Analysis of clonality of atypical cutaneous lymphoid infiltrates associated with drug therapy by PCR/DGGE

Evaluation of clonality from multiple anatomic sites in canine epitheliotropic T cell lymphoma

BACKGROUND

Canine epitheliotropic cutaneous T-cell lymphoma (eCTCL) is thought to represent a disease homologue to human mycosis fungoides (MF). In human MF, neoplastic cells are phenotypically consistent with resident effector memory T cells, a population that remains for an extended period within tissue without circulating. Dogs with eCTCL often present with lesions in multiple locations, raising the question of whether the neoplasm is of the same T-cell subpopulation or not.

OBJECTIVES

To characterize the antigen receptor gene rearrangements of lymphocytes from skin and blood of dogs with eCTCL to determine if neoplastic clones are identical.

ANIMALS

Fourteen dogs with eCTCL.

MATERIALS AND METHODS

Histological and immunohistochemical examination, and PCR for antigen receptor rearrangement (PARR) for T-cell receptor gamma (TRG) performed on multiple cutaneous biopsy samples and blood.

RESULTS

All skin biopsies contained cluster of differentiation (CD)3-positive neoplastic lymphocytes. Within individual dogs, all skin biopsies revealed identical TRG clonality profiles, suggesting that the same neoplastic clone was present in all sites. In the blood, a matching clone was found in six of 14 dogs, a unique clone was observed in nine of 14 dogs, and no clone was detected in two of 14 dogs.

CONCLUSIONS

These findings show that canine eCTCL lesions in multiple locations harbour the same neoplastic clone, neoplastic lymphocytes do not remain fixed to the skin and instead can circulate via blood, differing clones can be identified in skin versus blood, and circulating neoplastic cells can be detected without lymphocytosis.

Cutaneous Reactive B-cell Lymphoid Proliferations

Cutaneous lymphoid hyperplasia (CLH), also known as cutaneous pseudolymphoma, is a spectrum of benign conditions characterized by reactive B- and T-cell cutaneous lymphocytic infiltrates. B-cell lymphoid proliferations are a heterogenous group of non-neoplastic cutaneous diseases that must be histopathologically distinguished from cutaneous B-cell lymphomas. These proliferations can be observed as reactive phenomena to infections, medications, allergens, neoplasms, and more. Further, there are many inflammatory conditions that present with reactive B-cell infiltrates, including actinic prurigo, Zoon balanitis, Rosai-Dorfman, and cutaneous plasmacytosis. This review summarizes multiple cutaneous B-cell lymphoid proliferations within the major categories of reactive and disease-associated CLH. Further we discuss major discriminating features of atypical CLH and malignancy. Understanding the specific patterns of B-cell CLH is essential for the proper diagnosis and treatment of patients presenting with such lesions.

Clonality testing in the lymph nodes from dogs with lymphadenomegaly due to Leishmania infantum infection

INTRODUCTION

In southern European countries, multicentric lymphoma and leishmaniosis are the main differential diagnoses in dogs presented with generalized lymphadenomegaly. The cytological examination is in some cases inconclusive and polymerase chain reaction (PCR) for antigen receptor rearrangement (PARR) has become a common method to confirm or rule out a lymphoproliferative neoplasia. According to the literature, leishmaniosis may lead to clonal arrangements and therefore to a false diagnosis of lymphoma, but this assumption is made from a single leishmania infected dog. Therefore, the objective of this study was to prospectively evaluate results from PARR in dogs with lymphadenomegaly due to clinical leishmaniosis at the moment of diagnosis.

MATERIALS AND METHODS

31 dogs with a diagnosis of leishmaniosis based on the LeishVet guidelines were included in the study. Samples from enlarged lymph nodes were taken for cytological examination, clonality testing and Leishmania infantum PCR.

RESULTS

All 31 dogs had medium to high positive antibody titers against Leishmania spp. and 30/31 had a positive Leishmania PCR from the lymph node. A polyclonal arrangement for B cells (immunoglobulin heavy chain gene) and T cells (T-cell receptor gamma chain gene) antigen receptors was found in 28/31 dogs. Two out of 31 dogs showed a monoclonal arrangement for Ig with high (1:2) and low (1:7) polyclonal background respectively; and one of the 31 dogs showed a monoclonal arrangement for T cell receptor with low (1:3) polyclonal background.

CONCLUSION

Infections with Leishmania infantum resulted in clonal rearrangement, and therefore in a possible false diagnosis of lymphoma, in 3 out of 31 dogs (9.7%). Although, PARR is a useful method to differentiate lymphoma from reactive lymphoid hyperplasia in dogs with leishmaniosis, mono-/biclonal results should be interpreted carefully, especially in the presence of any degree of polyclonal background, and together with other clinicopathological findings.

Generalized fixed drug eruption mimicking CD8+ cutaneous T-cell lymphoma in HIV

We present a case of a widespread fixed drug eruption histologically mimicking CD8 positive cutaneous T-cell lymphoma (CTCL). CTCL has several potential histological and clinical mimics, and accurate diagnosis relies on a combination of clinicopathological correlation and molecular studies. We add generalized fixed drug eruption to the list of possible CTCL mimics.

Clonality Testing in Veterinary Medicine

The accurate distinction of reactive and neoplastic lymphoid proliferations can present challenges. Given the different prognoses and treatment strategies, a correct diagnosis is crucial. Molecular clonality assays assess rearranged lymphocyte antigen receptor gene diversity and can help differentiate reactive from neoplastic lymphoid proliferations. Molecular clonality assays are commonly used to assess atypical, mixed, or mature lymphoid proliferations; small tissue fragments that lack architecture; and fluid samples. In addition, clonality testing can be utilized to track neoplastic clones over time or across anatomic sites. Molecular clonality assays are not stand-alone tests but useful adjuncts that follow clinical, morphologic, and immunophenotypic assessment. Even though clonality testing provides valuable information in a variety of situations, the complexities and pitfalls of this method, as well as its dependency on the experience of the interpreter, are often understated. In addition, a lack of standardized terminology, laboratory practices, and interpretational guidelines hinders the reproducibility of clonality testing across laboratories in veterinary medicine. The objectives of this review are twofold. First, the review is intended to familiarize the diagnostic pathologist or interested clinician with the concepts, potential pitfalls, and limitations of clonality testing. Second, the review strives to provide a basis for future harmonization of clonality testing in veterinary medicine by providing diagnostic guidelines.

