Cutaneous T-cell and NK-cell lymphomas: the WHO-EORTC classification and the increasing recognition of specialized tumor types

Epstein-Barr virus: dermatologic associations and implications: part II. Associated lymphoproliferative disorders and solid tumors

Epstein-Barr virus (EBV) was the first human virus to be associated with oncogenesis. Over the past few decades, cumulative research has revealed that latent EBV infection may be implicated in the pathogenesis of a heterogeneous group of lymphoproliferative disorders and malignancies occurring in both immunocompetent and immunocompromised hosts. Many of these diseases have either primary or secondary cutaneous manifestations. Serologic studies and EBV-encoded RNA in situ hybridization stains have been used to show the association of EBV with disease; while these findings may imply a role, they do not equate with causation. In part II of this continuing medical education review, the salient features of EBV-associated lymphoproliferative disorders and solid tumors are detailed.

TCR-γ expression in primary cutaneous T-cell lymphomas

Primary cutaneous γδ T-cell lymphomas (PCGD-TCLs) are considered a subgroup of aggressive cytotoxic T-cell lymphomas (CTCLs). We have taken advantage of a new, commercially available antibody that recognizes the T-cell receptor-γ (TCR-γ) subunit of the TCR in paraffin-embedded tissue. We have analyzed a series of 146 primary cutaneous T-cell lymphomas received for consultation or a second opinion in the CNIO Pathology Department. Cases were classified according to the World Health Organization 2008 classification as mycosis fungoides (MF; n=96), PCGD-TCLs (n=5), pagetoid reticulosis (n=6), CD30(+) primary cutaneous anaplastic large cell lymphomas (n=5), primary cutaneous CD8 aggressive epidermotropic CTCLs (n=3), primary cutaneous CTCL, not otherwise specified (n=4), and extranodal nasal-type NK/T-cell lymphomas primarily affecting the skin or subcutaneous tissue (n=11). Sixteen cases of the newly named lymphomatoid papulosis type D (LyP-D; n=16) were also included. In those cases positive for TCR-γ, a further panel of 13 antibodies was used for analysis, including TIA-1, granzyme B, and perforin. Clinical and follow-up data were recorded in all cases. Twelve cases (8.2%) were positive for TCR-γ, including 5 PCGD-TCLs, 2 MFs, and 5 LyP-Ds. All 5 PCGD-TCL patients and 1 MF patient died of the disease, whereas the other MF patient and all those with LyP-D were alive. All cases expressed cytotoxic markers, were frequently CD3(+)/CD8(+), and tended to lose CD5 and CD7 expressions. Eight of 12 and 5 of 11 cases were CD30(+) and CD56(+), respectively. Interestingly, 5/12 TCR-γ-positive cases also expressed TCR-BF1. All cases analyzed were negative for Epstein-Barr virus-encoded RNA. In conclusion, TCR-γ expression seems to be rare and is confined to cytotoxic primary cutaneous TCLs. Nevertheless, its expression is not exclusive to PCGD-TCLs, as TCR-γ protein can be found in other CTCLs. Moreover, its expression does not seem to be associated with bad prognosis by itself, as it can be found in cases with good and bad outcomes.

An algorithmic approach to the diagnosis of NK and T cell lymphomas

Lymphomas of natural killer (NK) and T cell lineages are uncommon disorders, although as a group they are more usually encountered in Asia compared to Western populations. In part due to their rarity, diagnosis and classification of T cell lymphomas often pose a challenge to clinicians and pathologists. Although there are morphological features that are characteristic of certain subtypes, correct classification of NK and T cell neoplasms relies heavily on the immunophenotype. With few exceptions, non-random genetic alterations such as translocations are less often seen in T cell neoplasms, adding to the diagnostic difficulty. Given these limitations, pathological diagnosis and classification of NK and T cell lymphomas are anything but straightforward. This paper attempts to present a practical algorithmic approach for the general pathologist who is confronted with these neoplasms.

Flow cytometry and its use in the diagnosis and management of mature lymphoid malignancies

The last decade has seen major advances in flow cytometric immunophenotyping and this has expanded the utility of flow cytometry to investigate the antigens present on normal and neoplastic haematopoietic cells. This review summarizes how flow cytometry is used currently in the diagnosis and management of mature lymphoid malignancies. The establishment of disease-specific phenotypes allows the creation of assays which can detect neoplastic cells with high specificity and sensitivity. Certain lymphoid neoplasms are well defined immunophenotypically, while others are more heterogeneous. The availability of more sophisticated cytometers and a wider selection of antibodies in routine diagnostic laboratories will lead to the resolution of these more complex disease entities.

