Lymphomatoid Papulosis With T-cell Receptor-Gamma Delta Expression: A Clinicopathologic Case-series of 26 Patients of an Underrecognized Immunophenotypic Variant of Lymphomatoid Papulosis

Lymphomatoid papulosis (LyP) has several histopathologic presentations. LyP featuring gamma-delta (γδ) T-cell receptor expression may masquerade as and may be misdiagnosed as aggressive cutaneous T-cell lymphoma, particularly primary cutaneous γδ T-cell lymphoma (PCGDTL) or γδ mycosis fungoides. We performed a clinicopathologic analysis of the largest series of LyP featuring γδ T-cell expression. We identified 26 patients with a diagnosis of LyP with γδ T cells from our institutions, as well as through a comprehensive review of the literature, and characterized these cases. Most cases were treated with topical steroids or not treated at all. The majority of cases showed a CD4 - CD8 + phenotype and featured at least one cytotoxic marker. Histopathologic features included an intraepidermal or dermal infiltrate with large cells and frequent angiotropism. One case was initially misdiagnosed as PCGDTL, requiring further therapy. Our case series, the largest international cohort of γδ T cell predominant LyP cases, confirms marked clinicopathologic heterogeneity that may contribute to misdiagnosis, reasserting the need to identify classic clinical features, CD30 + T-cell components, and markers of cytotoxicity when dealing with this differential diagnosis. A limitation of this study includes somewhat limited follow-up, histologic, and immunophenotypic information for some cases.

Classifications of cutaneous lymphomas and lymphoproliferative disorders: An update from the EORTC cutaneous lymphoma histopathology group

The classification of primary cutaneous lymphomas and lymphoproliferative disorders (LPD) is continuously evolving by integrating novel clinical, pathological and molecular data. Recently two new classifications for haematological malignancies including entities of cutaneous lymphomas were proposed: the 5th edition of the WHO classification of haematolymphoid tumours and the International Consensus Classification (ICC) of mature lymphoid neoplasms. This article provides an overview of the changes introduced in these two classifications compared to the previous WHO classification. The main changes shared by both classifications include the downgrading of CD8+ acral T-cell lymphoma to CD8+ acral T-cell LPD, and the recognition of entities that were previously categorized as provisional and have now been designated as definite types including primary cutaneous small or medium CD4+ T-cell LPD, primary cutaneous gamma/delta T-cell lymphoma, primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma, Epstein-Barr virus-positive mucocutaneous ulcer. Both classifications consider primary cutaneous marginal zone B-cell clonal neoplasm as an indolent disease but use a different terminology: primary cutaneous marginal zone lymphoma (WHO) and primary cutaneous marginal zone LPD (ICC). The 5th WHO classification further introduces and provides essential and desirable diagnostic criteria for each disease type and includes chapters on reactive B- or T-cell rich lymphoid proliferations formerly referred as cutaneous pseudolymphomas, as well as histiocyte and CD8 T-cell rich LPD in patients with inborn error of immunity. As already emphasized in previous lymphoma classifications, the importance of integrating clinical, histological, phenotypic and molecular features remains the crucial conceptual base for defining cutaneous (and extracutaneous) lymphomas.

Foamy Macrophages in a Case of Mononucleosis With Amoxicillin-Induced Rash, Hyperlipidemia, and Hemophagocytic Lymphohistiocytosis

ABSTRACT

A 38-year-old man presented with fever, cough, and jaundice. Four days before, he had started taking amoxicillin/clavulanic acid. He subsequently developed a morbilliform rash, and, according to clinical features and blood analyses, a diagnosis of mononucleosis with Epstein-Barr virus-associated antibiotic-induced exanthema and secondary hemophagocytic lymphohistiocytosis was made. A skin biopsy revealed a superficial perivascular lymphohistiocytic infiltrate with interface dermatitis and many foamy macrophages in the papillary dermis and around the vessels of the superficial dermal plexus. A blood lipid test uncovered marked hypercholesterolemia and hypertriglyceridemia. After treatment with dexamethasone and immunoglobulin, the skin rash, liver function, and lipid profile progressively improved. Xanthomatous cells have been observed in skin biopsies of acute graft-versus-host disease with liver involvement, and these cells have been suggested to represent a clue to the presence of hepatic disease. In our case, underlying cholestatic hepatopathy with hyperlipidemia was present. We believe that the incidental finding of foamy cells in graft-versus-host disease cases and in our case are likely related to the presence of severe liver disease with cholestatic hepatopathy and secondary hyperlipidemia in different background conditions.

Identifying and addressing unmet clinical needs in primary cutaneous B-cell lymphoma: A consensus-based paper from an ad-hoc international panel

Primary cutaneous B-cell lymphomas (PCBCLs) are lymphoproliferative disorders that appear on the skin without evidence of extracutaneous manifestations at the time of diagnosis. There is a lack of evidence-based guidelines for their clinical management due to the availability of very few large scale studies and controlled clinical trials. Here we present and discuss a series of major unmet clinical needs (UCNs) in the management of PCBCLs by a panel of 16 experts involved in research and clinical practice of PCBCL. The Panel produced recommendations on the appropriateness of the clinical decisions concerning the identified clinical needs and proposed research for improving the knowledge needed to solve them. Recommendations and proposals were achieved by multiple-step formalized procedures to reach a consensus after a comprehensive analysis of the scientific literature. Recommendations and proposals lay in the domain of classification uncertainties of PCBCL, optimization of diagnosis, optimization of prognosis, optimization of staging and critical issues on therapeutic strategies with particular focus on new treatments. These recommendations are intended for use not only by experts but above all by dermatologists and hematologists with limited experience in the field of PCBCLs as well as general practitioners.

