Cytotoxic/natural killer cell cutaneous lymphomas. Report of EORTC Cutaneous Lymphoma Task Force Workshop

Cutaneous Intravascular Hematolymphoid Entities: A Review

Intravascular lymphomas are rare disease conditions that exhibit neoplastic lymphoid cells that are confined mainly to the lumens of small capillaries and medium-sized vessels. The majority of the intravascular lymphomas are of B-cell origin, but they can include NK/T-cell and CD30+ immunophenotypes. In the histologic differential diagnosis are benign proliferations such as intralymphatic histiocytosis and intravascular atypical CD30+ T-cell proliferation. In this review, we discuss the clinical, histopathologic, and molecular findings of intravascular B-cell lymphoma, intravascular NK/T-cell lymphoma, intralymphatic histiocytosis, and benign atypical intravascular CD30+ T-cell proliferation.

Intravascular NK/T-cell lymphoma: a case report and literature review

Intravascular lymphoma is characterized by an exclusively intravascular distribution of tumor cells. Intravascular natural killer/T-cell lymphoma (IVNKTL) is extremely rare, highly aggressive, commonly Epstein-Barr virus (EBV)-positive, and predominantly affects the skin and central nervous system. Here we report a case of IVNKTL diagnosed in a 67-year-old female, presenting with persistent intermittent fever and skin rashes throughout the body. Incisional biopsy of an erythematous lesion on the chest exhibited aggregation of medium to large-sized atypical lymphoid cells confined to the lumen of small vessels that were positive for CD3, granzyme B, and CD56 on immunohistochemistry and EBV-encoded RNA in situ hybridization. EBV DNA was also detected in serum after diagnosis. With a review of 26 cases of IVNKTL to date, we suggest that active biopsy based on EBV DNA detection may facilitate early diagnosis of IVNKTL.

Primary Cutaneous Multifocal Indolent CD8+ T-Cell Lymphoma: A Novel Primary Cutaneous CD8+ T-Cell Lymphoma

We report the case of a patient who was referred to our institution with a diagnosis of CD4+ small/medium-sized pleomorphic lymphoma. At the time, the patient showed a plethora of lesions mainly localizing to the legs; thus, we undertook studies to investigate the lineage and immunophenotype of the neoplastic clone. Immunohistochemistry (IHC) showed marked CD4 and CD8 positivity. Flow cytometry (FCM) showed two distinct T-cell populations, CD4+ and CD8+ (+/- PD1), with no CD4/CD8 co-expression and no loss of panT-cell markers in either T-cell subset. FCM, accompanied by cell-sorting (CS), permitted the physical separation of four populations, as follows: CD4+/PD1-, CD4+/PD1+, CD8+/PD1- and CD8+/PD1+. TCR gene rearrangement studies on each of the four populations (by next generation sequencing, NGS) showed that the neoplastic population was of T-cytotoxic cell lineage. IHC showed the CD8+ population to be TIA-1+, but perforin- and granzyme-negative. Moreover, histiocytic markers did not render the peculiar staining pattern, which is characteristic of acral CD8+ T-cell lymphoma (PCACD8). Compared to the entities described in the 2018 update of the WHO-EORTC classification for primary cutaneous lymphomas, we found that the indolent lymphoma described herein differed from all of them. We submit that this case represents a hitherto-undescribed type of CTCL.

Intravascular NK/T-Cell Lymphoma: What We Know about This Diagnostically Challenging, Aggressive Disease

Intravascular lymphoma is a form of lymphoid malignancy characterized by neoplastic cells growing almost exclusively within the lumina of small- to medium-sized blood vessels. Most cases are of B-cell origin with rare cases of natural killer or T-cell lineage. Extranodal sites are affected, mainly the skin and central nervous system, although any organ may be involved. Intravascular NK/T-cell lymphoma deserves special attention because of its clinicopathologic features and the need for adequate immunophenotyping combined with clonality test for a proper diagnosis. Moreover, intravascular NK/T-cell lymphoma is strongly linked to Epstein-Barr virus (EBV), which is considered to play a role in tumorigenesis and to be responsible for the aggressive behavior of the disease. In this paper, we review the current knowledge on this rare lymphoma and, in particular, the most recent advances about its molecular landscape. The main distinguishing features with other EBV-related entities, such as extranodal NK/T-cell lymphoma, EBV-positive primary nodal T/NK-cell lymphoma, and aggressive NK-cell leukemia, are discussed to help pathologists obtain the correct diagnosis and consequently develop an adequate and prompt therapy response.

