inclusion of cases of CD30-positive diffuse large B-cell lymphoma and so-called "ALCL, Hodgkin-like," as defined in the Revised European-American Lymphoma classification scheme. In the current World Health Organization (WHO) classification system, both of these tumors are excluded from the ALCL category. Also, recently developed antibodies (eg, the antibody specific for PAX-5/B-cell-specific activator protein [BSAP]) provide new, sensitive tools for identifying neoplasms of B-cell lineage that can morphologically resemble ALCL. In this study we evaluated 64 cases of ALCL of T- or null-cell lineage, defined according to the WHO classification system, for the presence of EBV. All tumors were negative for B-cell antigens, including PAX-5/BSAP and CD20 or CD79a. The study group included 27 (42%) anaplastic lymphoma kinase (ALK)-positive (18 T-cell and 9 null-cell) and 37 (58%) ALK-negative (30 T-cell and 7 null-cell) tumors analyzed by in situ hybridization for EBV-encoded RNA (EBER) or immunohistochemistry for EBV-latent membrane protein type 1. All 64 cases were negative for EBV. We conclude, based on the current definition of ALCL in the WHO classification, there is no role for EBV in ALCL arising in Western patients. We suggest that published reports of EBV in a small proportion of ALCL cases in Western patients can be explained by the inclusion of tumors no longer considered to be in the current classification of ALCL, such as CD30-positive anaplastic tumors of B-cell origin.

Common ALK gene rearrangement in Asian CD30+ anaplastic large cell lymphoma: an immunohistochemical and fluorescence in situ hybridisation (FISH) study on paraffin-embedded tissue

AIMS

The most common recurrent genetic aberration in anaplastic large cell lymphoma (ALCL) is translocation involving the ALK gene that results in ectopic expression of ALK protein in lymphoid tissue. This study aims to investigate the frequency of ALK gene rearrangement in a series of Asian ALCL.

METHODS

ALK gene rearrangement was detected by immunostaining of ALK protein and fluorescence in situ hybridisation (FISH) targeting at the 2p23 region.

RESULTS

The expression of ALK protein was detected in 24/34 (71%) of the cases, and it was significantly higher in childhood cases (100%) when compared to adult cases (47%). The analyses by FISH were consistent with the results from immunostaining of ALK protein, but the analyses were only successful in 15/34 (44%) cases. FISH analyses detected extra copies of ALK gene in three cases, including one case that expressed ALK protein and showed 2p23 rearrangement.

CONCLUSIONS

The current series revealed a high frequency of ALK gene rearrangement, especially in the children. Immunostaining of ALK protein is a reliable indication of ALK gene rearrangement, and is superior to FISH. However, FISH analysis is useful in detecting other genetic aberrations that are not related to ALK gene rearrangement.

Detection of a subset of CD30+ anaplastic large cell lymphoma by interphase fluorescence in situ hybridization

T/null-cell anaplastic large cell lymphoma (ALCL) is a morphologically and clinically heterogeneous group of non-Hodgkin's lymphoma; to date several morphologic variants have been described on histologic specimens. However, the cytologic features of these variants in the fine-needle aspiration (FNA) specimens have not been well evaluated. The t(2;5)(p23;q35) has been identified in a subset of T/null-ALCL and is known to be associated with a favorable prognosis. We reviewed the cytomorphologic characteristics in 24 FNA specimens of ALCL. In all cases, the diagnosis was confirmed on histologic specimens, and immunohistochemical studies for anaplastic lymphoma kinase (ALK) protein expression were performed on the aspirates. The presence of ALK breakpoints were evaluated in nine cases, using a DNA break-apart probe on chromosome 2 covering the ALK gene by fluorescence in situ hybridization (FISH) techniques. Two hundred cells per case were examined. The results were expressed as the percentage of cells containing more than two signals of chromosome 2 to the total number of cells counted. FNA sites included lymph nodes (20), lung (2), breast (1), and soft tissue (1). The median age of the patients was 56 yr (range, 17-75 yr). Twenty cases had systemic involvement; in four cases, skin was the primary site with secondary involvement of the lymph nodes. All cases were CD30(+) by immunohistochemistry; 20 were of T-cell phenotype and 4 were null cell type. The cytologic evaluation revealed typical anaplastic morphology (common type) with many "hallmark cells" in 16 (67%) cases. Other morphologic variants identified were small cell pattern in five cases, monomorphic pattern in two cases, and lymphohistiocytic pattern in one case. FISH studies showed that six (66.7%) of nine cases had at least two signals of chromosome 2, consistent with ALK breakpoints. With careful cytomorphologic evaluation in conjunction with appropriate immunohistochemical studies, a diagnosis of ALCL can be confidently made in the FNA specimens in the cellular aspirates and its morphologic variants also can be recognized. Furthermore, the FNA specimen is suitable in detecting ALK breakpoints by FISH study, permitting rapid identification of a subset of patients with ALCL, who may have a favorable prognosis. Using a commercially available probe, detection of ALK breakpoints in the FNA specimens is simple and can be a useful diagnostic adjunct in cases where distinction from other lymphomas or lymphoid lesions is morphologically difficult.