Nodular-Type Lichen Myxedematosus: A Rare Variant With Exclusive Involvement of the Hands-Report of Two Cases With a Comprehensive Review of the Literature

ABSTRACT

Lichen myxedematosus (LM) is an uncommon cutaneous mucinosis characterized by the deposition of mucin and fibroblast proliferation in the dermis. This condition can be classified into 2 forms: a diffuse/generalized LM, also known as scleromyxedema, associated with monoclonal gammopathy and systemic implications, and a localized form, primarily affecting the skin. Within the localized form, nodular-type LM is a rare variant presenting as firm, skin-colored to pinkish mucinous nodules. In this article, we report 2 new cases of nodular-type LM with exclusive involvement of the hands and provide a comprehensive review of the diagnosis, histopathological aspects, and therapeutic considerations of this rare condition.

Clinical and Pathological Spectrum of Prurigo Pigmentosa in Central European Individuals

Importance

Based on early studies, prurigo pigmentosa (PP) was considered a rare inflammatory dermatosis affecting primarily Asian individuals. However, several case reports subsequently showed that the disease is not restricted to those of Asian origin. Large studies on PP in central European individuals, on the other hand, are missing.

Objective

To increase awareness of PP by describing the clinical, histopathological, and immunohistochemical features in central European individuals.

Design, Setting, and Participants

This observational, retrospective case series analyzed clinicopathological features of 20 central European patients diagnosed with PP. Data collection was performed by means of archive material, including physician's letters, clinical photographs, and histopathological records, at the Department of Dermatology at the Medical University of Graz in Austria from January 1998 to January 2022.

Main Outcomes and Measures

Demographic, clinical, histopathological, and immunohistochemical characteristics for patients diagnosed with PP were recorded.

Results

Of the 20 patients included, 15 (75%) were female, and the mean (range) age was 24.1 (15-51) years. The study cohort consisted entirely of European patients. The most common site of involvement of PP was the breast, followed by the neck and back. Other involved clinical sites were the abdomen, shoulders, face, head, axillae, arms, and genital region and groin. Clinically, lesions were characterized by a symmetric pattern in 90% (n = 18) of all cases. Marked hyperpigmentation was observed only in 25% (n = 5) of patients. In some cases, triggers such as malnutrition, long-term pressure, and friction were noted. Histologic findings revealed presence of neutrophils in all cases and necrotic keratinocytes in 67% (n = 16) of cases. Immunohistochemistry results showed predominance of CD8+ lymphocytes in the epidermis, as well as the presence of plasmacytoid dendritic cells and myeloid cell nuclear differentiation antigen-positive neutrophil precursors.

Conclusions and Relevance

This case series found that most clinical features observed in Asian patients were also observed in central European patients, but hyperpigmentation was primarily mild to moderate. Histopathological features were similar to those reported in the literature with the additional presence of myeloid cell nuclear differentiation antigen-positive precursor neutrophils. These results expand previous knowledge about PP in central European individuals.

A Microenvironment-Related Nine-Gene Signature May Predict Survival in Mycosis Fungoides Patients at Diagnosis

Mycosis fungoides (MF) is the most common cutaneous lymphoma characterized by an indolent course. Prognosis is stage-based but this approach does not reflect the different outcomes within stages. Considering that tumor microenvironment is known to be involved in MF pathogenesis and progression, we decided to investigate 99 MF cases by using the PanCancer Immune Profiling Panel. We identified and validated a signature of 9 genes able to predict MF survival and distinguish a high-risk group with a worse outcome from a low-risk group of cases with a better outcome. At the molecular level, low-risk vs. high-risk cases reported a global upregulation of immune genes, enriched in cytokines, and a higher density of dendritic cells and mast cells, possibly associated with a more favorable clinical course.

CD68+ and CD8+ immune cells are associated with the growth pattern of somatotroph tumors and response to first generation somatostatin analogs

Somatotropinomas are pituitary tumors with a heterogenous clinical behavior. The tumor microenvironment regulates the interaction between tumor cells and the host immune system, potentially modulating tumor behavior. Here, we aimed to investigate the tumor immune infiltration in a cohort of medically naïve acromegaly patients. A retrospective, monocenter study was designed to analyze the presence of CD3+, CD20+, CD138+, CD4+, CD8+, CD68+ immune cells in samples of somatotropinomas and their prognostic significance on tumor behavior and response to first generation somatostatin analogs (fg-SSA). Thirty-six patients (23 females) were included in the study. Macroadenomas were identified in 23 cases: 12 with cavernous sinus invasion. The number of CD8+ lymphocytes positively correlated with CD4+ lymphocytes (p = .05, r:0.245) and with CD68+ macrophages (p = .01, r = 0.291). The CD8+/CD4+ ratio inversely correlated with CD68+/CD8+ ratio (p < .001, r = -0.626). CD68+ macrophages positively correlated with tumor size (maximum diameter p = .003, r = 0.574; volume p = .009, r = 0.566) and were more numerous in somatotropinomas with Ki-67 > 3% (median 65/HPF, IQR:15), compared to cases with Ki67 < 3% (median 50/HPF, IQR:22, p < .001). CD8+ and CD138+ lymphocytes were more numerous in cases responsive to fg-SSA (respectively median 18/HPF IQR:18 and median 8/HPF IQR: 6.5) as compared to fg-SSA nonresponsive cases (median 14.5/HPF IQR:40 p = .03; median 3.5/HPF IQR: 14 p = .03). CD8+ lymphocytes act as single predictor of response to fg-SSA, independently from age, GH and IGF-I levels, tumor dimension and invasion. Our results support that lymphocytes and macrophages generate an immune network in somatotropinomas and the characteristic of the immune infiltrate may predict treatment outcome.