The Pathologic and Genetic Characteristics of Extranodal NK/T-Cell Lymphoma

Extranodal NK/T-cell lymphoma is a neoplasm of NK cells or cytotoxic T cells presenting in extranodal sites, most often in the nasal cavity. The typical immunophenotypes are cCD3+, sCD3-, CD4-, CD5-, CD8-, CD16-, and CD56+ with the expression of cytotoxic molecules. Tumor subsets express NK cell receptors, CD95/CD95L, CD30, MYC, and PDL1. Virtually all the tumor cells harbor the EBV genome, which plays a key role in lymphomagenesis as an epigenetic driver. EBV-encoded oncoproteins modulate the host-cell epigenetic machinery, reprogramming the viral and host epigenomes using host epigenetic modifiers. NGS analysis revealed the mutational landscape of ENKTL, predominantly involving the JAK-STAT pathway, epigenetic modifications, the RNA helicase family, the RAS/MAP kinase pathway, and tumor suppressors, which indicate an important role of these pathways and this group of genes in the lymphomagenesis of ENKTL. Recently, three molecular subtypes were proposed, the tumor-suppressor/immune-modulator (TSIM), MGA-BRDT (MB), and HDAC9-EP300-ARID1A (HEA) subtypes, and they are well-correlated with the cell of origin, EBV pattern, genomic alterations, and clinical outcomes. A future investigation into the function and interaction of discovered genes would be very helpful for better understanding the molecular pathogenesis of ENKTL and establishing better treatment strategies.

[Clinicopathological features of intravascular peripheral T-cell lymphoma]

Objective: To summarize the clinical and pathological features of intravascular NK and T cell lymphoma for better understanding of such disease to reduce misdiagnosis and miss-diagnosis. Methods: Clinical and pathological features were analyzed retrospectively in one case of intravascular peripheral T-cell lymphoma, not otherwise specified (IVPTCL, NOS) , with literatures review. Results: The case presented in this study was a 66-year-old man. PET/CT scan showed multiple lymph nodes enlargement throughout the body. Normal lymph node structure could not be observed by tissue biopsy, while lymph follicles were partially disrupted. High-power light microscope revealed a large number of blood vessels with diffuse proliferation and dilation, where atypical lymphoid cell mass was restricted in the lumen and partially infiltrated the large blood vessel wall. These tumor cells were medium to large with moderate cytoplasm. The nucleus was irregular, single or multiple nucleoli could be seen, chromatin was condensed, some were empty and bright, and mitotic figures could be seen. Immunohistochemical staining showed that the neoplastic cells were positive for expression of CD3, CD43, CD8, GrB, TIA-1 and perforin. EBER in situ hybridization result was negative. Polymerase chain reaction test identified a clonal gene rearrangement of T-cell receptor γ. The patient was treated with CHOP in combination with chidamide, but died of infection and cardiopulmonary failure within 2 months. 56 cases of intravascular NK/T cell lymphoma with definite classification were collected from relevant literatures, including 47 cases with nasal type of extranodal NK/T cell lymphoma (27 were male and 20 were female) , 8 cases with anaplastic large cell lymphoma (3 males and 5 females) , and only one case with de nova IVPTCL, NOS in brain. We report the second case of IVPTCL,NOS, and notably originated from lymph node for the first time. Conclusions: Intravascular NK/T cell lymphoma is a highly aggressive disease with no effective treatment at present. Involvement of Lymph node has rarely been reported, and further studies on more cases are necessary.