Early-stage mycosis fungoides variants: case-based review

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma. The diagnosis of classic MF is based on a combination of clinical presentation, histopathology, and T-cell monoclonality detected by molecular studies. However, the diagnosis can be difficult in cases of early MF because of the subtle nature of histologic findings and, in cases of variants of MF, because of the unusual clinical and/or pathologic features. In this review, we presented the most frequent variants of MF at early stage including hypopigmented, folliculotropic, pagetoid reticulosis, unilesional, granulomatous, and ichthyosis forms. This case-based clinicopathologic review provides the notion that a comprehensive clinicopathologic correlation is of substantial importance to render the diagnosis of MF. In addition, we discuss the role of molecular studies, which are highly sensitive and recently more applicable to routinely processed skin biopsy specimens in the diagnosis of MF.

Extranodal natural killer cell/t-cell lymphoma, nasal type, presenting as cutaneous nodules and a small-bowel perforation

Extranodal natural killer (NK) cell/T-cell lymphoma, nasal type, is a rare aggressive neoplasm, most commonly presenting as a destructive lesion in the nasal cavity and nasopharynx in middle-aged to older adults. About one third of cases present in an extranasal location, commonly involving skin and gastrointestinal tract, and usually occur in the absence of superficial lymphadenopathy. Diagnosis of this malignancy can be missed given its rarity and heterogeneous presentation. We describe a patient with an extranodal NK cell/T-cell lymphoma, nasal type, who was initially diagnosed and treated for a presumed Mycobacterium marinum infection, after biopsies were unrevealing. However, after more serious complications developed, repeat biopsy was performed. An atypical lymphocytic infiltrate was noted, with cells being positive for NK cell/T-cell markers CD2, CD7, and CD3 (subset), as well as for cytotoxic lymphocyte markers perforin, T-cell intracellular antigen, and CD56. In situ hybridization for Epstein-Barr virus-encoded RNA was also positive. This case demonstrates an important diagnostic pitfall of confusing cutaneous involvement by an aggressive NK cell/T-cell lymphoma with an antibiotic-resistant infection. Repeat biopsies and close clinicopathologic correlation are essential for establishment of correct diagnosis.

Anaplastic lymphoma kinase: role in cancer pathogenesis and small-molecule inhibitor development for therapy

Anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase in the insulin receptor superfamily, was initially identified in constitutively activated oncogenic fusion forms - the most common being nucleophosmin-ALK - in anaplastic large-cell lymphomas, and subsequent studies have identified ALK fusions in diffuse large B-cell lymphomas, systemic histiocytosis, inflammatory myofibroblastic tumors, esophageal squamous cell carcinomas and non-small-cell lung carcinomas. More recently, genomic DNA amplification and protein overexpression, as well as activating point mutations, of ALK have been described in neuroblastomas. In addition to those cancers for which a causative role for aberrant ALK activity is well validated, more circumstantial links implicate the full-length, normal ALK receptor in the genesis of other malignancies - including glioblastoma and breast cancer - via a mechanism of receptor activation involving autocrine and/or paracrine growth loops with the reported ALK ligands, pleiotrophin and midkine. This review summarizes normal ALK biology, the confirmed and putative roles of ALK in the development of human cancers and efforts to target ALK using small-molecule kinase inhibitors.

Cutaneous lymphoma incidence patterns in the United States: a population-based study of 3884 cases

There have been no prior large population-based studies focusing on cutaneous lymphomas (CL) in the United States. Using the Surveillance, Epidemiology and End Results (SEER) program data, we analyzed age-adjusted CL incidence rates (IRs) and survival rates by sex and race/ethnicity. There were 3884 CLs diagnosed during 2001-2005. Cutaneous T-cell lymphomas (CTCLs) accounted for 71% (age-adjusted incidence rate [IR] = 7.7/1 000 000 person-years), whereas cutaneous B-cell lymphomas(CBCLs) accounted for 29% (IR = 3.1/1 000 000 person-years). Males had a statistically significant higher IR of CL than females (14.0 vs 8.2/1 000 000 person-years, respectively; male-female IR ratio [M/F IRR] = 1.72; P < .001). CL IRs were highest among blacks and non-Hispanic whites (both 11.5/1 000 000 person-years), followed by Hispanic whites (7.9) and Asian/Pacific Islanders (7.1). The CTCL IR was highest among blacks (10.0/1 000 000 person-years), whereas the CBCL IR was highest among non-Hispanic whites (3.5). Over the past 25 years, the CL IR increased from 5.0/1 000 000 person-years during 1980-1982 to 14.3 during 2001-2003. During 2004-2005, the CL IR was 12.7. This recent apparent change could be incomplete case ascertainment or potential leveling off of IRs. CLs rates vary markedly by race and sex, supporting the notion that they represent distinct disease entities.