ALK+, CD30-, CD20- large B-cell lymphoma containing anaplastic lymphoma kinase (ALK) fused to clathrin heavy chain gene (CLTC)

Pathological features and genomic basis of a rare case of ALK(+), CD30(-), CD20(-) large B-cell lymphoma were analyzed. A 36-year-old Japanese female was admitted because of lumbago and constitutional symptoms. Physical examination and laboratory tests showed anemia (hemoglobin, 7.5 g/dL), mild hepatosplenomegaly, and immunoglobin G (IgG) lambda-type monoclonal gammopathy (IgG, 2782 mg/dL). The lymphoma spread exclusively in extranodal sites such as bone marrow, liver, spleen, ovary, and muscle. Biopsy specimens obtained from the ovary showed monomorphic proliferation of large immunoblastic cells with basophilic cytoplasm, round-shaped nuclei with a high nuclear to cytoplasmic ratio, and prominent single nucleolus. Immunostaining with anti-anaplastic lymphoma kinase (ALK) antibody, ALK1, showed finely granular cytoplasmic staining pattern. These cells were also positive for epithelial membrane antigen, CD4, CD19, CD38, CD138, cytoplasmic IgG, and lambda chain, but negative for CD30 (Ber-H2), CD56, CD57, and other T- and B-cell markers. Southern blot analyses revealed that Ig heavy and lambda light chain genes, but not T-cell receptor (TCR) beta gene, were clonally rearranged. Chromosomal analyses by conventional G-banding, spectral karyotyping, and fluorescence in situ hybridization showed complex abnormality involving 2p23, and chromosome 2 was translocated to chromosome 17. As 2;17 translocation resulting in the fusion of clathrin heavy chain (CLTC) gene with ALK was previously reported in inflammatory myofibroblastic tumor, we performed reverse transcriptase-polymerase chain reaction and demonstrated that the lymphoma cells contained CLTC-ALK fusion transcript. Under the diagnosis of ALK(+), CD30(-), CD20(-) large B-cell lymphoma, she was treated with conventional combination chemotherapies. However, the lymphoma was primarily chemotherapy resistant, and the patient died 11 months after admission. We consider that this case confirms the existence of ALK(+), CD30(-), CD20(-) large B-cell lymphomas proposed by Delsol et al. (16) and further provides relevant information regarding their clinicopathological features and cytogenetics.

Epstein-Barr virus-associated anaplastic large cell variant of diffuse large B-cell-type non-Hodgkin's lymphoma with concurrent p53 protein expression

In the new World Health Organization (WHO) classification of malignant lymphoma, anaplastic large cell lymphoma of B-cell phenotype is classified either as the anaplastic large cell variant of diffuse large B-cell lymphoma or as Hodgkin's lymphoma. A 71-year-old Japanese man developed fever and generalized lymphadenopathy. Biopsy of the right axillary node revealed morphology of malignant lymphoma in which large cells with abundant cytoplasm and pleomorphic nuclei were scattered among small lymphocytes. Immunostaining with various monoclonal antibodies revealed the large cells to be CD79+, CD20/L26+, CD45RO/UCHL-(1-), CD3-, CD10-, CD30+, NPM/ALK-, EMA-, CD15-, and bcl-(2-). Amplification of the J region of the immunoglobulin heavy chain by polymerase chain reaction revealed a single rearranged band. Therefore the diagnosis of anaplastic large cell variant of diffuse large B-cell lymphoma, stage IIIB, was made from the standpoint of the new WHO classification of malignant lymphoma. Biopsy led to findings of Epstein-Barr virus (EBV)-associated lymphoma with positive in situ hybridization results for EBV small RNAs, positive results of immunostaining with EBV latent membrane 1 antibody, and negative results of immunostaining with Epstein-Barr nuclear antigen 2. Results of immunostaining of the mass with p53 antibody also were positive for lymphoma cells. The findings in this case may suggest a close relationship between p53 expression and latent EBV infection.