Intrapleural infections in patients with subcutaneous panniculitis-like T-cell lymphoma are susceptible to hemophagocytic lymphohistiocytosis

Patients with subcutaneous panniculitis-like T-cell lymphoma (SPTCL) are prone to the development of hemophagocytic lymphohistiocytosis (HLH). It is not known whether small infections in SPTCL patients can trigger the development of HLH. The clinical data were collected from 21 SPTCL patients admitted to our hospital from January 2006 to October 2019. Among 21 cases of SPTCL, six cases had HLH as the first manifestation (SPTCL/HLH), seven cases had intrathoracic infection (ITI), five cases were SPTCL/HLH, 13 cases had no ITI or HLH (SPTCL/no HLH). Two patients with SPTCL/noHLH healed spontaneously. We found that 28.6% of the SPTCL patients had HLH as the first presentation. ITI may cooperate with SPTCL to trigger HLH and a small number of SPTCL/noHLH can fully recover without treatment.

Gamma/Delta Phenotype in Primary Cutaneous T-cell Lymphomas and Lymphoid Proliferations: Challenges for Diagnosis and Classification

Primary cutaneous T-cell lymphomas pose a diagnostic challenge for dermatopathologists, hematopathologists, and general surgical pathologists. Recognition of gamma/delta phenotype in cutaneous T proliferations has been enhanced by the availability of antibodies against TCRgamma and delta for immunohistochemistry. Thus, reporting gamma/delta phenotype in a cutaneous T-cell lymphoid proliferation may indicate a significant change in therapy and a challenge for dermatologists and oncologists who treat these patients. Herein, we discuss primary cutaneous gamma/delta T-cell lymphoma, its differential diagnosis, and other skin lymphoid proliferations that may show gamma/delta phenotype. Awareness of the occurrence of gamma/delta phenotype in both T-cell lymphomas and benign lymphoid proliferations involving skin is crucial for a better interpretation of histopathologic findings. Integration of clinical presentation, morphology, immunoprofile, and molecular findings is key for a correct diagnosis and appropriate therapy of lesions displaying gamma/delta T-cell phenotype.

Extranodal NK/T-cell lymphoma, nasal type, with extranasal presentation - a case report and a review of the literature

BACKGROUND

Extranodal NK/T-cell lymphoma (ENKTCL), nasal type is a very rare and aggressive non-Hodgkin lymphoma. Most commonly it occurs in the upper aerodigestive tract. But, it can also manifest at locations such as the skin, soft tissue, gastrointestinal tract (GI), lungs, testis, etc. These locations are designated as extranasal ENKTCL. The patients with the latter have often more adverse clinical features and poorer survival rate compared with nasal sites. We present a case of an 83-year-old patient with a primary ENKTCL, nasal type, with extranasal presentation in the right upper eyelid.

MATERIAL AND METHODS

Materials for the literature review was obtained by a comprehensive search on PubMed, which yielded 82 eligible cases with extranasal ENKTCL.

RESULTS

Sixty-eight cases (83 %) were localized as primary ENKTCL in the lungs (17), central nervous system (CNS) (14), testis (11), GI-tract (7), skin (6), orbit and intraocular tissue (4), pancreas (2), adrenal gland (2), breast (1), etc. 14 cases (17 %) presented as extended or disseminated diseases involving exclusively organs outside the upper aerodigestive tract. There was no systematic pattern of organ involvement in the extended/disseminated ENKTCL. 63 % of the patient with localized extranasal ENKTCL and about 50% of patients with extended/disseminated disease were reported to have died of the disease. Treatment strategies varied with no preferred option. Among the used treatment options were chemotherapy, radiotherapy, surgery, stem cell transplantation alone or in different combinations.

CONCLUSION

ENKTCL is a highly aggressive disease which may present in extranasal areas. Although the tumors respond to both chemotherapy and radiotherapy, durable complete remissions are very rare.