Indolent CD8+ lymphoid proliferation of the face with eyelid involvement

In 2007, Petrella et al described a series of patients with clonally restricted, well-differentiated, nonepidermotropic, CD8-dominant lymphocytic infiltrates localized to the facial area. The clinical course described was indolent. A CD8 variant of primary cutaneous pleomorphic T-cell lymphoma has been proposed; however, there are many dissimilar features. The authors encountered 2 patients with CD8⁺ indolent lymphoid proliferation of the face, localized to the eyelid. Both patients were males in their 30s presenting with localized lesions of the eyelids. The biopsies showed an effacing lymphocytic infiltrate that spanned the sampled dermis. The lymphocytes were well differentiated, exhibiting mild nuclear contour irregularity. The infiltrate was predominated by CD8⁺ lymphocytes demonstrating TIA expression. There was a minimal B-cell component in 1 case, whereas another showed a significant degree of B-cell hyperplasia. They both underwent complete excision without recurrence. CD8⁺ indolent lymphoid proliferation has a reproducible clinical and morphologic presentation that warrants categorization as a distinct form of indolent lymphoproliferative disease, preferentially involving older adults with the most common site being the ear, recognizing that the nose, acral surfaces, and eyelids can also be involved.

Selected Inflammatory Imitators of Mycosis Fungoides: Histologic Features and Utility of Ancillary Studies

Mycosis fungoides is the most common primary cutaneous lymphoma; however, it remains a significant diagnostic challenge, in part because of the overlap with several inflammatory dermatoses. Despite advances in immunohistochemistry and molecular diagnostics, false-positive, false-negative, and indeterminate diagnoses are not uncommon. In most cases, the overall balance of morphologic, immunophenotypic, and genetic features must be considered carefully because there are few sensitive and specific clues to the diagnosis. Moreover, an appropriate clinical presentation is essential to the diagnosis and helps to favor or exclude inflammatory/reactive processes. Herein, we discuss 3 important inflammatory dermatoses that may closely simulate mycosis fungoides, and we review the use of ancillary studies in these challenging cases.

Mimics of cutaneous lymphoma: report of the 2011 Society for Hematopathology/European Association for Haematopathology workshop

The Society for Hematopathology and European Association for Haematopathology workshop, from October 27 to 29, 2011, in Los Angeles, CA, exhibited many exemplary skin biopsy specimens with interesting inflammatory changes mimicking features of cutaneous lymphoma. This article reviews features observed in cutaneous lymphoid hyperplasia, cutaneous drug reactions, lupus-associated panniculitis, pityriasis lichenoides, hypereosinophilic syndrome, histiocytic necrotizing lymphadenitis, traumatic ulcerative granuloma with stromal eosinophils, and pigmented purpuric dermatosis, as well as a brief review of the pertinent literature and discussion of submitted conference cases. For the pathologist, it is important to be aware of diagnostic pitfalls as well as the limitations of ancillary testing (eg, clonality studies). Finally, correlation with total clinical information, good communication with clinical colleagues, close clinical follow-up with rebiopsy, and prudent use of laboratory studies are vital and will likely offer the best path toward a correct diagnosis.

Hydrochlorothiazide and cutaneous T cell lymphoma: prospective analysis and case series

BACKGROUND

Mycosis fungoides (MF) and leukemic Sézary syndrome (SS) are the most common cutaneous T cell lymphomas (CTCL), but their etiology remains unknown. After patients were observed with hydrochlorothiazide (HCTZ)-associated CTCL, HCTZ was examined as a putative chronic antigen in a cohort of prospectively staged patients.

METHODS

Demographic and drug exposure data was examined from 1443 confirmed MF and SS patients. Hypertensive CTCL patients were divided into HCTZ users or nonusers for statistical analysis by chi-square and t tests. Causality in a case series was rated by the Naranjo Adverse Drug Reaction Probability Scale.

RESULTS

A total of 815 of 1443 MF and SS patients (56.5%) were hypertensive; 205 (25.2%) were taking HCTZ at initial staging. Comparing stage of patients who were using or not using HCTZ, the most significant difference was between stage I and stage IV (odds ratio of 0.45; 95% confidence interval of 0.25-0.78, P = .003), demonstrating reduced likelihood of being stage IV in patients who were on HCTZ. Seventy-seven percent of the MF patients on HCTZ were stage I. A total of 125 patients of 196 (63.8%) started HCTZ prior to developing CTCL lesions, and 35 of 121 (28.0%) started within 1 year of first skin rash. Thirty-six of 125 patients (28.8%) experienced complete or partial remissions after discontinuing HCTZ. A monoclonal T cell receptor rearrangement was detected more frequently in the hypertensive stage I patients not taking HCTZ as compared with those who were (55.3% vs 69.1%, P = .032). Three patients were rechallenged and developed MF lesions that resolved or improved with discontinuation.

CONCLUSIONS

HCTZ is commonly prescribed and may be a putative antigen in a small subset of early MF patients. Careful drug histories and a trial off medication are warranted.

Tumor heterogeneity: mechanisms and bases for a reliable application of molecular marker design

Tumor heterogeneity is a confusing finding in the assessment of neoplasms, potentially resulting in inaccurate diagnostic, prognostic and predictive tests. This tumor heterogeneity is not always a random and unpredictable phenomenon, whose knowledge helps designing better tests. The biologic reasons for this intratumoral heterogeneity would then be important to understand both the natural history of neoplasms and the selection of test samples for reliable analysis. The main factors contributing to intratumoral heterogeneity inducing gene abnormalities or modifying its expression include: the gradient ischemic level within neoplasms, the action of tumor microenvironment (bidirectional interaction between tumor cells and stroma), mechanisms of intercellular transference of genetic information (exosomes), and differential mechanisms of sequence-independent modifications of genetic material and proteins. The intratumoral heterogeneity is at the origin of tumor progression and it is also the byproduct of the selection process during progression. Any analysis of heterogeneity mechanisms must be integrated within the process of segregation of genetic changes in tumor cells during the clonal expansion and progression of neoplasms. The evaluation of these mechanisms must also consider the redundancy and pleiotropism of molecular pathways, for which appropriate surrogate markers would support the presence or not of heterogeneous genetics and the main mechanisms responsible. This knowledge would constitute a solid scientific background for future therapeutic planning.

