Paediatric cutaneous lymphomas including rare subtypes: A 40-year experience at a tertiary referral centre.

BACKGROUND: Primary cutaneous lymphomas are neoplasms of the immune system with a distinct tropism for the skin and an absence of extracutaneous manifestations at the time of diagnosis. Studies focusing on cutaneous lymphomas in children and adolescents remain scarce and often do not encompass the rare subtypes. OBJECTIVES: To address this knowledge gap by describing the clinical, histological and molecular characteristics of a large group of paediatric patients affected by primary cutaneous lymphoma. We also provided the Paediatric Primary Cutaneous Lymphoma Atlas that illustrates the clinicopathological spectrum of observed presentations, in the hope of supporting other physicians in the diagnostic process. METHODS: Retrospective chart review of paediatric patients diagnosed with primary cutaneous lymphomas between 1980 and 2022 at the Paediatric Dermatology Unit of Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan. RESULTS: A total of 101 patients (58 males, 43 females) met the inclusion criteria. The most common subtypes were lymphomatoid papulosis (n = 48) and mycosis fungoides (n = 31). These were followed by primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorders (n = 7), primary cutaneous anaplastic large-cell lymphomas (n = 5), primary cutaneous marginal zone B-cell lymphomas (n = 3), primary cutaneous follicle centre lymphomas (n = 2), subcutaneous panniculitis-like T-cell lymphomas (n = 2), primary cutaneous peripheral T-cell lymphoma not otherwise specified (n = 1), primary cutaneous precursor B-lymphoblastic lymphoma (n = 1) and Sézary syndrome (n = 1). Clinical follow-up data covering a median of 70.8 months (range 1-324) were available for 74 patients, of whom three died due to cutaneous lymphoma. CONCLUSIONS: Our findings shed light on the peculiar aspects and long-term outcomes of paediatric cutaneous lymphomas, particularly emphasizing their distinctive features in comparison to their adult counterparts and exploring the less common subtypes. Further larger-scale studies are warranted to better characterize these entities and to achieve a more rapid and accurate diagnosis.

Whole-genome sequencing of hMPXV1 in five Italian cases confirms the occurrence of the predominant epidemic lineage.

The ongoing outbreak of monkeypox virus (hMPXV1) is the largest recorded in historically nonendemic countries. Genomic surveillance has emerged as a pivotal tool to track the spread and monitor the evolution of viral pathogens. Therefore, to assess the genetic diversity of circulating hMPXV1 in northern Italy in June to July 2022, we sequenced and analyzed five complete genomes of viruses sampled from patients presenting with a typical course of hMPXV1 infection. Phylogenetic analysis confirmed that all five genomes belong to the predominant epidemic lineage (B.1). Inspection of genetic changes and comparison with the reference sequence showed the presence of 12 nucleotide substitutions. Seven are nonsynonymous mutations leading to amino acid changes in six proteins belonging to different functional classes. Moreover, 11 of these 12 nucleotide mutations involve GA>AA or TC>TT replacements, suggesting that host APOBEC3 enzymes are responsible for the generation of substitutions in circulating viruses. Finally, metagenomic analysis evidenced bacterial superinfection (Streptococcus pyogenes) in one patient. Through this study, we contributed to expand the number of complete genomes of viruses circulating in Italy and characterize them as belonging to the predominant outbreak lineage.

T follicular helper phenotype mycosis fungoides associated with acanthosis nigricans.

The association between acanthosis nigricans (AN) and mycosis fungoides (MF) has rarely been described, but it is known that MF may appear as AN-like vegetating and papillomatous plaques in skin folds, or may be associated with paraneoplastic AN. There have also been recent descriptions of a form of "intertriginous MF" that is characterized by skin fold involvement and the expression of T follicular helper (TFH) markers, and that often has an aggressive course. We describe the case of a 48-year-old man affected by MF associated with AN, whose lesions were characterized by a TFH immunophenotype and the expression of the GATA-3 nuclear master regulator that may be related to a TFH-2 subpopulation or possible disease progression.

SARS-CoV-2 Detection by Digital Polymerase Chain Reaction and Immunohistochemistry in Skin Biopsies from 52 Patients with Different COVID-19-Associated Cutaneous Phenotypes.