Case of Extranodal Natural Killer/T-Cell Lymphoma, Nasal Type, Presenting With Intravascular Localization of Tumor Cells in Skin Biopsies From Both Plaque and Normal-Appearing Skin: A Case Report and Literature Review

Extranodal natural killer/T-cell lymphoma, nasal type (ENKTL-NT), is a rare subtype of non-Hodgkin lymphoma associated with Epstein-Barr virus. This type of lymphoma is rare in Western countries but is more frequent in East Asia and Latin America. ENKTL-NT mostly occurs in the nose and paranasal area, including the upper aerodigestive tract. The skin is the second-most commonly involved organ. ENKTL-ET is characterized by an angiocentric, angiodestructive pattern of growth with ulceration and necrosis evident on histopathological examination. We provide the first description of ENKTL-NT presenting with intravascular localization of tumor cells in skin biopsies from both plaque and normal-appearing skin. Random skin biopsy might thus be useful for early diagnosis, staging, and estimation of prognosis in ENKTL-NT. Moreover, the current case indicates that ENKTL-NT and intravascular natural killer/T-cell lymphoma may represent related diseases.

Cytogenetic complexity and heterogeneity in intravascular lymphoma

AIMS

To characterise the karyotypic abnormalities and heterogeneities in intravascular lymphoma (IVL).

METHODS

G-banded karyotyping was performed on biopsy specimens from a single-centre IVL cohort comprising intravascular large B-cell lymphoma (IVLBCL, n=12) and NK/T-cell lymphoma (IVNKTCL, n=1).

RESULTS

Five IVLBCL cases and one IVNKTCL case (total 46%) were found to have normal karyotypes, and the cytogenetic abnormalities observed in the other seven IVLBCL cases (54%) were investigated further. These seven karyotypes were uniformly complex with an average of 13 aberrations. The seven cases all had abnormalities involving chromosome 6, with 57% involving structural abnormalities at 6q13, and chromosome 8, with 43% involving abnormalities at 8p11.2. In addition, 71% had aberrations at 19q13. On average, 4.4 chromosomal gains and losses were detected per case. Cytogenetic heterogeneities were observed in six cases (86%) and tetraploidy in three cases (43%). There was no significant difference in progression-free survival (p=0.92) and overall survival (p=0.61) between the IVLBCL cases with complex and normal karyotypes.

CONCLUSION

Approximately half of IVLBCL cases had a highly heterogeneous pattern of karyotypes with different clonal numerical and structural chromosome aberrations.

Intralymphatic histiocytosis in healing cellulitis: Case report and review of the literature

Intralymphatic histiocytosis (ILH) is a rare skin benign condition observed in a variety of inflammatory settings. It is characterized by the presence of ectatic dermal lymphatic vessels containing aggregates of histiocytes. Associated conditions that have been identified include rheumatoid arthritis, metallic orthopedic implants, inflammatory bowel disease, and malignancies of the breast, skin, and colon. Some cases with no attributable underlying cause have been described. The pathophysiology of ILH is not well understood. It has been proposed that it may represent macrophage migration during immune activation. Herein, we present the first description of ILH observed in the healing phase of cellulitis on the skin of the breast. Awareness of this possibility is important when the diagnosis of intravascular carcinomatosis is being considered.

Transcriptome complexity in intravascular NK/T-cell lymphoma

AIMS

Intravascular NK/T-cell lymphoma (IVNKTCL) is a rare disease, which is characterised by exclusive growth of large cells within the lumen of small vessels, Epstein-Barr virus infection and somatic mutations in epigenetic regulator genes. Here, we elucidate the transcriptomic complexity of IVNKTCL.

METHODS

IVNKTCL cases were retrieved from a single-centre cohort of 25 intravascular lymphomas. RNA-seq and whole exome sequencing (WES) were performed to analyse transcriptomic abnormalities and mutations in splicing factors.