Lymphomatoid hypersensitivity reaction to levofloxacin during autologous stem cell transplantation: a potential diagnostic pitfall in patients treated for lymphoma or leukemia

Drug-associated cutaneous lymphomatoid hypersensitivity reactions are rare eruptions that can clinically and microscopically mimic a bona fide lymphomatous process. Clinically, the appearance ranges from papulosquamous to purpuric. Histopathologically, these reactions simulate a wide variety of lymphoma subtypes; the most frequently reported examples resemble mycosis fungoides. We report a 61-year-old female who developed a purpuric eruption prior to engraftment of an autologous hematopoietic stem cell transplant for stage IV mantle cell lymphoma. Skin biopsies showed a superficial perivascular and interstitial infiltrate of large, immature-appearing mononuclear cells associated with spongiosis, papillary dermal edema and erythrocyte extravasation. The cells were immunoreactive for T-cell markers and lacked B-cell marker expression, excluding recurrence of the underlying mantle cell lymphoma as a diagnostic possibility. The cutaneous eruption was temporally linked to levofloxacin administration and resolved after discontinuation of this medication. This is the first report of a lymphomatoid hypersensitivity reaction associated with fluoroquinolone use. The histopathologic features presented in this paper underscore the potential for misdiagnosis of such lesions as lymphoma or acute myeloid leukemia, particularly in the setting of hematopoietic stem cell transplantation for underlying lymphoma or leukemia. Clinical correlation, morphologic comparison to the original malignancy and immunohistochemical studies aid the dermatopathologist in rendering the correct diagnosis.

Atypical cutaneous lymphoid hyperplasia induced by chemotherapy in a patient with advanced colon carcinoma

Some conditions are predisposed to excessive lymphocyte responses, which can progress to a benign condition, ie, atypical cutaneous lymphoid hyperplasia (ACLH), or a malignant lymphoma. Clinical diagnosis of drug-associated pseudolymphoma can be based on a temporal association between drug ingestion and lesion onset followed by resolution without recurrence after discontinuation of drug administration. Herein, we report the case of a 66-year-old man with advanced colon carcinoma with ACLH developed while receiving chemotherapy regimen with oxaliplatin/5-fluorouracil/leucovorin. The authors postulate that chemotherapy can promote an aberrant immune response to an antigen that can be the drug itself or other self-antigens.

Usefulness of flow cytometry in the diagnosis of mycosis fungoides

BACKGROUND

The pathologic evaluation of mycosis fungoides (MF) is a challenging area in dermatopathology.

OBJECTIVE

We sought to determine the usefulness of flow cytometry for the diagnosis of MF from skin biopsy specimens.

METHODS

Skin biopsy specimens from 22 patients with a clinical suggestion for MF were evaluated by 4-color flow cytometry. The results were correlated with the International Society for Cutaneous Lymphoma (ISCL) MF diagnostic score and molecular studies for T-cell receptor gene rearrangement.

RESULTS

A T-cell abnormality by flow cytometry was identified in all 11 patients with diagnostic ISCL scores whereas the 7 patients with either subdiagnostic ISCL scores or reactive histology showed no phenotypic abnormality by flow cytometry. In all, 10 of 11 patients with diagnostic skin biopsy specimens for MF had T-cell receptor gene rearrangements by polymerase chain reaction. Gene rearrangements were not detected in the subdiagnostic group.

LIMITATIONS

Small study size was a limitation.

CONCLUSION

Flow cytometry of skin biopsy specimens is a sensitive method for detecting abnormalities in MF and should be considered part of the routine workup of patients with a clinical suggestion of MF.

A novel method for interpretation of T-cell receptor gamma gene rearrangement assay by capillary gel electrophoresis based on normal distribution

T-cell receptor gamma (TRG) gene rearrangement status is useful for the differential diagnosis of T-cell lesions. The BIOMED-2 protocol that uses two sets of Jgamma and four sets of Vgamma primers in a multiplex, two-tube reaction followed by capillary gel electrophoresis is emerging as a standard assay for this application. Here, we report a computer-aided method to evaluate the significance of a peak in this TRG clonality assay. A best-fit normal distribution (ND) curve and the chi(2) error for each peak are used to determine whether a peak is significantly taller than the background (cutoff for Vgamma(1-8) is 1). Eighty clinical samples that have been previously analyzed by a GC-clamped primer polymerase chain reaction/denaturing gradient gel electrophoresis assay were reanalyzed with the BIOMED-2 assay and scored by the ND method and four previously published methods: relative peak height (RPH), relative peak ratio (RPR), height ratio (HR), and peak height ratio (Rn). A greater than 90% concordance rate was observed between RPH and ND analysis, whereas RPR, Rn, and HR had a lower threshold to call a peak positive. The advantage of the ND method is that it is more objective, reproducible, and can be automated.

Primary Cutaneous Lymphoproliferative Disorders With Dual Lineage Rearrangement

We present a series of 15 cases of cutaneous lymphoma and pseudolymphoma with dual lineage rearrangement identified among approximately 1200 cases of cutaneous lymphoproliferative disorders assessed in our 4 institutions during the last 8 years in which the results of both T-cell receptor and immunoglobulin heavy chain rearrangement investigations were available. On the basis of the clinicopathologic information, the cases were retrospectively subdivided into 2 categories: (1) cases with definite features of cutaneous lymphoma or pseudolymphoma (n = 11) and (2) cases with unclassifiable disease (n = 4). The detection of dual genotype in the first group did not influence the final diagnosis; 7 cases represented cutaneous B-cell lymphomas, 3 pseudolymphomas, and 1 case lymphomatoid papulosis. The presence of monoclonal T-cell receptor-gene rearrangements in these cases may be explained either by monoclonal or oligoclonal expansion of exuberant T cells (or B cells in case of lymphomatoid papulosis) or by lineage infidelity. Three patients with unclassifiable disease had several clinical and histopathologic features in common. They were elderly, presented with solitary lesions, were in good general health and histopathologically demonstrated a dense multinodular infiltrate containing approximately an equal number of T and B cells and a high number of histiocytes forming granulomas, with prominent granulomatous features in 2 cases. B cells were either scattered with the infiltrate or formed collections vaguely resembling follicles; Reed-Sternberg-like cells were seen in 2 cases. B cells showed expression neither of immunoglobulin light chain. The T-cell component was represented mainly by small, well-differentiated lymphocytes or slightly pleomorphic cells, with some medium-sized convoluted cells. Epstein-Barr virus was not detected by polymerase chain reaction. The exact classification of these cases is unknown; they differ histopathologically from previously published cases of bigenotypic cutaneous lymphomas. They may merely represent a growth or reactive pattern, but, on the other hand, may be low-grade lymphomas. If so, they may be histopathologically related to cutaneous Hodgkin disease, T-cell/histiocyte-rich large B-cell lymphoma, or composite lymphomas. Further reports are needed to identify these lesions to clarify their nature and biologic potential.