BACKGROUND: COronaVIrus Disease 19 (COVID-19) is associated with a wide spectrum of skin manifestations, but SARS-CoV-2 RNA in lesional skin has been demonstrated only in few cases. OBJECTIVE: The objective of this study was to demonstrate SARS-CoV-2 presence in skin samples from patients with different COVID-19-related cutaneous phenotypes. METHODS: Demographic and clinical data from 52 patients with COVID-19-associated cutaneous manifestations were collected. Immunohistochemistry and digital PCR (dPCR) were performed in all skin samples. RNA in situ hybridization (ISH) was used to confirm the presence of SARS-CoV-2 RNA. RESULTS: Twenty out of 52 (38%) patients presented SARS-CoV-2 positivity in the skin. Among these, 10/52 (19%) patients tested positive for spike protein on immunohistochemistry, five of whom had also positive testing on dPCR. Of the latter, one tested positive both for ISH and ACE-2 on immunohistochemistry while another one tested positive for nucleocapsid protein. Twelve patients showed positivity only for nucleocapsid protein on immunohistochemistry. CONCLUSIONS: SARS-CoV-2 was detected only in 38% of patients, without any association with a specific cutaneous phenotype, suggesting that the pathophysiology of cutaneous lesions mostly depends on the activation of the immune system. The combination of spike and nucleocapsid immunohistochemistry has higher diagnostic yield than dPCR. Skin persistence of SARS-CoV-2 may depend on timing of skin lesions, viral load, and immune response.

Deregulation of JAK2 signaling underlies primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma.

Primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (pcAECyTCL) is a rare variant of cutaneous T-cell lymphoma with an aggressive clinical course and a very poor prognosis. Until now, neither a systematic characterization of genetic alterations driving pcAECyTCL has been performed, nor effective therapeutic regimes for patients have been defined. Here, we present the first highresolution genetic characterization of pcAECyTCL by using wholegenome and RNA sequencing. Our study provides a comprehensive description of genetic alterations (i.e., genomic rearrangements, copy number alterations and small-scale mutations) with pathogenic relevance in this lymphoma, including events that recurrently impact genes with important roles in the cell cycle, chromatin regulation and the JAKSTAT pathway. In particular, we show that mutually exclusive structural alterations involving JAK2 and SH2B3 predominantly underlie pcAECyTCL. In line with the genomic data, transcriptome analysis uncovered upregulation of the cell cycle, JAK2 signaling, NF-κB signaling and a high inflammatory response in this cancer. Functional studies confirmed oncogenicity of JAK2 fusions identified in pcAECyTCL and their sensitivity to JAK inhibitor treatment. Our findings strongly suggest that overactive JAK2 signaling is a central driver of pcAECyTCL, and consequently, patients with this neoplasm would likely benefit from therapy with JAK2 inhibitors such as Food and Drug Adminstration-approved ruxolitinib.

Array-based CGH of primary cutaneous CD8+ aggressive EPIDERMO-tropic cytotoxic T-cell lymphoma.

Primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (pcAECyTCL) is a rare provisionally categorized cutaneous lymphoma characterized by an aggressive course. Its pathogenesis and molecular mechanisms are still unknown, and only two individual cases have so far been molecularly characterized. The aim of this study was to define the pattern of numerical chromosomal alterations in tumor samples taken from 20 patients with pcAECyTCL at the time of diagnosis by means of array-comparative genomic hybridization (a-CGH). a-CGH detected numerous genomic aberrations in all the patients and, putting these together as a whole, they affected all the chromosomes. However, no specific profile of recurrent copy number alterations (CNAs) was found. Most of the gains involved regions previously described in other aggressive cutaneous lymphomas such as 7q, 8q24.3, and 17q, whereas the most significant CNA was the loss of 9p21.3 (CDKN2A-CDKN2B), which has already been found in a variety of malignant tumors and is associated with aggressive cutaneous T-cell lymphomas. In brief, CGH analysis revealed a large number of CNAs with only few recurring regions that probably do not represent driving events. The genomic instability found in this aggressive variant of cutaneous lymphoma may therefore be a secondary event but, at the time of the diagnosis of pcAECyTCL, the genomic integrity of tumor cells is already compromised.