Concurrent Presentation of Mycosis Fungoides and Primary Cutaneous Marginal Zone LPD: Clinicopathological Study of 4 Cases and Literature Review

BACKGROUND

Mycosis fungoides is rarely associated to B-cell malignancies, and the few reported cases are mainly internal lymphomas involving secondarily the skin (ie, chronic lymphocytic leukemia).

OBJECTIVES

The aim of our study is to describe the clinical and histopathological features of 4 patients presenting with 2 concurrent primary cutaneous lymphomas and review the pertinent literature.

METHODS

We identified 4 cases of concurrent primary cutaneous lymphomas in our institutions. An extracutaneous lymphoma was ruled out on the basis of a complete work out. We performed a PubMed search to identify reported cases of primary cutaneous composite or concurrent lymphomas.

RESULTS

Eleven cases of primary cutaneous concurrent lymphomas have been described in the literature. Counting all together (our cases and the cases previously described in the literature), mycosis fungoides was the most frequent primary cutaneous T-cell lymphoma (TCL) (13/15), followed by 1 case of peripheral TCL-NOS and 1 case of subcutaneous panniculitis-like TCL. Regarding the associated primary cutaneous B-cell lymphomas, 8/15 cases consisted of low-grade B-cell lymphomas [that is, 5 marginal zone lymphoma (in the most recent classification reclassified as marginal zone lymphoproliferative disorder, MZLD, 2 follicular-center B-cell lymphoma (primary cutaneous follicle-center lymphoma) and 1 low-grade NOS B-cell lymphoma]; 4/15 were associated to Epstein-Barr virus; 1 case consisted of a methotrexate-associated lymphoproliferative disease, and 2 cases consisted of primary cutaneous diffuse large B-cell lymphoma-leg type.

CONCLUSIONS

Primary cutaneous concurrent lymphomas are exceptional. Clinicopathological correlation and a complete workout to reach the correct diagnosis may guide the appropriate treatment in each case.

Dermatopathologic features of cutaneous squamous cell carcinoma and actinic keratosis: Consensus criteria and proposed reporting guidelines

BACKGROUND

There is considerable variation in the literature regarding the dermatopathologic diagnostic features of and reporting guidelines for actinic keratosis (AK) and cutaneous squamous cell carcinoma (cSCC).

OBJECTIVE

To develop consensus recommendations regarding diagnostic criteria, nomenclature, and reporting of AK and cSCC.

METHODS

Literature review and cross-sectional multiround Delphi process including an international group of expert dermatopathologists followed by a consensus meeting.

RESULTS

Consensus was achieved regarding the key dermatopathologic features necessary for diagnosing cSCC, AK, and associated variants; grading of degree of cellular differentiation in cSCC; utility of immunohistochemistry for diagnosis of cSCC; and pathologic features that should be reported for cSCC and AK.

LIMITATIONS

Consensus was not achieved on all questions considered.

CONCLUSION

Despite the lack of clarity in the literature, there is consensus among expert dermatopathologists regarding diagnostic criteria and appropriate reporting of AK and cSCC. Widespread implementation of these consensus recommendations may improve communication between dermatopathologists and clinicians, facilitating appropriate treatment of AK and cSCC.

Essential thrombocythemia manifesting as livedoid and purpuric skin lesions: Report of two cases and literature review

Essential thrombocythemia is a chronic myeloproliferative syndrome which usually courses with an asymptomatic excess platelet count. Cutaneous manifestations secondary to microcirculation abnormalities are rare but can represent a helpful diagnostic clue in order to prevent major thromboembolic events. We report two cases of heterogeneous livedoid and "net-like" skin lesions in the context of essential thrombocythemia with identical histopathologic findings (lumina obliteration by eosinophilic material, mostly positive for CD61 platelet stain, without vasculitis of medium-sized skin vessel). In conclusion, we seek to raise awareness of the clinicopathological features of essential thrombocythemia to allow for prompt diagnosis and treatment. This article is protected by copyright. All rights reserved.

Human Papillomavirus 42 Drives Digital Papillary Adenocarcinoma and Elicits a Germ Cell-like Program Conserved in HPV-Positive Cancers

The skin is exposed to viral pathogens, but whether they contribute to the oncogenesis of skin cancers has not been systematically explored. Here we investigated 19 skin tumor types by analyzing off-target reads from commonly available next-generation sequencing data for viral pathogens. We identified human papillomavirus 42 (HPV42) in 96% (n = 45/47) of digital papillary adenocarcinoma (DPA), an aggressive cancer occurring on the fingers and toes. We show that HPV42, so far considered a nononcogenic, "low-risk" HPV, recapitulates the molecular hallmarks of oncogenic, "high-risk" HPVs. Using machine learning, we find that HPV-driven transformation elicits a germ cell-like transcriptional program conserved throughout all HPV-driven cancers (DPA, cervical carcinoma, and head and neck cancer). We further show that this germ cell-like transcriptional program, even when reduced to the top two genes (CDKN2A and SYCP2), serves as a fingerprint of oncogenic HPVs with implications for early detection, diagnosis, and therapy of all HPV-driven cancers.