Phenotypic analysis of peripheral T/NK cell lymphoma: study of 408 Japanese cases with special reference to their anatomical sites

The World Health Organization (WHO) classification of malignant lymphoma presented a list of disease entities well defined by clinical, immunological and genetic features. Therefore, the current diagnosis of peripheral T/NK-cell lymphomas (PTNKLs) essentially requires the inclusion of anatomical sites of disease and phenotypical features. We analyzed 408 Japanese cases of PTNKLs in order to clarify the relationship between anatomical sites of disease and phenotypical features and to translate the functional subsets of T and NK cells into their diagnoses for further understanding lymphomatic biology. The T/NK-cell lymphoma entities were allocated into three categories: (i) cytotoxic memory T-cell and/or NK-cell lymphoma (n = 151) consisting of extranodal NK/T-cell tumors other than mycosis fungoides (MF); (ii) non-cytotoxic memory T-cell lymphoma (n = 142) consisting of nodal and cutaneous tumors such as angioimmunoblastic T-cell lymphoma, adult T-cell lymphoma/leukemia and MF; and (iii) anaplastic lymphoma kinase positive anaplastic large cell lymphoma (n = 110) that has unique features and might be regarded as cytotoxic 'naive' T-cell lymphoma. Overall, these three categories were significantly correlated with age of onset, anatomical sites, the level of expression of cytotoxic molecules and CD45RO, and association with Epstein-Barr virus. This concept might provide a new insight enabling further understanding of the interrelationships among WHO T/NK-cell disease entities.

ALK-negative systemic anaplastic large cell lymphoma: differential diagnostic and prognostic aspects--a review

Anaplastic large cell lymphoma (ALCL) can be divided into two major groups. The first is a spectrum of CD30+ T-cell lymphoproliferative disorders including primary cutaneous ALCL and lymphomatoid papulosis, usually affecting older patients but characterized by an excellent prognosis. The second is systemic nodal ALCL, which on the basis of genetic and immunophenotypic features combined with clinical parameters can be divided into two subgroups: anaplastic lymphoma kinase (ALK)-positive and ALK-negative systemic ALCL. ALK expression, usually the result of a t(2;5) translocation, correlates with the expression of other markers such as EMA and a cytotoxic phenotype, and is strongly related to younger age groups, lower international prognostic index (IPI) risk groups, and a good prognosis. ALK-negative ALCL, however, shows a more heterogeneous immunophenotype and clinical behaviour, and prognostic parameters are needed to determine treatment strategies in individual patients. Besides clinical parameters included in the IPI, recent studies have pointed out several biological prognosticators of potential value, such as the percentage of tumour-infiltrating activated cytotoxic T-lymphocytes. The expression of proteins involved in the execution or regulation of apoptosis, such as activated caspase 3, Bcl-2, and PI9, was also found to be strongly related to clinical outcome. These studies indicate that inhibition of the apoptosis cascade in particular is an important mechanism that can explain the poor clinical outcome in therapy refractory ALCL. Functional studies are required to investigate whether disruption of one or more of the apoptosis pathways is the major factor in the fatal outcome of the disease and whether apoptosis resistance based on inhibition of one pathway can be overcome by activating another pathway that is still intact.

Primary anaplastic large cell lymphoma of the central nervous system: prognostic effect of ALK-1 expression

Anaplastic large cell lymphoma (ALCL) rarely occurs in the central nervous system. Although defined by its composition of large, pleomorphic, CD30-positive lymphocytes, ALCL is heterogeneous. Most are T cell but some are null cell. Most but not all have a characteristic 2:5 translocation producing the fusion protein ALK-1, which is reliably detected by immunohistochemistry. In systemic ALCL, ALK-1 expression correlates with young patient age and a favorable prognosis. Herein we report four new cases of primary central nervous system ALCL from the Mayo Clinic and incorporate additional data from five previously published cases. ALK-1 expression was determined in all nine tumors. Patient age was 4-66 years (mean 29 years) with a bimodal distribution: 6 < or = 22 years, 3 > or = 50 years. Six were female. Tumors were mostly supratentorial, five were multifocal, and seven had involvement of dura or leptomeninges. Seven tumors were T cell, two were null cell, and five of nine were ALK-1 immunopositive. Total mortality was six of nine. Three patients, 4-18 years of age (mean 13 years), were alive at 4.8-6.1 years postdiagnosis; these tumors were all ALK positive. Five patients, 13-66 years of age (mean 43 years), died of tumor 4 days to 11 weeks postdiagnosis; four of five of these tumors were ALK negative. One 10-year-old child with an ALK-positive tumor died of sepsis, but in remission. Central nervous system ALCL is aggressive. Our study suggests that a better outcome may be associated with young age and ALK-1 positivity, prognostic parameters similar to systemic ALCL.