[Mycosis fungoides-type eruptions induced by carbamazepine]

Cutaneous pseudolymphomas are inflammatory diseases of the skin that simulate malignant lymphomas in their clinical and/or histological form. Those induced by drugs are infrequent and are characterized by their clinical and histological polymorphism. There is no consensus regarding the definition of these dermatoses, and they can be seen in different forms of presentation. There are two main groups of drug-induced pseudolymphomas: those that clinically and histologically simulate cutaneous lymphomas, and those known as hypersensitivity syndromes. Pseudolymphomas cannot be differentiated from true lymphomas through clinical, pathological or molecular findings. The definitive test for diagnosis is the resolution of the lesions after the medication involved is suspended. We present three cases of carbamazepine-induced cases of pseudolymphomas that histologically simulate mycosis fungoides, with different clinical presentations.

On the diagnosis of erythrodermic cutaneous T-cell lymphoma

Erythrodermic cutaneous T-cell lymphoma (E-CTCL) is the cause of less than 5% of all cases of generalized erythroderma. A methodical evaluation of skin, blood, and lymph node samples using standard histology, immunohistochemistry (IHC), flow cytometry (FC), and molecular analysis for evidence of a dominant T-cell clone has been recommended in a recently published diagnostic algorithm. In this commentary, the author discusses available information regarding the role of these diagnostic methods for the diagnosis of E-CTCL with emphasis on personal observations regarding skin IHC and polymerase chain reaction (PCR)-based molecular studies as adjunct diagnostic studies on a series of 55 patients with erythrodermic mycosis fungoides and 50 patients with Sézary syndrome compared to 50 patients with extensive benign inflammatory skin disease. The conclusions are (1) IHC of the skin does not reliably differentiate E-CTCL from benign simulants, (2) presence of phenotypically abnormal T cells in the blood or expanded subsets of CD4+CD7- or CD4+CD26- cells by FC is particularly helpful as a diagnostic study, (3) the presence of an identical T-cell clone in the skin and blood also is a specific diagnostic criterion for E-CTCL, but exceptions may occur, and (4) the PCRgamma-denaturing gradient gel electrophoresis technique appears to be more reliable than PCRgamma-single-stranded conformational polymorphism for diagnostic purposes.

Assessment of T-cell Clonality via T-cell Receptor-γ Rearrangements in Cutaneous T-cell–Dominant Infiltrates Using Polymerase Chain Reaction and Single-stranded DNA Conformational Polymorphism Assay

Discerning the pathologic significance of cutaneous T-cell infiltrates can pose a diagnostic challenge for dermatopathologists. Reactive conditions such as drug-associated lymphomatoid hypersensitivity and lymphomatoid lupus erythematosus can demonstrate lymphoid atypia and a phenotype resembling cutaneous T-cell lymphoma (CTCL). Further, lymphoid dyscrasias such as pityriasis lichenoides chronica, large plaque parapsoriasis, and atypical pigmentary purpura confuse the picture because they not only mimic CTCL but also represent prelymphomatous states with inherent malignant potential. Although the emergence of a dominant clone has been considered a clue indicative of a T-cell dyscrasia, there are reports concerning the identification of monoclonality in biopsies of reactive lymphoid infiltrates. We have conducted a modified single-stranded DNA conformational polymorphism (SSCP) assay using paraffin-embedded, formalin-fixed tissue on 92 T-cell-rich biopsies to determine the relative specificity and sensitivity of this methodology. In addition, laser capture microdissection (LCM) was performed on 22 of the 92 samples to isolate the area of interest and to compare its specificity and sensitivity with those SSCP assays performed without LCM. We found that monoclonality or oligoclonality is 86% specific for preneoplastic and neoplastic states, whereas the finding of polyclonality appears to be relatively specific for a reactive process. Some cases of reversible T-cell dyscrasia produced a molecular profile mimicking lymphoma or prelymphomatous states by virtue of monoclonality or oligoclonality. Although LCM appears to improve the sensitivity for detecting preneoplastic conditions, the relative specificity appears to be the same as that encountered with routine SSCP.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

The utility of the in situ detection of T-cell receptor Beta rearrangements in cutaneous T-cell-dominant infiltrates

The diagnostic assessment of cutaneous T-cell infiltrates is problematic for dermatopathologists. A variety of conditions, including lymphomatoid hypersensitivity reactions and lymphomatoid lupus erythematosus, can demonstrate lymphoid atypia and phenotypic changes that can mimic cutaneous T-cell lymphoma (CTCL). A similar issue revolves around lymphoid dyscrasias, which includes parapsoriasis, atypical pigmentary purpura, pityriasis lichenoides chronica, indeterminate lymphocytic lobular panniculitis, and lymphomatoid papulosis, which can progress to CTCL. A reverse transcription (RT) in situ PCR assay for T-cell receptor beta rearrangements (TCRbeta) was used to assess T-cell clonality in formalin-fixed, paraffin-embedded tissues. In 7 of 8 cases of classic CTCL, the RT in situ PCR assay for TCRbeta rearrangement showed monoclonality; the other was biclonal. Further, in cases with multiple lesions over time, the same T-cell clone could be detected including in those patients whose biopsies showed large-cell transformation. Monoclonality was also demonstrated in each of 2 cases of cutaneous lymphomatoid papulosis. Demonstration of oligoclonality (and one case of biclonality) by RT in situ PCR was confined to those cases that either represented prelymphomatous conditions such as large plaque parapsoriasis or pityriasis lichenoides or lesions of drug-induced lymphomatoid hypersensitivity that all demonstrated clinical regression. In conclusion, RT in situ PCR for TCRbeta, which can be done on formalin-fixed biopsies and allows direct correlation of the molecular data with the histology, is a useful adjunctive test in the differentiation of CTCL from its mimics.

