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.

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 presenting as periorbital abscess in immunocompetent children.

Molluscum contagiosum presenting as a periorbital region abscess is unusual. The virus generally causes a self-limiting localized disease in children. Presentation as an abscess has been reported mainly in immunocompromised patients. We performed a retrospective study of ten children treated for Molluscum contagiosum infection presenting as periorbital abscess. Data investigated included age, immunocompetence, systemic antibiotic treatment, clinical findings, and histopathology. All children were immunocompetent. Bacterial cultures taken in six of the ten children were positive in two. Seven patients received oral antibiotics before presentation but required IV antibiotics on admission. One patient received IV antibiotics only. All antibiotic treatment had very limited effect. Two patients had no antibiotic treatment. CT imaging in one case where orbital cellulitis was suspected showed no significant intraorbital findings with anterior involvement only. Nine out of ten children had surgery and intra-operative cryotherapy at our center with immediate improvement and recovery. One child whose parents initially refused surgical excision had initial limited clinical improvement of periorbital swelling with antibiotics. However, the lesions were excised shortly following discharge from our hospital at another medical center with a complete cure. Molluscum is a cause of periorbital abscess in immunocompetent children which should be part of the differential diagnosis in periorbital/adnexal infection. Antibiotic treatment has a limited effect, and the abscess is most likely a virally triggered reaction. Surgical excision and intra-operative cryotherapy are curative of the disease in our experience.

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.

Eyelid molluscum contagiosum lesion in a pediatric patient treated with topical nail polish.

Molluscum contagiosum causes umbilicated periocular lesions, which commonly affect children. Topical clear nail polish for treatment of molluscum has been reported anecdotally, but there are few reports in the medical literature. We report the case of an eyelid molluscum lesion in an 8-year-old girl that resolved with 4 topical applications of nail polish over 6 weeks.

Epidemiologic Differences and Management of Eyelid Lesions in the Pediatric Population.

PURPOSE: To report the relative incidence of excised pediatric eyelid lesions and describe the correlation between the clinical and pathology diagnosis. METHODS: This was a retrospective analysis of 137 consecutive pathology-confirmed eyelid lesions excised at a U.S. quaternary children's hospital system. Chalazion was excluded from this study. RESULTS: Benign non-cystic epithelial lesions comprised 48.2% of all excised lesions, followed by mesenchymal (14.6%) and cystic (10.2%) lesions. The most common lesions were molluscum contagiosum (21.9%) and verruca vulgaris (19.0%). Hispanic White race represented 62.0% of cases, followed by non-Hispanic White (23.3%) and Black (8.8%). There were no malignant lesions. A specific preoperative clinical diagnosis was attempted in 70.1% of cases. Of these, 60.4% had a matching histopathology. CONCLUSIONS: The authors report a higher proportion of molluscum contagiosum and verruca vulgaris when compared to the literature; these differences may suggest geographic variance, management preference, or a general increase in incidence. Correlation with pathology showed the clinical diagnosis of eyelid lesions can be challenging even for ophthalmologists. However, malignancy in pediatric eyelid lesions is rare and submission for histopathology may be safely omitted, except in cases with atypical features or suspicion for syndromic disease. The decision for surgery should be methodically approached and take into consideration the most likely diagnosis, natural history of the disease, sociopsychological impact, anesthesia risk, and resource burden. [J Pediatr Ophthalmol Strabismus. 2022;59(6):405-409.].

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.

Melanocytic marker Melan-A detects molluscum contagiosum bodies.

Melan-A is one of the most commonly used immunohistochemical assays (IHC) in dermatopathology laboratories to detect the presence and outline the distribution of melanocytes. It is a cytoplasmic stain that detects a melanocyte-specific cytoplasmic protein involved in the formation of stage II melanosomes. Clinically, Melan-A is primarily used to detect and confirm melanocytic tumors although it is also positively expressed in adrenal cortical tumors and sex cord stromal tumors. We found that Melan-A also detected and highlighted Henderson-Patterson bodies of molluscum poxvirus. To determine if other melanocytic markers detect molluscum contagiosum bodies, S-100, HMB-45, MITF, and SOX-10 were also tested. In 15 tested molluscum cases, Melan-A stains were positive in all cases, whereas the other tested melanocytic markers were negative. Our results confirm that Melan-A is very sensitive in detecting molluscum contagiosum bodies and could be clinically useful to supplement the hematoxylin and eosin (H&E) in cases that are very inflamed or only have limited biopsy material.

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.