SIGNIFICANCE

We identify HPV42 as a uniform driver of DPA and add a new member to the short list of tumorigenic viruses in humans. We discover that all oncogenic HPVs evoke a germ cell-like transcriptional program with important implications for detecting, diagnosing, and treating all HPV-driven cancers. See related commentary by Starrett et al., p. 17. This article is highlighted in the In This Issue feature, p. 1.

Recent advances in cutaneous lymphoma-implications for current and future classifications

The Revised European-American Classification of mature lymphoid neoplasms published in 1994 and the 2001, 2008 and 2016 WHO classifications that followed, were the product of international collaboration and consensus amongst haematopathologists, geneticists, molecular scientists and clinicians. Primary cutaneous lymphomas were fully incorporated into this process following the publication of the WHO-EORTC classification of cutaneous lymphomas in 2005. The definition, diagnostic criteria and recommended studies for primary cutaneous lymphoma continue to be refined. The 2022 International Consensus Classification represents the most recent update and an overview of all the main entities presenting primarily in the skin, together with the major changes in classification, are summarized herein. Primary cutaneous marginal zone lymphoma is segregated from other extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma) and downgraded to a lymphoproliferative disorder in line with its markedly indolent behaviour. In addition, two subtypes are recognised, based largely but not exclusively on whether they are heavy chain class-switched or IgM positive. Similarly, in keeping with a trend to greater conservatism, primary cutaneous acral CD8 positive T cell lymphoma is now also classified as a lymphoproliferative disorder. In addition, significant new insights into the biology of primary cutaneous lymphoma have also recently been forthcoming and will be presented. These studies have enhanced our knowledge of genetic, epigenetic and transcriptional changes in this group of diseases. They not only identify potential targets for novel therapies, but also raise as yet unanswered questions as to how we categorise cutaneous lymphomas, particularly with respect to relationships with similar lymphomas at extracutaneous sites.

Blocking STAT3/5 through direct or upstream kinase targeting in leukemic cutaneous T-cell lymphoma

Leukemic cutaneous T-cell lymphomas (L-CTCL) are lymphoproliferative disorders of skin-homing mature T-cells causing severe symptoms and high mortality through chronic inflammation, tissue destruction, and serious infections. Despite numerous genomic sequencing efforts, recurrent driver mutations have not been identified, but chromosomal losses and gains are frequent and dominant. We integrated genomic landscape analyses with innovative pharmacologic interference studies to identify key vulnerable nodes in L-CTCL. We detected copy number gains of loci containing the STAT3/5 oncogenes in 74% (n = 17/23) of L-CTCL, which correlated with the increased clonal T-cell count in the blood. Dual inhibition of STAT3/5 using small-molecule degraders and multi-kinase blockers abolished L-CTCL cell growth in vitro and ex vivo, whereby PAK kinase inhibition was specifically selective for L-CTCL patient cells carrying STAT3/5 gains. Importantly, the PAK inhibitor FRAx597 demonstrated encouraging anti-leukemic activity in vivo by inhibiting tumor growth and disease dissemination in intradermally xenografted mice. We conclude that STAT3/5 and PAK kinase interaction represents a new therapeutic node to be further explored in L-CTCL.

The International Consensus Classification of Mature Lymphoid Neoplasms: a report from the Clinical Advisory Committee

Since the publication of the Revised European-American Classification of Lymphoid Neoplasms in 1994, subsequent updates of the classification of lymphoid neoplasms have been generated through iterative international efforts to achieve broad consensus among hematopathologists, geneticists, molecular scientists, and clinicians. Significant progress has recently been made in the characterization of malignancies of the immune system, with many new insights provided by genomic studies. They have led to this proposal. We have followed the same process that was successfully used for the third and fourth editions of the World Health Organization Classification of Hematologic Neoplasms. The definition, recommended studies, and criteria for the diagnosis of many entities have been extensively refined. Some categories considered provisional have now been upgraded to definite entities. Terminology for some diseases has been revised to adapt nomenclature to the current knowledge of their biology, but these modifications have been restricted to well-justified situations. Major findings from recent genomic studies have impacted the conceptual framework and diagnostic criteria for many disease entities. These changes will have an impact on optimal clinical management. The conclusions of this work are summarized in this report as the proposed International Consensus Classification of mature lymphoid, histiocytic, and dendritic cell tumors.

[Orchiectomy due to early syphilis]

Granulomatous and abscessing testicular inflammations are important differential diagnoses of testicular tumors. Infectious orchitis should always be considered in unclear testicular masses with negative tumor markers. We report the case of a 45-year-old man with abscessing orchitis due to early syphilis diagnosed after orchiectomy with the suspicion of a seminoma.