Lymphomatoid drug eruption mimicking digitate dermatosis: cross reactivity between two drugs that suppress angiotensin II function

A 75-year-old male presented with an eruption characteristic of digitate dermatosis. The eruption cleared completely after discontinuation of lisinopril (angiotensin converting enzyme inhibitor). Eighteen months later a similar eruption recurred after using valsartan (a competitive inhibitor of angiotensin II receptor). The eruption cleared after discontinuation of valsartan. Histologic findings in both eruptions were consistent with lymphomatoid drug eruption. This case is interesting in that the eruption occurred after the intake of two structurally unrelated drugs that interfere with angiotensin II function. This observation may shed light on the mechanisms that may be operative in provoking the lymphomatoid drug eruption.

Cutaneous lymphoid hyperplasia: a lymphoproliferative continuum with lymphomatous potential

Cutaneous lymphoid hyperplasia (CLH) has been proposed to be the benign end of a continuum of lymphoproliferative disorders with cutaneous lymphoma at its malignant extreme. An intermediate condition, known as "clonal CLH," was first recognized by us and shown to be a transitional state capable of eventuating in overt lymphoma. To better determine the prevalence of dominant clonality and risk of lymphoma among CLH cases, we studied the immunohistology and clonality of fresh-frozen samples from 44 CLH patients referred to a multidisciplinary cutaneous lymphoproliferative disorders program. Using a large panel of lymphoid markers, the cases were divided into 38 typical mixed B-cell/T-cell type CLH and 6 T-cell-rich type (T-CLH), the latter containing > 90% T cells. Of the 44 patients, 38 had solitary or localized lesions (4 cases of T-CLH), and 6 had regional/generalized lesions (2 cases of T-CLH). Forty cases were of idiopathic etiology. Suspected etiologies among 4 other cases included mercuric tattoo pigment, doxepin, clozapine, and bacterial infection. Immunoglobulin heavy chain (IgH) and T-cell receptor (TCR)-gamma gene rearrangements (GR) were studied using polymerase chain reaction assays, which are approximately 80% sensitive. Overall, 27 cases (61%) showed clonal CLH: 12 IgH+ (27%; 3 cases of T-CLH); 13 TCR+ (30%; 1 case of T-CLH); and 2 IgH+/TCR+ (4%; neither case was T-CLH). Two cases (4%; 1 case of T-CLH) progressed to cutaneous B-cell lymphoma. Both of these patients presented with regional lesions. Our findings indicate that clonal overgrowth is common in CLH, links CLH to lymphoma, and probably involves both B- and T-cell lineages (although TCR GR by B cells and vice versa could not be ruled out). The high prevalence of dominant clonality in our series may have resulted from the sensitivity of our PCR assays as well as patient selection.

Clinicopathological and genotypic aspects of anticonvulsant-induced pseudolymphoma syndrome

BACKGROUND

Pseudolymphoma syndrome (PLS) is relatively rare but can lead to death if there are extensive skin lesions, severe hepatitis, agranulocytosis and neutropenia. PLS may also give rise to harmful effects if misdiagnosed as malignant lymphoma and patients with PLS are treated unnecessarily with chemotherapy, because it may mimic histologically other lymphomas, including mycosis fungoides (MF).

OBJECTIVES

To examine the clinicopathological and genotypic features of anticonvulsant-induced PLS. Patients and methods We retrospectively reviewed clinical, laboratory and histological findings for eight cases of anticonvulsant-induced PLS, and performed T-cell receptor gene rearrangement using polymerase chain reaction with paraffin-embedded specimens from each case.

RESULTS

The causative agents were carbamazepine (four cases), phenytoin (two cases), phenobarbital (one case) and valproic acid (one case). A cross-reaction between phenobarbital and phenytoin was observed in one case. The duration from the start of anticonvulsant therapy to skin eruption was 3-24 weeks (mean 7 weeks). The skin lesions were generalized maculopapular eruptions in all cases, including one case accompanied by vesiculopustular lesions. The frequencies of the associated features were as follows: facial oedema (88%), fever (75%), lymphadenopathy (63%), and hepatomegaly (25%). Laboratory findings revealed leukocytosis, atypical lymphocytes, eosinophilia, monocytosis, neutrophilia, lymphocytosis and abnormal liver function. Histopathologically, there was similarity between PLS and MF in that epidermotrophism of atypical lymphocytes (100%) and Pautrier's microabscess-like structures (38%) were observed. However, PLS has some differences from MF that include moderate to marked spongiosis (75%), necrotic keratinocytes (63%), and infiltration of eosinophils (25%) in the epidermis and, in the dermis, papillary dermal oedema (100%), extravasated erythrocytes (100%), lymphocytes within the dermis larger than those within the epidermis (63%), and infiltration of various inflammatory cells including neutrophils (50%). Genotypic analysis demonstrated a rearrangement of the T-cell receptor-gamma gene in one of eight cases studied. There were no deaths and all cases were improved at 2-9 weeks (mean 6 weeks), after the cessation of causative agents, systemic and topical corticosteroid therapy, and symptomatic therapy. There were no significant differences in clinical, laboratory and histological findings between the causative agents.

CONCLUSIONS

PLS may show histopathological findings similar to MF and take a prolonged course even after the cessation of causative agents. Thus, a clear understanding and diagnosis of this disease is considered to have an important effect on treatment and prognosis.

Drug-induced reversible lymphoid dyscrasia: a clonal lymphomatoid dermatitis of memory and activated T cells

Certain systemic conditions predispose patients to excessive lymphocyte responses to immune-perturbing drugs, which may progress to malignant lymphoma. Many pathologists and clinicians believe that differentiation of pseudolymphoma from cutaneous T cell lymphoma (CTCL) can be reliably made through phenotypic and molecular analysis. We encountered 15 cases of atypical cutaneous T-cell lymphoid hyperplasia in the setting of drug therapy. We explored phenotypic anomalies using antibodies to CD2, 3, 4, 7, 8, 20, 30 and CD62 K and sought T-cell receptor gene rearrangements by a polymerase chain reaction methodology. The lymphoid infiltrates showed reproducible CD7 and/or CD62 K deletion in concert with T cell clonality and variable CD30 positivity-findings similar to those of CTCL-but the rashes resolved or improved substantially after drug modulation. We hypothesize that the infiltrates represent an unrepressed expansion of CD7- and CD62 K-negative activated memory T lymphocytes in response to antigenic triggers. We propose the term "drug-induced reversible lymphoid dyscrasia" to describe this entity.