Neutrophil-rich anaplastic large cell lymphoma presenting in the skin

A neutrophil-rich anaplastic large cell lymphoma (ALCL) presented in the skin of a 47-year-old Japanese woman. The solitary cutaneous lesion was an eroded, 10-mm, dome-shaped nodule involving the skin of her left upper arm. Histologically, it showed a proliferation of pleomorphic, anaplastic, large tumor cells with nuclei of various shapes, including embryo-shaped, Reed-Sternberg cell-like binucleated, and wreath-shaped multiple nuclei, in the dermis and subcutaneous tissues. There was an admixture of neutrophils ranging from about 30% to more than 50% per field. Immunophenotypically, the neoplastic cells were positive for CD30, CD4, leukocyte common antigen, anaplastic lymphoma kinase-1, epithelial membrane antigen, and granzyme B. She had no peripheral neutrophilia. The lesson was excised, and the site on the left upper arm was irradiated. Six and a half months after diagnosis, however, swelling of a left axillary lymph node appeared; it also showed a proliferation of anaplastic large tumor cells admixed with numerous neutrophils ranging from about 25% to more than 60% per field. Southern blot analysis of T-cell receptor gene rearrangement revealed a clonal band. The patient was treated with six courses of cyclophosphamide, doxorubicin, vincristine, and prednisolone chemotherapy with complete remission. Seventeen cases of neutrophil-rich ALCL arising in the skin, lymph node, muscle, testis, and skull bone were reviewed. This form may possibly be induced by trauma or irritation of conventional ALCL, although the true mechanism for the infiltration of neutrophils is still unclear.

A case of anaplastic large cell lymphoma associated with Epstein-Barr virus infection, representing clinicopathological features of malignant histiocytosis

An 82-year-old woman was admitted with fever and anorexia. Aggravated pancytopenia and liver dysfunction suggested the presence of disseminated intravascular coagulation. The serum ferritin level increased to 9,100 ng/ml. Bone marrow aspiration showed an increase of histiocytes with phagocytosis and a diagnosis of hemophagocytic syndrome was made. Symptomatic therapy was performed because of her deteriorated general condition. She died of multiple organ failure, 32 days after admission. Autopsy revealed swollen lymph nodes with proliferation of large neoplastic cells containing rich cytoplasm and pleomorphic and multi-segmented large nuclei. The immunophenotype of the neoplastic cells was LCA-, CD3-, CD5-, CD 20-, CD79a-, UCHL1-, MT1-, CD15-, p80-. Neoplastic cells were positive for CD30, mainly in Golgi apparati, and also positive for EBV-encoded small nonpolyadenylated RNAs (EBER). This case was diagnosed as anaplastic large cell lymphoma (ALCL) associated with hemophagocytic syndrome. It was estimated that Epstein-Barr virus had played an important role in the development of ALCL in the present case.

Molecular biology of anaplastic lymphoma kinase-positive anaplastic large-cell lymphoma

Anaplastic large-cell lymphoma (ALCL) provides an excellent example of how molecular insights into tumor pathogenesis are influencing and improving tumor classification. ALCL was described initially as a subtype of T-cell/null-cell lymphoma characterized by unusual tumor cell morphology and the expression of CD30. However, it was soon recognized that a subset of ALCLs contained chromosomal translocations involving anaplastic lymphoma kinase (ALK), a novel receptor tyrosine kinase gene. These rearrangements create chimeric genes encoding self-associating, constitutively active ALK fusion proteins that activate a number of downstream effectors, including phospholipase C-gamma, phosphoinositol 3'-kinase, RAS, and signal transducer and activator of transcription proteins, all of which seem potentially important in cellular transformation. Not all tumors classified as ALCLs have ALK rearrangements and, conversely, ALK rearrangements occur in lymphomas of widely varying morphology. Hence, only molecular markers can reliably identify ALK+ ALCL. The importance of doing so is reflected by clinical studies suggesting that ALK+ ALCLs have a significantly better prognosis than other aggressive peripheral T-cell or B-cell lymphomas, including ALK- ALCLs. The unique molecular pathogenesis of ALK+ ALCL is likely to lead to novel therapeutic approaches directed at specific inhibition of ALK or downstream effectors.

