Paediatric-onset lymphomatoid papulosis: results of a multicentre retrospective cohort study on behalf of the EORTC Cutaneous Lymphoma Tumours Group (CLTG).

BACKGROUND: Lymphomatoid papulosis (LyP) is a rare cutaneous T-cell lymphoproliferative disorder. Comprehensive data on LyP in the paediatric population are scarce. OBJECTIVES: To characterize the epidemiological, clinical, histopathological and prognostic features of paediatric LyP. METHODS: This was a retrospective multicentre international cohort study that included 87 children and adolescents with LyP diagnosed between 1998 and 2022. Patients aged ≤ 18 years at disease onset were included. LyP diagnosis was made in each centre, based on clinicopathological correlation. RESULTS: Eighty-seven patients from 12 centres were included. Mean age at disease onset was 7.0 years (range 3 months-18 years) with a male to female ratio of 2 : 1. Mean time between the onset of the first cutaneous lesions and diagnosis was 1.3 years (range 0-14). Initial misdiagnosis concerned 26% of patients. LyP was most often misdiagnosed as pityriasis lichenoides et varioliformis acuta, insect bites or mollusca contagiosa. Erythematous papules or papulonodules were the most frequent clinical presentation. Pruritus was specifically mentioned in 21% of patients. The main histological subtype was type A in 55% of cases. When analysed, monoclonal T-cell receptor rearrangement was found in 77% of skin biopsies. The overall survival rate was 100%, with follow-up at 5 years available for 33 patients and at 15 years for 8 patients. Associated haematological malignancy (HM) occurred in 10% of cases (n = 7/73), including four patients with mycosis fungoides, one with primary cutaneous anaplastic large cell lymphoma (ALCL), one with systemic ALCL and one with acute myeloid leukaemia. If we compared incidence rates of cancer with the world population aged 0-19 years from 2001 to 2010, we estimated a significantly higher risk of associated malignancy in general, occurring before the age of 19 years (incidence rate ratio 87.49, 95% confidence interval 86.01-88.99). CONCLUSIONS: We report epidemiological data from a large international cohort of children and adolescents with LyP. Overall, the disease prognosis is good, with excellent survival rates for all patients. Owing to an increased risk of associated HM, long-term follow-up should be recommended for patients with LyP.

Lymphomatoid papulosis is a very rare skin condition caused by an abnormal increase in white blood cells (called 'lymphocytes') in the skin. The condition rarely affects children, so most of the scientific data published about this disease focuses on adults. This study involved 12 academic dermatology centres in Europe, the Middle East and North America, and gathered data from about 87 children who presented with symptoms of lymphomatoid papulosis before the age of 19 years. The aim of this study was to better describe this disease in the paediatric population and discuss its treatment options and evolution. We found that the presentation of the disease in children is roughly the same as in adults. Safe and effective treatment options exist. The disease is not life threatening, but it requires investigation by a dermatologist, both to make a careful diagnosis and to monitor it as sometimes associated cancers that originate from blood cells can occur, mostly on the skin.

Molluscum Contagiosum Virus: Biology and Immune Response.

Molluscum contagiosum virus is a poxvirus belonging to the Poxviridae family, which includes Orthopoxvirus, Parapoxvirus, Yantapoxvirus, Molluscipoxvirus, Smallpox virus, Cowpox virus and Monkeypox virus. MCV belongs to the genus Molluscipoxvirus and has a tropism for skin tissue. MCV infects keratinocytes and, after an incubation period of 2 weeks to 6 weeks, causes a breakdown of the skin barrier with the development of papules of variable size depending on the proper functioning of the immune response (both adaptive and acquired). MCV only infects humans and does not cause viraemia. MCV encodes for several inhibitory proteins responsible to circumvent the immune response through different signalling pathways. Individuals who can be infected with MCV are children, immunocompromised individuals such as organ transplant recipients and Human Immunodeficiency Virus (HIV)-infected individuals. Current treatments to manage MCV-induced lesions are different and include the use of immunomodulators, which, however, do not provide an effective response.

The differential expression of toll like receptors and RIG-1 correlates to the severity of infectious diseases.