[Uncommon presentation of psoriasis vulgaris in an 11-year-old patient]

Die Psoriasis vulgaris tritt mit einer Prävalenz von bis zu 2 % im Kindes- und Jugendalter auf. Größtenteils wird die Diagnose klinisch gestellt. Wir berichten über einen pädiatrischen Patienten, welcher uns aufgrund der für eine Psoriasis vulgaris eher untypischen Lokalisation vor eine diagnostische Herausforderung stellte. Diskutiert werden die wichtigsten Differenzialdiagnosen der verschiedenen Psoriasisformen sowie die aktuellen Therapieempfehlungen im Kindes- und Jugendalter.

Clinical, histopathological and prognostic features of primary cutaneous acral CD8+ T-cell lymphoma and other dermal CD8+ cutaneous lymphoproliferations - Results of an EORTC Cutaneous Lymphoma Group Workshop

BACKGROUND

The differential diagnosis of atypical dermal non-epidermotropic CD8+lymphocytic infiltrates includes a heterogenous spectrum of lymphoproliferations with overlapping histological and phenotypic features, but divergent clinical manifestations and prognoses. As these neoplasms are rare, more data on their clinicopathological presentation and course are needed.

OBJECTIVES

To assess the clinical, histological, immunophenotypic features, outcome of and differences between dermal CD8+ lymphoproliferations.

METHODS

Retrospective analysis of a series of 47 patients and biopsies by the international EORTC Cutaneous Lymphoma Group.

RESULTS

The dermal CD8+ lymphoproliferations (n=46) could be assigned to one of the following 3 groups: (1) cutaneous acral CD8+ T-cell lymphoma (n=31), characterized mostly by a solitary nodule arising at acral sites, a monotonous dermal infiltrate of small to medium-sized CD8+ lymphocytes with a characteristic dot-like pattern of CD68, a low proliferation rate and an excellent prognosis; (2) primary cutaneous CD8+ peripheral T-cell lymphoma, unspecified/NOS (n=11), presenting with one or multiple rapidly evolving tumors, mostly medium-sized pleomorphic CD8+ tumor cells with expression of several cytotoxic markers and high proliferative activity. After chemotherapy or radiotherapy relapses occurred in one third and 1 of 11 patients died due to lymphoma (9%); (3) The third group (n=4) comprised cutaneous CD8+ lymphoproliferations associated with congenital immunodeficiency syndromes in 2 patients with persisting localized or disseminated violaceous to brownish plaques on the extremities, a histiocyte-rich infiltrate of mostly small CD8+ lymphocytes with subtle atypia and a protracted course, and papular CD8+ eruptions in two patients with acquired immunosuppression (HIV-infection, solid organ transplantation).

CONCLUSIONS

A constellation of distinct clinical, histopathologic and phenotypic features allows discrimination and assignment of dermal CD8+ infiltrates to distinct disease entities including cutaneous acral CD8+ T-cell lymphoma, primary cutaneous CD8+ peripheral T-cell lymphoma, unspecified/NOS and cutaneous CD8+ lymphoproliferations associated with congenital or acquired immunodeficiency syndromes. Primary cutaneous acral CD8+ lymphoma, assigned a provisional category in current lymphoma classifications, is a distinct and reproducible entity. A correct diagnosis is essential to avoid unnecessarily aggressive treatment for indolent CD8+ lymphoproliferations and to identify cases with underlying immunodeficiency or potential for dismal outcome.

E-Cadherin Expression and Blunted Interferon Response in Blastic Plasmacytoid Dendritic Cell Neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive neoplasm derived from plasmacytoid dendritic cells (pDCs). In this study, we investigated by immunohistochemical analysis the expression of E-cadherin (EC) on pDCs in reactive lymph nodes and tonsils, bone marrow, and in BPDCN. We compared the expression of EC in BPDCN to that in leukemia cutis (LC) and cutaneous lupus erythematosus (CLE), the latter typically featuring pDC activation. In BPDCN, we also assessed the immunomodulatory activity of malignant pDCs through the expression of several type I interferon (IFN-I) signaling effectors and downstream targets, PD-L1/CD274, and determined the extent of tumor infiltration by CD8-expressing T cells. In reactive lymph nodes and tonsils, pDCs expressed EC, whereas no reactivity was observed in bone marrow pDCs. BPDCN showed EC expression in the malignant pDCs in the vast majority of cutaneous (31/33 cases, 94%), nodal, and spleen localizations (3/3 cases, 100%), whereas it was more variable in the bone marrow (5/13, 38,5%), where tumor cells expressed EC similarly to the skin counterpart in 4 cases and differently in other 4. Notably, EC was undetectable in LC (n=30) and in juxta-epidermal pDCs in CLE (n=31). Contrary to CLE showing robust expression of IFN-I-induced proteins MX1 and ISG5 in 20/23 cases (87%), and STAT1 phosphorylation, BPDCN biopsies showed inconsistent levels of these proteins in most cases (85%). Expression of IFN-I-induced genes, IFI27, IFIT1, ISG15, RSAD2, and SIGLEC1, was also significantly (P<0.05) lower in BPDCN as compared with CLE. In BPDCN, a significantly blunted IFN-I response correlated with a poor CD8+T-cell infiltration and the lack of PD-L1/CD274 expression by the tumor cells. This study identifies EC as a novel pDC marker of diagnostic relevance in BPDCN. The results propose a scenario whereby malignant pDCs through EC-driven signaling promote the blunting of IFN-I signaling and, thereby, the establishment of a poorly immunogenic tumor microenvironment.