The value of molecular analysis by PCR in the diagnosis of cutaneous lymphocytic infiltrates

The diagnosis and classification of cutaneous lymphomas remain a challenge for the clinician and dermatopathologist. This diagnostic dilemma is mainly encountered in the distinction between an early malignant lymphoma and a benign reactive lymphocytic infiltrate (pseudolymphoma). Until the beginning of the 1980s, our diagnostic tools were limited to the clinical presentation, course, and histopathology in diagnosis and classification of lymphocytic infiltrates. Advances in immunology and, in particular, in molecular genetics with the introduction of the Southern blot technique and the polymerase chain reaction (PCR) have revolutionized the diagnosis of lymphocytic infiltrates by determination of clonality. In some series, more than 90% of cutaneous T-cell lymphomas have a clonal rearrangement of the T-cell receptor gamma-chain gene, as opposed to very low percentages of rearrangement in T-cell pseudolymphomas. However, the presence of clonality does not necessarily imply malignancy. Cases of pseudolymphomas, lichen planus and pityriasis lichenoides et varioliformis acuta were reported with clonal lymphocytic proliferations. Therefore, care should be exercised in the evaluation of the results of molecular analysis, and these should always be correlated with the clinical, histological and immunophenotypic picture to arrive at the correct diagnosis. It may be expected that the molecular methods for diagnosis of lymphocytic infiltrates will be improved and refined in future, and that sensitivity and specificity will increase.

Pityriasis lichenoides: a clonal T-cell lymphoproliferative disorder

Pityriasis lichenoides (PL) is a papulosquamous disorder often considered a form of reactive dermatosis and classified with small plaque parapsoriasis (digitate dermatosis). However, some patients with PL have developed large plaque parapsoriasis (LPP) and mycosis fungoides (MF), and lymphoid atypia and T-cell clonality have been reported in lesions of PL. We set out to explore the possibility that PL is a form of T-cell dyscrasia. Cases were selected by natural language search from an outpatient dermatopathology database; 35 cases were reviewed and clinicians and patients were contacted. Hematoxylin and eosin-stained sections were examined and immunophenotyping was carried out on paraffin-embedded, formalin-fixed tissue using antibodies to CD2, CD3, CD4, CD5, CD7, CD8, CD20, CD30, and CD56. In paraffin-embedded tissue, T-cell receptor (TCR)-gamma chain rearrangement was sought through polymerase chain reaction single stranded conformational polymorphism analysis. There were 14 males and 21 females with a mean age of 40 years held clinically to have PL chronica (PLC) (28 cases) and/or PL et varioliformis acuta (PLEVA) (7 cases). Five patients developed large atrophic poikilodermatous and/or annular plaques compatible with MF and/or LPP in a background of typical PLC. All biopsies showed tropism of lymphocytes to an epidermis manifesting psoriasiform hyperplasia, dyskeratosis, parakeratosis, and intraepithelial collections of Langerhans' cells and lymphocytes mimicking Pautrier's microabascesses. Epidermal atrophy, dermal fibroplasia, poikilodermatous alterations, and a dominance of intraepidermal cerebriform cells were seen only in patients with chronic persistent disease (i.e., PLC) and in some cases corresponded with clinical progression to MF. All cases had a T cell-dominant infiltrate, with a CD7 deletion in 21 of 32 biopsies examined; the CD7-negative cells were typically the largest and most atypical forms, often in a cohesive array within the upper layers of the epidermis. In 17 biopsies in which a CD4 stain was satisfactory for evaluation, 50% or more of the intraepidermal population was CD4 positive in 8 biopsies, whereas in 11 biopsies 50% or more of the dermal infiltrate was CD4 positive. The CD4-positive cells frequently had a cerebriform nuclear morphology and were CD7 negative. Most cases had an admixture of CD8-positive lymphocytes in excess of 40% or more of the intraepidermal and/or dermal infiltrate; it was the dominant intraepidermal infiltrate in 10 cases. The CD8-positive cells, typically small, round, and CD7 positive, showed a directed pattern of migration into acrosyringia and suprapapillary plates, with satellitosis around CD4-positive/CD8-negative/CD7-negative atypical lymphocytes. CD56 positivity was seen among the intraepidermal lymphoid cells and roughly paralleled the CD8 profile. In general, CD8-positive lymphocytes dominated in cases of PLEVA, whereas CD4-positive lymphocytes were very conspicuous and composed the dominant intraepidermal populace only in those biopsies of progressive PL/PLC. Clonality was shown in 25 of 27 biopsies in which amplifiable DNA was obtained. Intraepithelial atypical lymphocytes, phenotypic abnormalities, and TCR-gamma rearrangements suggest that PLC and PLEVA are a form of T-cell dyscrasia. Lesions may follow a recalcitrant course characteristic of MF and premycotic disorders such as LPP. The aberrant phenotype cell is similar to that defining MF: a CD4-positive T lymphocyte with a CD5 and CD7 deletion. Directed epidermal migration seen in biopsies procured from incipient lesions along with occasional temporal association to viral or drug exposure suggests that an abnormal immune response to an antigenic trigger may be the inciting event.

Cutaneous lymphomas: which pathological classification?

Cutaneous lymphomas are rare and although some are a manifestation of systemic lymphoma, the majority arise primarily from the skin. These primary cutaneous lymphomas comprise predominantly T cell subtypes and represent a wide spectrum of disorders. Pathologists can currently choose to label these conditions according to three classifications (REAL, EORTC or WHO) but each has shortcomings. Nonetheless, in an attempt to unify the field, we would recommend that pathologists make every attempt to categorise these conditions according to the WHO classification. This classification can encompass all the conditions and aligns the cutaneous lymphomas with the broader systemic lymphoproliferative conditions.