RESULTS

Approximately 88% of the total reads from the RNA-seq were considered exonic, while the remaining reads (12%) were mapped to intronic or intergenic regions. We detected 28,941 alternative splicing events, some of which would produce abnormal proteins rarely found in normal cells. The detected events also included tumour-specific splicing alterations in oncogenes and tumour suppressors (e.g., HRAS, MDM2 and VEGFA). WES identified premature termination mutations or copy number losses in a total of 15 splicing regulator genes, including SF3B5, SRSF12 and TNPO3.

CONCLUSIONS

This study raises the possibility that IVNKTCL may be driven by multiple complex regulatory loops, including non-exonic expression and aberrant splicing, in addition to defects in epigenetic regulation.

Activated-cytotoxic TCRαβ+CD4+ peripheral T-cell lymphoma with hypodermal localization: Case report of a lymphoproliferative disorder probably evolved from the CD4+ cytotoxic T-cell subpopulation

The World Health Organization (WHO) classification of hematopoietic and lymphoid tumors identifies distinctive subtypes of peripheral T-cell lymphoma (PTCL), and, additionally, some PTCLs involving mostly extranodal sites like the skin. The difficulty of classifying PTCLs according to the normal stages of T-cell differentiation and the lack of definitive diagnostic markers for most of the subtypes make the diagnosis of these diseases challenging. PTCL cases which do not fit into any of the specifically defined entities are categorized as PTCL not otherwise specified (PTCL-NOS). PTCLs-NOS represent less than 2% of the total cases of T-cell lymphoma involving the skin. This article illustrates a case of a PTCL-NOS in which tumor cells have an activated cytotoxic TCRαβ+CD3+CD4+CD56+ T-cell phenotype and histopathologic features of subcutaneous panniculitis-like T-cell lymphoma, leading to a fatal outcome.

Pediatric Subcutaneous Panniculitis-like T-Cell Lymphoma With Hemophagocytosis Showing Complete Resolution With the BFM90 Protocol: Case Report and Review of Literature

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a distinct subtype of peripheral T-cell lymphoma associated with aggressive clinical behavior. Since its original description, it has continued to be a rare disease, and <200 cases have been reported in literature. We report an 11-year-old boy who presented with SPTCL and hemophagocytic lymphohistiocytosis (HLH) and responded to high-dose multiagent chemotherapy. He presented with steroid refractory erythematous, raised plaques over his face, trunk, and limbs over a period of 15 months treated elsewhere. Repeat evaluation in our center was consistent with SPTCL with features of HLH. He was initiated on therapy with the BFM90 protocol, which led to complete morphologic and biochemical remission. No single-best treatment regimen has been described for SPTCL with HLH in literature, and high-dose chemotherapy has shown good long-term remissions in the literature. The presence of SPTCL with HLH and systemic symptoms should prompt treatment with high-dose multiagent chemotherapy rather than Cyclophosphamide, Vincristine, Adriamycin, Prednisolone-like therapy. BFM90 is one such regimen that is well tolerated, and it can induce significant clinical and biochemical responses.

Intravascular NK/T-cell lymphoma: clinicopathological and integrated molecular analysis of two cases provides a clue to disease pathogenesis

Aims

To elucidate the clinicopathological and molecular features of intravascular NK/T-cell lymphoma (IVNKTCL).

Methods

Two cases of IVNKTCL were retrieved from a single-centre cohort composed of 25 intravascular lymphomas. Whole-exome and RNA sequencing and immunohistochemistry were performed.

Results

We identified somatic mutations in the following epigenetic regulators: four histone genes (HIST1H2AN, HIST1H2BE, HIST1H2BN and H3F3A), histone deacetylase (HDAC5), two helicases (WRN and DDX3X), two methylation-related enzymes (TET2 and DNMT1) and the SNI/SWF pathway (ARID1A). Copy number analysis identified driver gene alterations comprising the loss of ARID1B, HACE1 and SMAD4, and the gain of SOX2 and histone clusters. RNA sequencing analysis did not indicate the presence of any fusion gene. Both cases were positive for Epstein-Barr virus (EBV) and showed strong expression of programmed death-ligand 1 (PD-L1).