The toll like receptors (TLRs) and RIG-1 are proteins involved in the initial reaction of the innate immune system to infectious diseases and, thus, can provide much information to the surgical pathologist in terms of the molecular dynamics of the infection. The TLRs (TLR1, 2, 3, 4, 7, 8) and RIG-1 distribution as determined by immunohistochemistry was examined in the following diseases: human papillomavirus (n = 30 including 15 squamous intraepithelial lesions (SIL), 5 cancers, and 10 controls); molluscum contagiosum (n = 8 including 4 controls), SARS-CoV2 (n = 52 including 20 mild, 5 fatal, and 27 controls) and reovirus infection as oncolytic therapy. Mild, regressing infection (molluscum contagiosum, mild SARS-CoV2 and low grade SIL) each showed the same pattern: marked up regulation of at least three of the TLRs/RIG-1 with decreased expression of none compared to the controls. Severe infection (fatal SARS-CoV2, and cervical cancer) each showed marked decrease expression in at least three of the TLRs/RIG-1. We recently documented an equivalent marked decrease expression of the TLRs/RIG-1 in the placenta in fatal in utero infections. The reoviral infected tissues showed an overall pattern of marked increase expression of TLRs/RIG-1, consistent with a strong anti-viral response. Thus, the in situ testing of infectious diseases by a panel of these early infectious disease recognition proteins may allow the surgical pathologist to predict the outcome of the disease which, in turn, may assist in the understanding of the role of the TLRs/RIG-1 in determining the fate of a given infectious process.

Molluscum contagiosum of the corneal limbus in an AIDS patient: a clinicopathological case report.

BACKGROUND: Molluscum contagiosum, a pox virus infection, is likely to occur in the eyelid skin; however, corneal involvements by molluscum lesions are extremely rare. We report a case of molluscum contagiosum arising in the corneal limbus in an untreated AIDS patient, together with anterior segment optical coherence tomography (OCT) findings and histopathology of the excised tumor. CASE PRESENTATION: A 46-year-old man with AIDS was referred to our department for the management of an ocular lesion. Blood tests revealed an extremely low CD4+ T-cell count of 11 cells/µL, being strongly positive for anti-HIV antibody (591.36 S/CO) with a high copy number of HIV RNA (8070.0 × 100 copy/mL). Slit-lamp examination of his right eye showed a white nodule at the lower limbus. Anterior segment OCT findings of the nodule revealed a highly reflective elevated lesion, which was considered to involve the Bowman layer. The nodular lesion was excised from the limbus including the superficial corneal stroma, and then processed for histologic examination. Histopathology of the excised lesion showed acanthotic corneal epithelium containing swollen cells with eosinophilic inclusions known as molluscum bodies. He was diagnosed with molluscum contagiosum. CONCLUSIONS: Anterior segment OCT findings provide useful information for morphological evaluations of and preoperative strategies against molluscum contagiosum.

Molluscum contagiosum with dermoscopic features in an unusual areola and nipple location.

Molluscum contagiosum is a common, contagious viral skin disease that often affects children and adolescents. Involvement of the areola and nipple are rarely reported. Herein we report two young women with molluscum contagiosum on the areola-nipple complex and we discuss the dermoscopic features of the lesions at this unusual site.

Molluscum contagiosum infection with features of primary cutaneous anaplastic large cell lymphoma.

CD30+ T cell pseudolymphomas (CD30+ PSL) are a group of benign inflammatory cutaneous disorders that can develop in settings of viral infections or drug reactions. Owing to their histological similarities to malignant lymphomas, these benign infiltrates are occasionally misdiagnosed as malignant, causing significant concerns for patients and physicians. Herein, we report a patient with CD30+ PSL associated with molluscum contagiosum whose initial biopsy revealed atypical large CD30-expressing cells, leading to a misdiagnosis of primary cutaneous anaplastic large cell lymphoma and referral to our cutaneous lymphoma clinic. We report this case to demonstrate that reactive CD30+ infiltrate associated with molluscum contagiosum can be mistaken for T-cell lymphomas and patients should be reassured in these cases.

Langerhans cell histiocytosis mimicking molluscum contagiosum: A case series.

Langerhans cell histiocytosis (LCH) is a disorder characterized by accumulation of Langerhans-like cells in one or various organs. A correct staging work-up is essential since there are multiorgan presentations with a poor prognosis. We report three patients with LCH skin lesions mimicking molluscum contagiosum in association with both high and low risk organ involvement. This peculiar cutaneous presentation can be a clue for the diagnosis of LCH, a disease with potentially severe systemic involvement.

Molluscum contagiosum arising in a melanocytic congenital nevus.