Extracellular MicroRNA Signature of Human Helper T Cell Subsets in Health and Autoimmunity.

Upon T cell receptor stimulation, CD4+ T helper (Th) lymphocytes release extracellular vesicles (EVs) containing microRNAs. However, no data are available on whether human CD4+ T cell subsets release EVs containing different pattern of microRNAs. The present work aimed at filling this gap by assessing the microRNA content in EVs released upon in vitro T cell receptor stimulation of Th1, Th17, and T regulatory (Treg) cells. Our results indicate that EVs released by Treg cells are significantly different compared with those released by the other subsets. In particular, miR-146a-5p, miR-150-5p, and miR-21-5p are enriched, whereas miR-106a-5p, miR-155-5p, and miR-19a-3p are depleted in Treg-derived EVs. The in vitro identified EV-associated microRNA signature was increased in serum of autoimmune patients with psoriasis and returned to healthy levels upon effective treatment with etanercept, a biological drug targeting the TNF pathway and suppressing inflammation. Moreover, Gene Set Enrichment Analysis showed an over-representation of genes relevant for T cell activation, such as CD40L, IRAK1, IRAK2, STAT1, and c-Myb in the list of validated targets of Treg-derived EV miRNAs. At functional level, Treg-derived (but not Th1/Th17-derived) EVs inhibited CD4+ T cell proliferation and suppressed two relevant targets of miR-146a-5p: STAT1 and IRAK2. In conclusion, our work identified the miRNAs specifically released by different human CD4+ T cell subsets and started to unveil the potential use of their quantity in human serum to mark the pathological elicitation of these cells in vivo and their biological effect in cell to cell communication during the adaptive immune response.

Primary cutaneous acral CD8 positive T-cell lymphoma with extra-cutaneous involvement: A long-standing case with an unexpected progression.

Primary cutaneous acral CD8+ T-cell lymphoma (acral CD8+ TCL) is a new provisional entity characterized by acral skin lesions and an indolent course. We describe an extraordinary case characterized by relapsed nodules with CD8+ cytotoxic infiltrates on the left ear. After 35 years, the skin lesions spread to other acral sites, and a mass with the same histological features as the other skin lesions appeared on the nose. Multiple courses of chemotherapy led to stable disease. Histological examinations carried out at different times showed the gradual transformation of the neoplastic cells, with an increased proliferation index. Genomic analysis revealed losses in the regions harboring the genes involved in cell cycle control. This is the first case of an acral CD8+ TCL with a very long history of indolent nodular lesions progressing to extra-cutaneous sites.

Clinicopathological and molecular study of primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma.

BACKGROUND: Primary cutaneous CD4+ small-/medium-sized pleomorphic T-cell lymphoma (CD4+ PCSM-TCL) is a rare lymphoproliferative disorder with a favorable prognosis. Distinguishing it from other cutaneous lymphomas is often a challenge. METHODS: We retrospectively collected CD4+PCSM-TCL cases from two centers (MD Anderson Cancer Center, USA and University of Milan, Italy) and evaluated their clinicopathological features. Array-comparative genomic hybridization (aCGH) analysis was performed on 11 cases. RESULTS: A total of 62 patients were identified. Single lesions were the most common clinical presentations (79%). Five patients (8%) showed multiple MF-like plaques. All patients' disease had an indolent course. The infiltrate was nodular and diffuse, multinodular or superficial but in all cases, it was characterized by small/medium pleomorphic CD4+/CD279(PD1+) lymphocytes grouped in clusters and 'pseudorosettes' around B-cells. aCGH analysis showed no significant genomic abnormalities. Single lesions were mainly treated with surgical excision (91%) and/or radiotherapy (95%) with low rate of relapse (12%). For multiple lesions, topical steroids, nitrogen mustard and phototherapy were mainly used but the rate of relapse was high (69%). CONCLUSIONS: CD4+PCSM-TCL is characterized by heterogeneous clinical presentations. The arrangement of atypical cells in clusters or pseudorosettes is a useful criterion for diagnosis. The absence of significant genomic alterations is in agreement with its indolent behavior.