Conclusions

This study raises the possibility that, at least for some patients, IVNKTCL may be considered an epigenetic disease with EBV infection-associated aetiopathogenesis.

CD4/CD8 Double-negative Mycosis Fungoides: A Case Report and Literature Review

Mycosis fungoides, the most common subtype of cutaneous T-cell lymphoma, displays a broad spectrum of clinical, histological and phenotypic variants with different prognostic impacts. The classic immunophenotype is CD3+/CD4+/CD45RO+memory T cells. CD4/CD8 double-negative mycosis fungoides is rare. Here we describe the clinicopathological features of CD4/CD8 double-negative mycosis fungoides in a 55-year-old female with a review of the literature. Although the CD4/CD8 double-negative phenotype appears to be associated with an unusual clinical presentation, it does not appear to confer prognostic significance.

Rare T-Cell Subtypes

There are a number of rare T-cell lymphoma subtypes that may be encountered in clinical practice. In recent years, improved immunohistochemical techniques and molecular tumor profiling have permitted refinement of some of the diagnostic categories in this group, as well as the recognition of distinct conditions not previously well elucidated. In this chapter, we cover the diagnostic and clinical features of some of the more common of these conditions, including subcutaneous panniculitis-like T-cell lymphoma, cutaneous gamma-delta T-cell lymphoma, enteropathy-associated T-cell lymphoma, monomorphic epitheliotropic intestinal T-cell lymphoma, primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma, CD4-positive small/medium T-cell lymphoproliferative disorder, and acral CD8-positive T-cell lymphoma. Given the rarity of these conditions, optimal treatments approaches are not always well established, not least as data from large-scale clinical trials are lacking. In this chapter, we aim to provide a summation of current thinking around best treatment, as well as highlighting some controversies in the management of these diagnoses.

Intravascular NK/T-cell lymphoma, Epstein-Barr virus positive with multiorgan involvement: a clinical dilemma

Background

Intravascular lymphoma is a rare type of non-Hodgkin lymphoma mostly of B-cell lineage. A few cases of intravascular lymphoma have been found to be of NK/T-cell origin, mainly affecting the skin and central nervous system.

Case presentation

A 54-year-old Caucasian man sought care because of a 2 weeks history of jaundice and intermittent fever, not responsive to antibiotics and antipyretics. Laboratory tests showed low blood oxygen concentration and pancytopenia. Serum microbiological tests were negative. Computerized tomography (CT) scan revealed hepatosplenomegaly and diffuse ground-glass opacities in both lungs without interlobular septal thickening. Despite oxygen therapy, the clinical conditions rapidly deteriorated leading to death 3 days after admission. Autopsy revealed a multiorgan involvement by an Epstein-Barr virus positive NK/T-cell lymphoma, strikingly growing within the blood vessel lumina, in absence of skin lesions.

Conclusions

The current case highlights the pathological features of this rare entity, the protean clinical presentation of which is often misleading, resulting in delayed diagnosis and treatment.

Successful Cord Blood Stem Cell Transplantation for Primary Cutaneous CD8-positive Aggressive Epidermotropic Cytotoxic T-cell Lymphoma Complicated with Cerebral Infiltration

A 16-year-old boy, who had been initially examined for bilateral blepharedema and slight eruption, presented with rapidly deteriorating symptoms in associating with headache and consciousness disturbance. He was diagnosed to have primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma (PCAE-CTL) by a biopsy of the skin and brain. After whole-brain radiation and some courses of chemotherapy, cord blood transplantation was performed with myeloablative conditioning. After transplantation, the cerebral dysfunction gradually improved. Disease remission was confirmed by the disappearance of any abnormal findings on electroencephalogram and magnetic resonance imaging. PCAE-CTL is reported to be an extremely aggressive disease with a poor prognosis, but the timely performance of cord blood transplantation is considered to be a promising treatment strategy.