Germline RET 634 mutation positive MEN 2A-related C-cell hyperplasias have genetic features consistent with intraepithelial neoplasia

C-cell hyperplasias are normally multifocal in multiple endocrine neoplasia type 2A. We compared clonality, microsatellite pattern of tumor suppressor genes, and cellular kinetics of C-cell hyperplasia foci in each thyroid lobe. We selected 11 females from multiple endocrine neoplasia type 2A kindred treated with thyroidectomy due to hypercalcitoninemia. C-cell hyperplasia foci were microdissected for DNA extraction to analyze the methylation pattern of androgen receptor alleles and microsatellite regions (TP53, RB1, WT1, and NF1). Consecutive sections were selected for MIB-1, pRB1, p53, Mdm-2, and p21WAF1 immunostaining, DNA content analysis, and in situ end labeling. Appropriate tissue controls were run. Only two patients had medullary thyroid carcinoma foci. Nine informative C-cell hyperplasia patients showed germline point mutation in RET, eight of them with the same androgen receptor allele preferentially methylated in both lobes. C-cell hyperplasia foci showed heterogeneous DNA deletions revealed by loss of heterozygosity of TP53 (12 of 20), RB1 (6 of 14), and WT1 (4 of 20) and hypodiploid G0/G1 cells (14 of 20), low cellular turnover (MIB-1 index 4.5%, in situ end labeling index 0.03%), and significantly high nuclear area to DNA index ratio. MEN 2A (germline point mutation in RET codon 634) C-cell hyperplasias are monoclonal and genetically heterogeneous and show down-regulated apoptosis, findings consistent with an intraepithelial neoplasia. Concordant X-chromosome inactivation and interstitial gene deletions suggest clone expansions of precursors occurring at a point in embryonic development before divergence of each thyroid lobe and may represent a paradigm for other germline mutations.

Sodium valproate-induced cutaneous pseudolymphoma followed by recurrence with carbamazepine

We report a patient with a sodium valproate-induced cutaneous pseudolymphoma, presenting with an erythematous papule, histologically mimicking a non-epidermotropic T-cell lymphoma. Polymerase chain reaction study of the skin biopsy revealed monoclonal rearrangement of the T-cell receptor gamma gene. Withdrawal of sodium valproate was followed by regression of the lesion, but 5 months after substitution by carbamazepine, two further papules appeared, with similar histological features and a T-cell clone identical to the initial one. Carbamazepine was stopped and the lesions disappeared without relapse over a 4-year follow-up. Sodium valproate is very rarely responsible for a hypersensitivity syndrome, and our case is the first report of sodium valproate-induced cutaneous pseudolymphoma. The recurrence with carbamazepine may be due to a common effect on T-cell lymphocyte function. The return of the same monoclonal population shows that the recurrence of monoclonal T cells may be observed in benign conditions and is not an exclusive hallmark of cutaneous lymphoma.

PCR techniques for clonality assays

Clonal overgrowths represent the hallmark of neoplastic proliferations, and their demonstration has been proved useful clinically for the diagnosis of malignant lymphomas based on the detection of specific and dominant immunoglobulin and/or T-cell receptor gene rearrangements. Nonrandom genetic alterations can also be used to test clonal expansions and the clonal evolution of neoplasms, especially analyzing hypervariable deoxyribonucleic acid (DNA) regions from patients heterozygous for a given marker. These tests rely basically on the demonstration of loss of heterozygosity (LOH) resulting from either hemizygosity (nonrandom interstitial DNA deletions) or homozygosity of mutant alleles observed in neoplasms. LOH analyses identify clonal expansions of a tumor cell population, and point to monoclonal proliferation when multiple and consistent LOH are demonstrated. Based on the methylation-related inactivation of one X chromosome in female subjects, X-linked markers (e.g., androgen receptor gene) will provide clonality information using LOH analyses after DNA digestion with methylation-sensitive restriction endonucleases. Therefore, both non-X-linked and X-linked analyses give complementary information, related and not related to the malignant transformation pathway respectively. Applied appropriately, these tools can establish the clonal evolution of tumor cell populations (tumor heterogeneity), identify early relapses, distinguish recurrent tumors from other metachronic neoplasms, and differentiate field transformation from metastatic tumor growths in synchronic and histologically identical neoplasms.

An approach to the sensitivity of temperature-gradient gel electrophoresis in the detection of clonally expanded T-cells in cutaneous T-cell lymphoma

Detection of T-cell clonality by polymerase chain reaction (PCR) and high-resolution electrophoresis facilitates differentiation of early stages of cutaneous T-cell lymphoma (CTCL) from benign T-cell-rich dermatoses. However, data regarding the sensitivity of the various electrophoresis techniques differ remarkably. In the present study, the capacity of heteroduplex (HD)-loaded temperature-gradient gel electrophoresis (TGGE) to detect clonally expanded T-cells was assessed systematically and modifications to the procedure were defined. Using our standard protocol, HD-TGGE detected clonal T-cell receptor (TCR)-gamma PCR products, generated from the Jurkat cell line, down to a total of 2 ng/microL (14 ng) DNA. However, slowly migrating single strands of the clonal PCR product reduced the amount of the clonality indicating homoduplices. To overcome this single-strand formation, thus decreasing the detection limit, the urea concentration in the gel and the temperature ramp for the HD-formation were altered, as well as the temperature gradient in the gel. Application of the modified protocol resulted in a tenfold lower detection limit of 0.15 ng/microL (1.05 ng) DNA in the clonal band. The sensitivity of the adapted HD-TGGE was investigated by dilution experiments using the well established T-cell lines Jurkat, Molt-4, MyLa and SeAx. By these approaches clonal PCR products diluted in nonclonal PCR products were detectable down to concentrations of 5-10%. Comparably, in the case of mixtures of clonal in nonclonal DNA the detection limit reached 5-10% clonal DNA. However, by dilution of clonal cells in nonclonal peripheral blood mononuclear cells, which corresponds to in vivo conditions, a lower detection limit of approximately 1-5% was observed.

Diagnostic value of dominant T-cell clones in peripheral blood in 363 patients presenting consecutively with a clinical suspicion of cutaneous lymphoma

It is now widely accepted that polymerase chain reaction (PCR) analysis of cutaneous T-cell clonality is of diagnostic value in cutaneous T-cell lymphomas (CTCLs) and most helpful in the diagnosis of mycosis fungoides (MF). However, the diagnostic and prognostic value of circulating clonal T cells remains unclear. We studied T-cell clonality in the peripheral blood (PB) and the cutaneous lesion, sampled at the same time, in 363 consecutively seen patients with a clinical suspicion of cutaneous lymphoma. Using a PCR technique providing a specific imprint of T-cell clones (PCRγ–denaturing gradient gel electrophoresis), we found that detection of identical circulating and cutaneous T-cell clones was associated with the diagnosis of CTCL (P < .001). Detection of circulating tumor cells in patients with MF was infrequent (12.5%), except in those with erythrodermic MF (42%; P = .003). Moreover, among the 46 patients who had identical circulating and cutaneous T-cell clones, 25 (56%) had erythroderma. The finding of a dominant clone in the PB but not in the skin was frequent, regardless of the clinicohistologic classification; it occurred in 30% of patients with CTCL, 41% with non-CTCL malignant infiltrates, and 34% with benign infiltrates. This pattern was significantly more frequent in patients over 60 years of age (P < .002), even in the CTCL group (P < .01). In conclusion, dominant T-cell clones detected in the PB of patients with MF by using a routine PCR technique are rarely tumoral and are more often related to age. A multicenter prospective study is under way to establish the prognostic value of circulating tumor cells.