Super-enhancer-based identification of a BATF3/IL-2R-module reveals vulnerabilities in anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL), an aggressive CD30-positive T-cell lymphoma, comprises systemic anaplastic lymphoma kinase (ALK)-positive, and ALK-negative, primary cutaneous and breast implant-associated ALCL. Prognosis of some ALCL subgroups is still unsatisfactory, and already in second line effective treatment options are lacking. To identify genes defining ALCL cell state and dependencies, we here characterize super-enhancer regions by genome-wide H3K27ac ChIP-seq. In addition to known ALCL key regulators, the AP-1-member BATF3 and IL-2 receptor (IL2R)-components are among the top hits. Specific and high-level IL2R expression in ALCL correlates with BATF3 expression. Confirming a regulatory link, IL-2R-expression decreases following BATF3 knockout, and BATF3 is recruited to IL2R regulatory regions. Functionally, IL-2, IL-15 and Neo-2/15, a hyper-stable IL-2/IL-15 mimic, accelerate ALCL growth and activate STAT1, STAT5 and ERK1/2. In line, strong IL-2Rα-expression in ALCL patients is linked to more aggressive clinical presentation. Finally, an IL-2Rα-targeting antibody-drug conjugate efficiently kills ALCL cells in vitro and in vivo. Our results highlight the importance of the BATF3/IL-2R-module for ALCL biology and identify IL-2Rα-targeting as a promising treatment strategy for ALCL.

Anaplastic large cell lymphoma (ALCL) is an aggressive T-cell lymphoma often with poor prognosis. To identify genes defining ALCL cell state and dependencies, the authors here characterize ALCL-specific super-enhancers and describe the BATF3/IL-2R−module as a therapeutic opportunity for ALCL.

Newly-Discovered Neural Features Expand the Pathobiological Knowledge of Blastic Plasmacytoid Dendritic Cell Neoplasm

Simple Summary

For the first time, neuronal features are described in blastic plasmacytoid dendritic cell neoplasm (BPDCN) by a complex array of molecular techniques, including microRNA and gene expression profiling, RNA and Chromatin immunoprecipitation sequencing, and immunohistochemistry. The discovery of unexpected neural features in BPDCN may change our vision of this disease, leading to the designing of a new BPDCN cell model and to re-thinking the relations occurring between BPDCN and nervous system. The observed findings contribute to explaining the extreme tumor aggressiveness and also to propose novel therapeutic targets. In view of this, the identification, in this work of new potential neural metastatic inducers might open the way to therapeutic approaches for BPDCN patients based on the use of anti-neurogenic agents.

Abstract

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and highly aggressive hematologic malignancy originating from plasmacytoid dendritic cells (pDCs). The microRNA expression profile of BPDCN was compared to that of normal pDCs and the impact of miRNA dysregulation on the BPDCN transcriptional program was assessed. MiRNA and gene expression profiling data were integrated to obtain the BPDCN miRNA-regulatory network. The biological process mainly dysregulated by this network was predicted to be neurogenesis, a phenomenon raising growing interest in solid tumors. Neurogenesis was explored in BPDCN by querying different molecular sources (RNA sequencing, Chromatin immunoprecipitation-sequencing, and immunohistochemistry). It was shown that BPDCN cells upregulated neural mitogen genes possibly critical for tumor dissemination, expressed neuronal progenitor markers involved in cell migration, exchanged acetylcholine neurotransmitter, and overexpressed multiple neural receptors that may stimulate tumor proliferation, migration and cross-talk with the nervous system. Most neural genes upregulated in BPDCN are currently investigated as therapeutic targets.

Single-cell RNA sequencing profiling in a patient with discordant primary cutaneous B-cell and T-cell lymphoma reveals micromilieu-driven immune skewing

BACKGROUND

Primary cutaneous lymphomas comprise a heterogeneous group of B-cell and T-cell malignancies which often show an indolent course, but can progress to aggressive disease in a subset of patients. Diagnosis is often delayed owing to clinical and histopathological similarities with benign inflammatory conditions. Especially during early disease, cancer cells are present at relatively low percentages compared with the inflammatory infiltrate, an interplay that is currently only insufficiently understood.

OBJECTIVES

To improve diagnostics and perform molecular characterization of a complex type of primary cutaneous lymphoma.

METHODS

Single-cell RNA sequencing (scRNA-seq) was performed and combined with T-cell and B-cell receptor sequencing.

RESULTS

We were able to diagnose a patient with concurrent mycosis fungoides (MF) and primary cutaneous follicle centre lymphoma (PCFCL), appearing in mutually exclusive skin lesions. Profiling of tumour cells and the tissue microenvironment revealed a type-2 immune skewing in MF, most likely guided by the expanded clone that also harboured upregulation of numerous pro-oncogenic genes. By contrast, PCFCL lesions exhibited a more type-1 immune phenotype, consistent with its indolent behaviour.

CONCLUSIONS

These data not only illustrate the diagnostic potential of scRNA-seq, but also allow the characterization of specific clonal populations that shape the unique tissue microenvironment in clinically distinct types of lymphoma skin lesions.