Sézary Syndrome in a 17-Year-Old Boy: Clinicopathologic Features and Genomic Profile.

We describe the case of a 17-year-old Hispanic boy who had had erythroderma and diffuse lymphadenopathy for approximately 6 months. A diagnosis of Sézary syndrome was made on the basis of the histologic features of the skin; the presence of the same T-cell clone on the skin, blood, and bone marrow; and the high CD4(+) lymphocyte count with an aberrant phenotype in peripheral blood; bone marrow involvement was also present. The patient was treated with systemic gemcitabine and achieved partial remission.

Whole-exome sequencing is feasible on a fresh-frozen skin sample of intravascular large B cell lymphoma.

Intravascular large B-cell lymphoma (IVLBCL) is a rare aggressive extranodal non-Hodgkin lymphoma. The predominant, if not exclusive, growth of neoplastic cells within the lumina of small-sized vessels represents the hallmark of the disease. Diagnosis is challenging due to the absence of marked lymphadenopathy, the highly heterogeneous clinical presentation, and the rarity of the condition. Clinical presentation is characterized by variable combinations of nonspecific signs and symptoms (such as fever and weight loss), organ-specific focal manifestations due to altered perfusion, and hemophagocytic syndrome. The rarity of this entity and the paucity of neoplastic cells in biopsy samples hamper the study of recurrent molecular abnormalities. The purpose of this study was to explore the feasibility of a different approach to recover a sufficient amount of DNA of acceptable quality to perform next-generation sequencing studies. Here, we report the findings of whole-exome next-generation sequencing performed on a fresh-frozen cutaneous sample of IVLBCL, paired with the patient saliva used as germline DNA. To increase the cancer cell fraction, only the subcutaneous tissue was selected. With this approach, we obtained high-quality DNA and were able to identify oncogenic mutations specific for this entity and recapitulating its post-germinal center origin, even if the tumor fraction was low. Molecular studies performed on fresh-frozen cutaneous sample are feasible in IVLBCL, especially when analysis is restricted to the subcutaneous tissue. Wide adoption of this reproducible and cost-effective approach may foster further studies, which may be of help in supporting diagnosis, providing pathogenetic insights, and guiding treatment decisions.

Twenty-one cases of blastic plasmacytoid dendritic cell neoplasm: focus on biallelic locus 9p21.3 deletion.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive malignancy derived from precursors of plasmacytoid dendritic cells. We analyzed 21 cases with array-based comparative genomic hybridization (aCGH). Complete or partial chromosomal losses largely outnumbered the gains, with common deleted regions involving 9p21.3 (CDKN2A/CDKN2B), 13q13.1-q14.3 (RB1), 12p13.2-p13.1 (CDKN1B), 13q11-q12 (LATS2), and 7p12.2 (IKZF1) regions. CDKN2A/CDKN2B deletion was confirmed by FISH. This scenario argues for disruption of cell cycle at G(1)/S transition, representing a genetic landmark of BPDCN, and possibly contributing to its pathogenesis. Statistical analysis of overall survival in our series highlighted an association of poor outcome with biallelic loss of locus 9p21.3. We suggest that, in the absence of reliable parameters for predicting prognosis in BPDCN other than age, tumor stage, and/or clinical presentation, simple methods, such as FISH for CDKN2A/CDKN2B, could help to identify the most aggressive cases.

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.

Cutaneous extranodal NK/T-cell lymphoma: a clinicopathologic study of 5 patients with array-based comparative genomic hybridization.

Extranodal natural killer/T-cell (ENK/T) lymphoma is a rare neoplasm, subcategorized into ENK/T-nasal (ENK/T-N) and ENK/T-nasal type (ENK/T-NT) lymphomas. ENK/T-NT lymphoma with initial presentation in the skin is known as primary cutaneous ENK/T-NT (PC-ENK/T-NT) lymphoma. The aim of this study was to investigate pathogenesis, genomic alterations, and prognosis of cutaneous ENK/T lymphomas to provide further insights into clinicopathologic features and genetic mechanism of lymphomagenesis. A retrospective case study of 5 white patients affected by ENK/T lymphoma (4 PC-ENK/T-NT and 1 ENK/T-N with cutaneous involvement) was performed. Most of the cases presented with multiple nodules and ulcerations localized on the extremities. A considerable percentage had disease in advanced stage with a 12-month survival rate of 40%. Genomic alterations were detected by array-based comparative genomic hybridization that showed gains of 1q, 7q and loss of 17p in the cases of PC-ENK/T-NT lymphomas and gain of 7q and loss of 9p, 12p, 12q in the case of ENK/T-N lymphoma. In conclusion, ENK/T lymphoma is a very aggressive entity, and, in our cases, the exclusively cutaneous presentation was not associated with a better prognosis. The results of our array comparative genomic hybridization analysis could be useful to better define the different ENK/T lymphoma subgroups with cutaneous involvement.