A case of CD30+ nasal natural killer/T-cell lymphoma

Extranodal nasal natural killer (NK)/T-cell lymphoma is a very rare lymphoma characterized by strong association with Epstein-Barr virus infection, very aggressive clinical behavior, and poor prognosis. The typical phenotype of neoplastic natural killer cells in this entity is as follows: CD2+, CD56+, surface CD3-, cytoplasmic CD3epsilon+, and cytotoxic granule-associated protein positive. CD30 expression, a phenotype characteristic of anaplastic large-cell lymphomas, is not a typical feature of nasal NK/T-cell lymphomas. We describe the case of a 42-year-old woman with chronic nasal congestion and septal deviation who presented with progressive generalized tender erythematous plaques. A skin biopsy revealed an atypical angiocentric mononuclear cell infiltrate. Strong CD30 and CD3e immunoreactivities were noted in large atypical mononuclear cells within the infiltrate initially suggestive of a CD30+ T-cell lymphoma. However, flow cytometry of the skin lesion indicated that the cells were CD2+, CD4-, CD8-, and lacked surface CD3 more typical of a neoplasm of natural killer cells. Further studies revealed that the cells were CD56+, T-cell-restricted intracellular antigen-1+, and contained Epstein-Barr virus sequences consistent with a nasal-type NK/T-cell lymphoma. High titers of Epstein-Barr virus in the blood, evidence of sinonasal disease, and absence of a T-cell receptor gene rearrangement were additional features consistent with the diagnosis. The patient had a very aggressive clinical course and, despite combination chemotherapy, died 8 months after the onset of skin lesions. This case represents an example of nasal-type NK/T-cell lymphoma with expression of CD30. When presenting in the skin, the phenotypic and morphologic features of this lymphoma may lead to an erroneous diagnosis of a CD30+ large-T-cell lymphoma.

Human natural killer cells

Natural killer (NK) cells were discovered more than 30 years ago. NK cells are large granular lymphocytes that belong to the innate immune system because unlike T or B lymphocytes of the adaptive or antigen-specific immune system, NK cells do not rearrange T-cell receptor or immunoglobulin genes from their germline configuration. During the past 2 decades there has been a substantial gain in our understanding of what and how NK-cells "see," lending important insights into their functions and purpose in normal immune surveillance. The most recent discoveries in NK-cell receptor biology have fueled translational research that has led to remarkable results in treating human malignancy.

Lethal vascular leak syndrome after denileukin diftitox administration to a patient with cutaneous gamma/delta T-cell lymphoma and occult cirrhosis

Denileukin diftitox (Ontak) is an immunotoxin used in the treatment of cutaneous T-cell lymphomas. Vascular leak syndrome is a known complication of this therapy, although the syndrome is most often self-limited. We report the case of a patient with cutaneous gamma/delta (gammadelta) T-cell lymphoma and previous undiagnosed liver disease treated with denileukin diftitox. Just 4 days after initiating drug therapy, the patient developed profound vascular leak syndrome characterized by a rapid fall in his previously normal serum albumin to levels below the limit of detection. The patient then quickly deteriorated into rhabdomyolysis and eventual death. To our knowledge, this is the first report of a death directly related to denileukin diftitox therapy. The purpose of this case is to increase awareness and improve management of patients who are treated with denileukin diftitox with resulting vascular leak syndrome leading to hypoalbuminemia.

Flow cytometric immunophenotyping for hematologic neoplasms

Flow cytometric immunophenotyping remains an indispensable tool for the diagnosis, classification, staging, and monitoring of hematologic neoplasms. The last 10 years have seen advances in flow cytometry instrumentation and availability of an expanded range of antibodies and fluorochromes that have improved our ability to identify different normal cell populations and recognize phenotypic aberrancies, even when present in a small proportion of the cells analyzed. Phenotypically abnormal populations have been documented in many hematologic neoplasms, including lymphoma, chronic lymphoid leukemias, plasma cell neoplasms, acute leukemia, paroxysmal nocturnal hemoglobinuria, mast cell disease, myelodysplastic syndromes, and myeloproliferative disorders. The past decade has also seen refinement of the criteria used to identify distinct disease entities with widespread adoption of the 2001 World Health Organization (WHO) classification. This classification endorses a multiparametric approach to diagnosis and outlines the morphologic, immunophenotypic, and genotypic features characteristic of each disease entity. When should flow cytometric immunophenotyping be applied? The recent Bethesda International Consensus Conference on flow cytometric immunophenotypic analysis of hematolymphoid neoplasms made recommendations on the medical indications for flow cytometric testing. This review discusses how flow cytometric testing is currently applied in these clinical situations and how the information obtained can be used to direct other testing.