Classification and Treatment of Rare and Aggressive Types of Peripheral T-Cell/Natural Killer-Cell Lymphomas of the Skin

Background

The classification of cutaneous lymphomas has been contentious. Two major competing classifications were the World Health Organization (WHO) and the European Organization for Research and Treatment of Cancer (EORTC). The principal authors met for a consensus meeting resulted in a combined classification called WHO-EORTC Classification of Cutaneous Lymphoma.

Methods

We review the classification of “mature” or peripheral T-cell lymphoma (PTCL) with high predilection to the skin as published by the WHO-EORTC. We also highlight new information and changes from the previous classifications of cutaneous PTCL according to the WHO classification or the EORTC classification. Finally, the salient findings are compared with similar-looking nodal PTCLs with a high frequency of skin involvement.

Results

This review focuses on a rare group of cutaneous PTCLs other than mycosis fungoides or its variants. Changes from the previous classifications are discussed, and the rare group of nodal PTCLs with high predilection to the skin are presented. The salient findings, diagnostic features, and treatments are included, along with summary tables and clinical-histopathologic images.

Conclusions

This review may serve as a guide for hematologists, oncologists and dermatologists in the diagnosis and management of these rare, aggressive, and often difficult to diagnose lymphomas. Although cutaneous lymphomas are morphologically identical to systemic lymphomas, the former behave differently, require divergent management, and should be recognized as separate entities. The consensus WHO-EORTC classification presents unified terminology and definitions to promote conformity in diagnosing and treating these cases, to foster a multidisciplinary approach to these often-obscure diseases, and to lead to more advances in identifying molecular targets specific to these entities.

Epstein-Barr Virus-associated Lymphoproliferative Disorders in the Skin

Epstein-Barr virus (EBV)-associated lymphoproliferations involving the skin are a rare but important group of diseases with a broad spectrum of behavior, ranging from self-limiting spontaneously resolving disorders to highly aggressive malignancies. They may be of B, T, or natural killer (NK) cell type and include EBV-positive mucocutaneous ulcer, lymphomatoid granulomatosis, EBV-positive diffuse large B-cell lymphoma, hydroa vacciniforme-like lymphoproliferative disorder, and extranodal NK/T-cell lymphoma of nasal type. Recognition and distinction of these entities is important in view of their differing prognoses and treatments. An association with EBV may be the first indication that a patient is immunosuppressed.

Cutaneous Lymphomas with Cytotoxic Phenotype

Primary cutaneous cytotoxic lymphomas are T-cell or natural killer-cell lymphomas that express 1 or more cytotoxic markers. These neoplasms constitute a spectrum of diseases. In this review, an overview of clinical, morphologic, and phenotypical features of each subtype is provided. Differential diagnosis is discussed with attention to scenarios in which diagnostic difficulties are most frequently encountered.

Clinical manifestations and pathogenesis of cutaneous lymphomas: current status and future directions

The primary cutaneous lymphomas are a heterogeneous group of T-, Natural Killer- and B- cell neoplasms with a wide range of clinical and pathological presentations, and with very different prognoses compared to systemic lymphomas. Recent studies have shown that the skin microenvironment, which is composed of various immune cell subsets as well as their spatial distribution and T-cell interactions through different chemokines and cytokines, has an important role in the development and pathogenesis of cutaneous lymphomas and has assisted in the development of novel and more effective immunotherapies. The following review will focus on the major subtypes of primary cutaneous lymphomas, including the clinical and histological patterns, molecular hallmarks, and current and future treatment strategies.