Subcutaneous panniculitis-like T-cell lymphoma, lupus erythematosus profundus, and overlapping cases: molecular characterization through the study of 208 genes

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare cytotoxic cutaneous lymphoma. Differential diagnosis with lupus erythematosus panniculitis (LEP) can be challenging and overlapping cases have been described. In this study, we investigate whether gene expression profiling may or not identify markers that can be used to improve our understanding of the disease and to make a precise differential diagnosis. SPTCL, LEP, and overlapping cases were analyzed using a customized NanoString platform including 208 genes related to T-cell differentiation, stromal signatures, oncogenes, and tumor suppressor genes. Gene expression unsupervised analysis of the samples differentiated SPTCL from LEP samples. Most overlapping cases were clustered with LEP cases. Differentially expressed genes were observed when comparing SPTCL with LEP cases; and overlapping with LEP cases. Gene set enrichment analysis recognized gene sets defining each group. In conclusion, SPTCL and LEP have distinctive molecular profiles and the molecular background of overlapping cases more closely resembles LEP.

Treatment of early-stage mycosis fungoides: results from the PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) study

BACKGROUND

The PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) study is a prospective analysis of an international database. Here we examine front-line treatments and quality of life (QoL) in patients with newly diagnosed mycosis fungoides (MF).

OBJECTIVES

To identify (i) differences in first-line approaches according to tumour-nodes-metastasis-blood (TNMB) staging; (ii) parameters related to a first-line systemic approach and (iii) response rates and QoL measures.

METHODS

In total, 395 newly diagnosed patients with early-stage MF (stage IA-IIA) were recruited from 41 centres in 17 countries between 1 January 2015 and 31 December 2018 following central clinicopathological review.

RESULTS

The most common first-line therapy was skin-directed therapy (SDT) (322 cases, 81·5%), while a smaller percentage (44 cases, 11·1%) received systemic therapy. Expectant observation was used in 7·3%. In univariate analysis, the use of systemic therapy was significantly associated with higher clinical stage (IA, 6%; IB, 14%; IIA, 20%; IA-IB vs. IIA, P < 0·001), presence of plaques (T1a/T2a, 5%; T1b/T2b, 17%; P < 0·001), higher modified Severity Weighted Assessment Tool (> 10, 15%; ≤ 10, 7%; P = 0·01) and folliculotropic MF (FMF) (24% vs. 12%, P = 0·001). Multivariate analysis demonstrated significant associations with the presence of plaques (T1b/T2b vs. T1a/T2a, odds ratio 3·07) and FMF (odds ratio 2·83). The overall response rate (ORR) to first-line SDT was 73%, while the ORR to first-line systemic treatments was lower (57%) (P = 0·027). Health-related QoL improved significantly both in patients with responsive disease and in those with stable disease.

CONCLUSIONS

Disease characteristics such as presence of plaques and FMF influence physician treatment choices, and SDT was superior to systemic therapy even in patients with such disease characteristics. Consequently, future treatment guidelines for early-stage MF need to address these issues.

Should we be imaging lymph nodes at initial diagnosis of early-stage mycosis fungoides? Results from the PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) international study

BACKGROUND

Early-stage mycosis fungoides (MF) includes involvement of dermatopathic lymph nodes (LNs) or early lymphomatous LNs. There is a lack of unanimity among current guidelines regarding the indications for initial staging imaging in early-stage presentation of MF in the absence of enlarged palpable LNs.

OBJECTIVES

To investigate how often imaging is performed in patients with early-stage presentation of MF, to assess the yield of LN imaging, and to determine what disease characteristics promoted imaging.

METHODS

A review of clinicopathologically confirmed newly diagnosed patients with cutaneous patch/plaque (T1/T2) MF from PROspective Cutaneous Lymphoma International Prognostic Index (PROCLIPI) data.

RESULTS

PROCLIPI enrolled 375 patients with stage T1/T2 MF: 304 with classical MF and 71 with folliculotropic MF. Imaging was performed in 169 patients (45%): 83 with computed tomography, 18 with positron emission tomography-computed tomography and 68 with ultrasound. Only nine of these (5%) had palpable enlarged (≥ 15 mm) LNs, with an over-representation of plaques, irrespectively of the 10% body surface area cutoff that distinguishes T1 from T2. Folliculotropic MF was not more frequently imaged than classical MF. Radiologically enlarged LNs (≥ 15 mm) were detected in 30 patients (18%); only seven had clinical lymphadenopathy. On multivariate analysis, plaque presentation was the sole parameter significantly associated with radiologically enlarged LNs. Imaging of only clinically enlarged LNs upstaged 4% of patients (seven of 169) to at least IIA, whereas nonselective imaging upstaged another 14% (24 of 169). LN biopsy, performed in eight of 30 patients, identified N3 (extensive lymphomatous involvement) in two and N1 (dermatopathic changes) in six.

CONCLUSIONS

Physical examination was a poor determinant of LN enlargement or involvement. Presence of plaques was associated with a significant increase in identification of enlarged or involved LNs in patients with early-stage presentation of MF, which may be important when deciding who to image. Imaging increases the detection rate of stage IIA MF, and identifies rare cases of extensive lymphomatous nodes, upstaging them to advanced-stage IVA2.

Primary cutaneous peripheral T-cell lymphoma, not otherwise specified: results of a multicentre European Organization for Research and Treatment of Cancer (EORTC) cutaneous lymphoma taskforce study on the clinico-pathological and prognostic features

BACKGROUND

Cutaneous peripheral T-cell lymphoma, not otherwise specified (PTL NOS) is an aggressive, but poorly characterized neoplasm.