Diagnostic value of dominant T-cell clones in peripheral blood in 363 patients presenting consecutively with a clinical suspicion of cutaneous lymphoma

It is now widely accepted that polymerase chain reaction (PCR) analysis of cutaneous T-cell clonality is of diagnostic value in cutaneous T-cell lymphomas (CTCLs) and most helpful in the diagnosis of mycosis fungoides (MF). However, the diagnostic and prognostic value of circulating clonal T cells remains unclear. We studied T-cell clonality in the peripheral blood (PB) and the cutaneous lesion, sampled at the same time, in 363 consecutively seen patients with a clinical suspicion of cutaneous lymphoma. Using a PCR technique providing a specific imprint of T-cell clones (PCRγ–denaturing gradient gel electrophoresis), we found that detection of identical circulating and cutaneous T-cell clones was associated with the diagnosis of CTCL (P < .001). Detection of circulating tumor cells in patients with MF was infrequent (12.5%), except in those with erythrodermic MF (42%; P = .003). Moreover, among the 46 patients who had identical circulating and cutaneous T-cell clones, 25 (56%) had erythroderma. The finding of a dominant clone in the PB but not in the skin was frequent, regardless of the clinicohistologic classification; it occurred in 30% of patients with CTCL, 41% with non-CTCL malignant infiltrates, and 34% with benign infiltrates. This pattern was significantly more frequent in patients over 60 years of age (P < .002), even in the CTCL group (P < .01). In conclusion, dominant T-cell clones detected in the PB of patients with MF by using a routine PCR technique are rarely tumoral and are more often related to age. A multicenter prospective study is under way to establish the prognostic value of circulating tumor cells.

Clonal patterns in phaeochromocytomas and MEN-2A adrenal medullary hyperplasias: histological and kinetic correlates

The relationship among histological features, cell kinetics, and clonality has not been studied in adrenal medullary hyperplasias (AMHs) and phaeochromocytomas (PCCs). Thirty-four PCCs (23 sporadic and 11 MEN-2A (multiple endocrine neoplasia type 2A)-related tumours, the latter associated with AMH) from females were included in this study. Representative samples were histologically evaluated and microdissected to extract DNA and evaluate the methylation pattern of the androgen receptor alleles. At least two tissue samples (from the peripheral and internal zones in each tumour) were analysed with appropriate tissue controls run in every case. The same areas were selected for MIB-1 staining and in situ end labelling (ISEL). Malignant PCCs were defined by histologically confirmed distant metastases. All monoclonal AMH nodules from the same patient showed the same X-chromosome inactivated. Six sporadic PCCs revealed liver metastases (malignant PCC) and eight additional sporadic PCCs showed periadrenal infiltration (locally invasive PCC). All informative PCCs were monoclonal, except for five locally invasive PCCs and one benign PCC that revealed polyclonal patterns. Those cases also showed a fibroblastic stromal reaction with prominent blood vessels, focal smooth muscle differentiation, and significantly higher MIB-1 (126.8+/-29.9) and ISEL (50.9+/-12.8) indices. Concordant X-chromosome inactivation in nodules from a given patient suggests that MEN-2A AMH is a multifocal monoclonal condition. A subgroup of PCCs characterized by balanced methylation of androgen receptor alleles, high cellular turnover, and stromal proliferation also shows locally invasive features.

Primary cutaneous T-cell lymphoma: review and current concepts

PURPOSE

Primary cutaneous T-cell lymphomas (CTCLs) encompass a wide variety of lymphomas that are characterized by the localization of the malignant lymphocytes to the skin at presentation. Advances in molecular biologic techniques, including immunophenotyping and gene rearrangement studies to determine clonality, have led to more frequent diagnosis of CTCL as well as more consistent subclassification of these entities. However, there continues to be confusion in the classification, prognosis, and management of patients with CTCL. The purpose of this review is to present a summary of the diagnosis, prognosis, and treatment of CTCL, with specific emphasis on mycosis fungoides (MF) and Sézary syndrome (SS). We also present a detailed discussion of the entities that make up the differential diagnosis of CTCL.

DESIGN

We reviewed the medical literature on CTCL and other diseases that make up the differential diagnosis of CTCL.

RESULTS AND CONCLUSION

MF and SS are the most common forms of CTCL. The etiology of this disease is still unknown. Patients may go for months to years with skin abnormalities before being diagnosed. MF/SS is an indolent disease and patients with T1 disease have a normal life expectancy. Patients who undergo transformation to large-cell lymphoma (8% to 23% of patients) have a poor prognosis, with mean survival ranging from 2 to 19 months. Treatment for MF/SS continues to be palliative. There are many new therapies that are currently being investigated in clinical trials, and the DAB(389)IL-2 fusion protein was recently approved for the treatment of refractory MF/SS.

Cutaneous lymphoid hyperplasias

Benign hyperplastic lymphoid infiltrates of the skin (pseudolymphoma, older term) simulate lymphoma clinically and histologically. They can be divided into B-cell predominant (typical cutaneous lymphoid hyperplasia (CLH), angiolymphoid hyperplasia, Kimura's disease, and Castleman's disease) and T-cell predominant (T-cell CLH, lymphomatoid contact dermatitis, and lymphomatoid drug eruption). Both types may represent exaggerated reactions to diverse external antigens (insect bite, tattoo, zoster, trauma, among others). A composite assessment of clinical presentation and behavior, routine histology, immunophenotyping, and molecular studies is essential for the diagnosis of benign cutaneous lymphoid infiltrates. Treatment includes antibiotics, intralesional and systemic corticosteroids, excision, radiotherapy, and immunosuppressants. Treatment depends on the assessment and biologic behavior, which is usually benign. Molecular biologic analysis has shown that a significant proportion of cases harbor occult B- or T-cell clones (clonal CLH). Progression to overt cutaneous lymphoma has been observed in a minority of cases. Patients with clonal populations of B or T cells and persistent lesions should be closely observed for emergence of a lymphoma.