Primary Cutaneous Gamma-Delta T Cell Lymphomas: A Case Series and Overview of the Literature.

Primary cutaneous gamma-delta T cell lymphomas (PCGDTCLs) are rare and aggressive cutaneous malignancies that have been diagnostically challenging for dermopathologists and clinicians since their first published descriptions in 1991. Since then, the availability of immunostaining for T cell receptors γ and δ in formalin-fixed paraffin-embedded samples has greatly increased our knowledge of the gamma-delta phenotype by showing that it may also be present in the context of indolent entities, such as mycosis fungoides (MFs) and lymphomatoid papulosis, and this has raised questions concerning its diagnostic and prognostic implications. We here describe the histological and clinical differences between the dermo-epidermal and subcutaneous sub-groups of PCGDTCL observed in a cohort of 20 patients attending a single experienced centre, with particular focus on cases with an MF-like presentation, which are still less well defined than those of classic MF.

Immunohistochemical expression and prognostic role of CD10, CD271 and Nestin in primary and recurrent cutaneous melanoma.

BACKGROUND: CD10, CD271 and Nestin, which are proteins associated with tumor-initiating properties and/or progression potential, have not been specifically studied on malignant melanoma (MM) with cutaneous recurrences. METHODS: We evaluated the expression of CD10, CD271 and Nestin in 27 tumor samples from 16 patients. These tumor samples corresponded to 6 primary melanomas which developed 11 ITM and 10 primary melanomas without recurrences at 10-year follow-up from specimens obtained from surgical excisions of patients referred to the Unit of Dermatology, Department of Medical-Surgical and Transplant Physiopathology, University of Milan, between 2006 and 2016. RESULTS: We demonstrated a higher expression of CD271 and Nestin in primary tumors which recurred than control population, Nestin was expressed with significantly higher percentages in primary tumors than recurrences, and CD10 expression was statistically significant correlated with disease-free survival: cases with a lower score recurred lately than cases with higher scores. CONCLUSIONS: Our preliminary results suggested that CD271 and Nestin can be considered early biomarkers for the development of ITM, Nesting can be useful in differentiating primary MM from cutaneous recurrences and CD10 is associated with a rapid disease progression and may be considered a potential prognostic marker.

Cutaneous tricholemmal carcinoma: a 15-year single center experience.

BACKGROUND: Clear cell morphology has been described in several cutaneous neoplasms either as a specific feature of some entities either as a morphological variant in the spectrum, and these two entities are frequently considered together in the differential diagnosis. METHODS: We reviewed our series of cases occurred in our laboratory in order to further quantify the number of cases showing morphological features of tricholemmal differentiation and to investigate other clinical or histological difference. We retrieved 91 cases and, for each of them, all the clinical data regarding age, sex, clinical features, and clinical suspicious were collected, when available. RESULTS: The revision of the specimens concluded with a final diagnosis of tricholemmal carcinoma in 15 cases (17%), all the other cases were thus considered as squamous cell carcinoma with clear cell features. No statistically significant correlations were observed with the demografic or clinicopatholagical parameters such as age, sex or dimensions, but morphological revision highlighted a potentially greater "vertical" growth frequently not matched by a concomitant radial one in tricholemmal carcinoma than in squamous tumors. CONCLUSIONS: The debate upon the diagnostic distinction of these tumors is still ongoing with authors proposing the tricholemmal carcinoma as a variant of a squamous cell carcinoma rather than a distinct entity. Further studies are needed to confirm our data and to evaluate the reproducibility of this feature.