Identification of novel fusion partners of ALK, the anaplastic lymphoma kinase, in anaplastic large-cell lymphoma and inflammatory myofibroblastic tumor

ALK-positive anaplastic large-cell lymphoma (ALCL) has been recognized as a distinct type of lymphoma in the heterogeneous group of T/Null-ALCL. While most of the ALK-positive ALCL (ALKomas) are characterized by the presence of the NPM-ALK fusion protein, the product of the t(2;5)(p23;q35), 10-20% of ALKomas contain variant ALK fusions, including ATIC-ALK, TFG-ALK, CLTC-ALK (previously designated CLTCL-ALK), TMP3-ALK, and MSN-ALK. TMP3-ALK and TMP4-ALK fusions also have been detected in inflammatory myofibroblastic tumors (IMTs), making clear that aberrations of the ALK gene are not associated exclusively with the pathogenesis of ALK-positive ALCL. Here we report results of molecular studies on two lymphoma cases and one IMT case with variant rearrangements of ALK. Our study led to the detection of the CLTC-ALK fusion in an ALCL case and to the identification of two novel fusion partners of ALK: ALO17 (KIAA1618), a gene with unknown function, which was fused to ALK in an ALCL case with a t(2;17)(p23;q25), and CARS, encoding the cysteinyl-tRNA synthetase, which was fused to ALK in an IMT case with a t(2;11;2)(p23;p15;q31). These results confirm the recurrent involvement of ALK in IMT and further demonstrate the diversity of ALK fusion partners, with the ability to homodimerize as a common characteristic.

Hodgkin's lymphoma: the pathologist's viewpoint

Despite its well known histological and clinical features, Hodgkin's lymphoma (HL) has recently been the object of intense research activity, leading to a better understanding of its phenotype, molecular characteristics, histogenesis, and possible mechanisms of lymphomagenesis. There is complete consensus on the B cell derivation of the tumour in most cases, and on the relevance of Epstein-Barr virus infection and defective cytokinesis in at least a proportion of patients. The REAL/WHO classification recognises a basic distinction between lymphocyte predominance HL (LP-HL) and classic HL (CHL), reflecting the differences in clinical presentation and behaviour, morphology, phenotype, and molecular features. CHL has been classified into four subtypes: lymphocyte rich, nodular sclerosing, with mixed cellularity, and lymphocyte depleted. The borders between CHL and anaplastic large cell lymphoma have become sharper, whereas those between LP-HL and T cell rich B cell lymphoma remain ill defined. Treatments adjusted to the pathobiological characteristics of the tumour in at risk patients have been proposed and are on the way to being applied.

Association of expression of CD44v6 with systemic anaplastic large cell lymphoma: comparison with primary cutaneous anaplastic large cell lymphoma

CD44 is a ubiquitous multifunctional cell surface adhesion molecule family. High expression of the standard form, CD44s (CD44), and its variant form, CD44v6, has been reported to be associated with tumor dissemination in non-Hodgkin lymphoma. To evaluate the potential role of CD44 and/or CD44v6 in different entities of anaplastic large cell lymphoma (ALCL), 30 cases of systemic ALCL (sALCL; 20 cases) and primary cutaneous ALCL (cALCL; 10 cases) were compared for expression of CD44 and CD44v6 by immunohistochemical staining. Expression of CD44v6 also was analyzed with respect to expression of anaplastic lymphoma kinase (ALK) in sALCL. No difference of CD44 expression was noted between sALCL and cALCL In contrast, expression of CD44v6 was found in 18 (90%) of sALCL cases and in 5 (50%) of cALCL cases. There was no correlation between expression of CD44v6 and expression of ALK in sALCL. These results indicate that expression of CD44v6 rather than CD44 correlates with sALCL. Furthermore, these results suggest that CD44v6 and ALK may be independent predictors of risk for the systemic phenotype of ALCL.