Primary cutaneous T-cell lymphomas: a review

Primary cutaneous T-cell lymphomas (CTCLs) represent a number of extranodal lymphomas arising from a malignant population of lymphocytes in the skin, with the most common type being mycosis fungoides (MF) representing half of all primary CTCLs. Despite advances in immunohistochemistry and molecular methodology, significant diagnostic challenges remain due to phenotypic overlap of primary CTCLs with several inflammatory dermatoses, secondary lymphomas, among other conditions. Clinical features such as presentation and morphology, staging, histology, immunophenotype and molecular features must be considered in detail before a diagnosis is made in order to minimise false-positive, false-negative and indeterminate diagnoses. Herein, we review primary CTCLs, including epidemiological data, a brief summary of clinical presentations, immunophenotype, molecular signatures and differential diagnoses.

Primary cutaneous lymphomas: diagnosis and treatment

Primary cutaneous lymphomas (CLs) are a heterogeneous group of lymphoproliferative neoplasms, with lymphatic proliferation limited to the skin with no involvement of lymph nodes, bone marrow or viscera at the diagnosis. Cutaneous lymphomas originate from mature T-lymphocytes (65% of all cases), mature B-lymphocytes (25%) or NK cells. Histopathological evaluation including immunophenotyping of the skin biopsy specimen is the basis of the diagnosis, which must be complemented with a precise staging of the disease and identification of prognostic factors, to allow for the choice of the best treatment method as well as for the evaluation of the treatment results.

Cutaneous Intravascular NK/T-cell lymphoma mimic panniculitis clinically, case report and literature brief review

Intravascular large cell lymphoma is a rare subtype of extranodal large cell lymphoma characterized by the presence of neoplastic cells within the lumina of small vessels. Most cases of intravascular large cell lymphoma have a B-cell phenotype. To date, 12 cases of intravascular natural killer (NK/)/T–cell lymphoma (IVNKL) have been reported. Our case is A 47-year-old female presented with erythematous patches and plaques on the lower extremities mimicking panniculitis clinically. A skin biopsy revealed intravascular lymphoma (IVL) with a NK/T cell phenotype (positive for CD3, and granzyme B and negative for CD20, CD4, CD8, CD5). The lymphoma cells were also positive for Epstein-Barr virus by Epstein-Barr virus-encoded RNA in situ hybridization test. Because this type of lymphoma is extremely rare, our case is documented and compared with the previously reported cases.

Intravascular NK-cell lymphoma: a case report and review of the literature

Background

Intravascular NK-cell lymphoma (IVNKL) is an extremely rare variant of non-Hodgkin lymphoma. To our knowledge, there are only a few cases reported in the English literature. Here, a case of a 29-year-old male with IVNKL involving the skin of the trunk and 4 extremities and liver is presented. A comprehensive literature review is undertaken to summarize the clinical and pathological features of this disorder.

Findings

In our case, large neoplastic lymphoid cells are restricted to the lumen of small vessels and exhibit the phenotype of a true NK cell. The morphology and immunophenotype, positivity of EBER and NK-cell origin are similar to other IVNKL cases. In addition, some cases including ours carry a poor prognosis as multiple systems or vital organs are involved.

Conclusion

In summary, we report a case of an unusual intravascular lymphoma of NK-cell lineage that displays both clinical and pathological features and compare it with other differential diagnoses. It is important to recognize this rare entity to make an appropriate diagnosis and achieve a better understanding regarding the treatment and prognosis.

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.

Pediatric subcutaneous panniculitis-like T-cell lymphoma with favorable result by immunosuppressive therapy: a report of two cases

Subcutaneous panniculitis-like T-cell lymphoma (SPTL) is a rare type of skin lymphoma. Histopathology mimicking a lobular panniculitis makes it difficult to distinguish SPTL from benign autoimmune disease. We present cases of a 10-year-old female and an 11-year-old male with SPTL showing recurrent panniculitis and systemic manifestations. Initially, antibiotics and steroids were administered to treat infectious disease and benign panniculitis. However, they experienced recurrent fever and erythema nodosum. Additional immunohistochemistry and T-cell receptor (TCR) gene rearrangement analyses were performed, enabling the establishment of an SPTL diagnosis. The affected patients were given immunosuppressive therapy with favorable results.