OBJECTIVES

The European Organization for Research and Treatment of Cancer cutaneous lymphoma taskforce (EORTC CLTF) investigated 33 biopsies of 30 patients with primary cutaneous PTL NOS to analyse their clinical, histological, immunophenotypic features and outcome.

METHODS

Retrospective analysis of clinical data and histopathological features by an expert panel.

RESULTS

Cutaneous PTL NOS manifested clinically either with solitary or disseminated rapidly grown ulcerated tumours or disseminated papulo-nodular lesions. Histologically, a mostly diffuse or nodular infiltrate in the dermis and often extending into the subcutis was found. Epidermotropism was rarely present and only mild and focal. Unusual phenotypes were frequent, e.g. CD3⁺ /CD4^- /CD8^- and CD3⁺ /CD4⁺ /CD8⁺ . Moreover, 18% of the cases exhibited an aberrant expression of the B-cell marker CD20 by the tumour cells. All solitary tumours were located on the limbs and presented a high expression of GATA-3 but this did not correlate with outcome and therefore could not serve as a prognostic factor. The prognosis was shown to be generally poor with 10 of 30 patients (33%) dying of lymphoma within the follow-up of 36 months (mean value; range 3-144). The survival rates were 61% after 3 years (CI, 43-85%) and 54% after 5 years (CI, 36-81%). Small to medium-sized morphology of tumour cells was associated with a better outcome than medium to large or large tumour cells. Age, gender, clinical stage, CD4/CD8 phenotype and GATA-3 expression were not associated with prognosis. Chemotherapy was the most common treatment modality, but surgical excision and/or radiotherapy may represent an appropriate first-line treatment for solitary lesions.

CONCLUSIONS

Cutaneous PTL NOS shows an aggressive course in most patients independent of initial presentation, age and phenotype. Cytomorphology was identified as a prognostic factor. The data indicate a need for more effective treatment modalities in PTL NOS.

Merkel cell carcinoma: A review

Merkel cell carcinoma has been a focus of active scientific investigation in recent years and new information on the topic has emerged. Although uncommon, this primary cutaneous neuroendocrine carcinoma, usually involving the head/neck of elderly individuals, has a poor prognosis. Within the past two decades, an increase in the incidence of the tumor and the discovery of its link to the Merkel cell polyomavirus have focused medical attention on the lesion. The resulting studies have improved our understanding of the biology of the neoplasm and contributed to clinical care. Specifically, two pathogenic subsets of the tumor have come to light, the majority due to Merkel cell polyomavirus and the minority caused by ultraviolet radiation-induced genetic damage. This dichotomy carries prognostic implications favoring the former subset. In addition, having capitalized on the known susceptibility of the tumor to immune influences, investigators have recently discovered its responsiveness to immune checkpoint inhibition. This revelation has constituted a therapeutic milestone at the clinical level. Herein we provide an overview of the topic, outline updates in the field and place an emphasis on dermatopathologic aspects of Merkel cell carcinoma.

Cutaneous lymphohistiocytic infiltrates with foamy macrophages: A novel histopathological clue to Stenotrophomonas maltophilia septicemia

The best-known cutaneous manifestations of septicemia in the skin are the so-called "septic vasculitis" and "septic vasculopathy," which represent two sides of the same pathogenetic process. The spectrum of cutaneous presentations of septicemia is, however, more complex, extending beyond septic vasculitis/vasculopathy. We describe the exceptional histopathological findings of skin lesions associated with Stenotrophomonas maltophilia septicemia, featuring a lymphohistiocytic infiltrate characterized by predominance of foamy macrophages containing granular basophilic material negative for PAS, Gram, Fite, and Grocott. Albeit an uncommon occurrence, S. maltophilia septicemia should be included in the broad differential diagnosis of cutaneous lesions occurring in immunocompromised individuals with worsening general conditions. Awareness of these histopathological findings may facilitate the identification of this insidious infectious agent as a source of nosocomial septicemia.

Blastic plasmacytoid dendritic cell neoplasms: results of an international survey on 398 adult patients

The purpose of this study is to describe the clinical and prognostic features and to evaluate the outcome of different therapeutic approaches among patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) who have been diagnosed and treated in different institutions. A total of 398 patients from 75 centers were included in the study. Treatment consisted of non-Hodgkin lymphoma (NHL)-like regimens in 129 (32.8%) patients and acute leukemia (AL)-like regimens in 113 (23.5%) patients. In 61 (15.5%) and 16 (4.1%) patients, chemotherapy was followed by allogeneic and autologous hematopoietic stem cell transplantation (HSCT), respectively. Twenty-seven (6.9%) patients received radiotherapy, 6 (1.5%) received new agents, and 62 (15.7%) received palliative care. After a median follow-up of 12 months, median overall survival (OS) was 18 months. Patients who received NHL/AL-like regimens, followed by allogeneic HSCT, had the best outcome; median OS was not reached. OS was 65 months for patients who underwent autologous HSCT; 18 months and 14 months, respectively, for those treated with AL-like and NHL-like regimens without consolidation; and 4 months for those receiving palliative care (P < .001). In BPDCN, chemotherapy with lymphoma- or AL-like regimens, followed by transplantation, represents the therapeutic strategy associated with the best outcome. Consolidation with allogeneic HSCT, when feasible, appears superior to autologous HSCT.