Molluscum contagiosum within a congenital melanocytic nevus has rarely been reported. We report a 6-year-old child with molluscum contagiosum infection arising within an intermediate melanocytic congenital nevus of the thigh, associated with itching and occasional bleeding. Dermoscopy lead to the correct diagnosis, but histologic confirmation with shave biopsy was performed to reassure the parents and allow mechanical removal of the lesions using curettage.

Molluscum Contagiosum Virus Transcriptome in Abortively Infected Cultured Cells and a Human Skin Lesion.

UNLABELLED: Molluscum contagiosum virus (MOCV), the only circulating human-specific poxvirus, has a worldwide distribution and causes benign skin lesions that may persist for months in young children and severe infections in immunosuppressed adults. Studies of MOCV are restricted by the lack of an efficient animal model or a cell culture replication system. We used next-generation sequencing to analyze and compare polyadenylated RNAs from abortive MOCV infections of several cell lines and a human skin lesion. Viral RNAs were detected for 14 days after MOCV infection of cultured cells; however, there was little change in the RNA species during this time and a similar pattern occurred in the presence of an inhibitor of protein synthesis, indicating a block preventing postreplicative gene expression. Moreover, a considerable number of MOCV RNAs mapped to homologs of orthopoxvirus early genes, but few did so to homologs of intermediate or late genes. The RNAs made during in vitro infections represent a subset of RNAs detected in human skin lesions which mapped to homologs of numerous postreplicative as well as early orthopoxvirus genes. Transfection experiments using fluorescent protein and luciferase reporters demonstrated that vaccinia virus recognized MOCV intermediate and late promoters, indicating similar gene regulation. The specific recognition of the intermediate promoter in MOCV-infected cells provided evidence for the synthesis of intermediate transcription factors, which are products of early genes, but not for late transcription factors. Transcriptome sequencing (RNA-seq) and reporter gene assays may be useful for testing engineered cell lines and conditions that ultimately could provide an in vitro replication system. IMPORTANCE: The inability to propagate molluscum contagiosum virus, which causes benign skin lesions in young children and more extensive infections in immunosuppressed adults, has constrained our understanding of the biology of this human-specific virus. In the present study, we characterized the RNAs synthesized in abortively infected cultured cells and a human skin lesion by next-generation sequencing. These studies provided an initial transcription map of the MOCV genome, suggested temporal regulation of gene expression, and indicated that the in vitro replication block occurs prior to intermediate and late gene expression. RNA-seq and reporter assays, as described here, may help to further evaluate MOCV gene expression and define conditions that could enable MOCV replication in vitro.

Handheld reflectance confocal microscopy for the diagnosis of molluscum contagiosum: Histopathology and dermoscopy correlation.

Handheld reflectance confocal microscopy may represent an adjunctive, fast, non-invasive tool for the diagnosis of molluscum contagiosum, revealing microscopic details closely related to histopathology, as demonstrated by this study evaluating 19 molluscum lesions in 11 patients. It permits the rapid examination of one or multiple skin lesions in real time and it is perfectly suitable for children.

Primitive follicular induction in molluscum contagiosum.

BACKGROUND: Molluscum contagiosum (MC) is the commonest human poxvirus infection. Follicular induction has rarely been observed in the epidermis surrounding lesions of MC. A virus-induced localized proliferation of germinative/stem cells of the folliculosebaceous-apocrine unit has been suggested as the underlying cause, however few reports of this peculiar phenomenon exist in the literature and the mechanisms involved in this proliferation require further study. METHODS: We prospectively collected MC cases showing multifocal areas of primitive follicular induction involving the adjacent undersurface epidermis. Immunohistochemical expression of BerEP4, PHLDA1 and cytokeratin 20 (CK20) was evaluated in the basaloid germs surrounding the lesions. For PHLDA1, we used epidermal melanocytes as a positive internal control. For BerEP4, we employed a basal cell carcinoma (BCC) and for CK20, colon as positive external controls. An incubation without the primary antibody functioned as an external negative control. RESULTS: All the cases studied showed an intense positive staining of the basaloid buds with BerEP4 and weaker stain for PHLDA1. CK20 showed the presence of scattered Merkel cells within the induced epidermal basaloid proliferations favoring their reactive origin. DISCUSSION: The pathogenetic mechanisms behind the development of these microscopic features and the link between follicular induction and poxvirus infection are explored. Awareness of this unusual phenomenon by dermatopathologists will be helpful in avoiding a misdiagnosis of a superficial BCC in such cases. CONCLUSIONS: BerEP4 and PHLDA1 were consistently expressed in the areas of primitive follicular induction surrounding lesions of MC. CK 20 stained the Merkel cells present in the basaloid buds. All these findings support the reactive origin of this phenomenon, which we believe is most probably viral-induced.

Woronoff Ring: A Novel Manifestation of Molluscum Contagiosum.

Woronoff ring has been mostly discussed as a phenomenon in psoriasis, especially during therapy. It has also been reported in a few other conditions unrelated to psoriasis; however, the association of Woronoff ring has not been reported in immunocompetent, healthy, and untreated patients with molluscum contagiosum who have no apparent systemic illness. The authors report a case series of Woronoff ring seen in untreated immunocompetent patients with molluscum contagiosum involving different age groups.

Molluscum Contagiosum Infection Involving a Benign Epidermoid Cyst in an Immunocompetent Patient.

A 78-year-old man presented with a round- to oval-shaped nodule on his right eyebrow. The lesion first developed 5 years ago as a small solitary white nodule and subsequently enlarged over the past 2 years. His medical history was unremarkable. Clinical examination revealed a 2-cm round to oval dome-shaped yellowish nodule with a dimple on the top center (Figure 1). No similar lesions were found elsewhere. With a clinical suspicion of sebaceous carcinoma, an excision of the lesion was performed under local anesthesia. The histopathologic analysis showed an epidermal cyst containing molluscum bodies along the keratin inside the cyst (Figure 2). With these findings, the diagnosis of molluscum contagiosum (MC) infection into an epidermoid cyst was made. Neither recurrence nor new similar lesions were observed at follow-up.

Molluscum contagiosum of the eyelid: case report in a man receiving methotrexate and literature review of molluscum contagiosum in patients who are immunosuppressed secondary to methotrexate or HIV infection.

BACKGROUND: Molluscum contagiosum is a benign viral infection of the skin. Lesions typically present as dome-shaped, flesh-colored, umbilicated papules that range in size from 1 to 5 millimeters in diameter. They are usually asymptomatic, but can become tender or pruritic. Children and immunocompromised adults, including individuals being treated with immunosuppressive drugs, are most susceptible to infection. Single or multiple lesions most commonly appear on the extremities, face, genitals, and trunk. However, albeit rarely, molluscum contagiosum may also develop at other sites, including the eyelids. PURPOSE: We describe the clinical and pathologic findings of a man who developed molluscum contagiosum of the eyelid while receiving methotrexate. We also review the characteristics of other patients with molluscum contagiosum acquired either during treatment with methotrexate or associated with human immunodeficiency virus (HIV) infection and summarize the unusual sites of presentation for the viral lesions in these individuals. MATERIALS AND METHODS: The features of a man receiving methotrexate who developed molluscum contagiosum of the eyelid are presented. Using PubMed, the following terms were searched and relevant citations assessed: adalimumab, contagiosum, Enbrel, etanercept, Humira, infliximab, methotrexate, molluscum, Remicade, TNF alpha, and tumor necrosis factor alpha. In addition, the literature on methotrexate treatment and molluscum contagiosum is reviewed. RESULTS:  Several small papules were observed on the eyelid of a 24-year-old man who had been receiving methotrexate and adalimumab (Humira) for the treatment of Crohn disease. The lesions were removed by shave biopsy. Microscopic examination revealed epidermal hyperplasia composed of keratinocytes filled with large eosinophilic intracytoplasmic inclusions. Based on correlation of the clinical presentation and histopathologic findings, a diagnosis of molluscum contagiosum was established. The patient applied mupirocin 2% ointment to the biopsy sites, which subsequently healed without complication or recurrence. CONCLUSION: Molluscum contagiosum is a benign viral papular eruption that frequently affects children and immunocompromised adults. Patients treated with immunosuppressive agents, such as methotrexate, have a heightened risk of developing molluscum contagiosum lesions. It remains to be determined whether adjunct therapy with a tumor necrosis factor alpha inhibitor increasesthe risk of this viral infection. Diagnosis can usually be established by clinical presentation, although a biopsy is sometimesrequired to exclude other conditions. Molluscum contagiosum is generally self-limiting and often resolves spontaneously within18 months. However, topical (cantharidin) or locally destructive (curettage, cryotherapy, and/or laser) therapy may be indic tedfor patients who are concerned about persistent lesions and for children who are particularly susceptible to autoinoculation.