Merkel cell polyomavirus and Langerhans cell neoplasm

Oncolytic viruses as emerging therapy against cancers including Oncovirus-induced cancers

There are several human viruses with known potential for causing cancers including, Hepatitis B virus, Hepatitis C virus, Epstein-Barr virus, Kaposi's sarcoma herpesvirus, Human T-cell lymphotropic virus, Human papillomavirus, and Merkel cell polyomavirus. Cancer is the second leading cause of death that affects humans worldwide, especially in developing countries. Surgery, chemotherapy, and radiotherapy can cure about 60% of humans with cancer but recurrent and metastatic diseases remain a major reason for death. In recent years, understanding the molecular characteristics of cancer cells has led to the improvement of therapeutic strategies using novel emerging therapies. Oncolytic viruses with the potential of lysing cancer cells defined the field of oncolytic virology, hence becoming a biotechnology tool rather than just a cause of disease. This study mainly focused on targeting cell proliferation and death pathways in human tumor-inducing viruses by developing innovative therapies for cancer patients based on the natural oncolytic properties of reovirus. To kill tumor cells efficiently and reduce the chance of recurrence both the direct ability of reovirus infection to lyse the tumor cells and the stimulation of a potent host immune response are applied. Hence, bioengineered stem cells can be used as smart carriers to improve the efficacy of oncolytic reovirus and safety profiles.

The Role of Histone Post-Translational Modifications in Merkel Cell Carcinoma

Merkel Cell Carcinoma (MCC) is a rare but highly aggressive form of non–melanoma skin cancer whose 5-year survival rate is 63%. Merkel cell polyomavirus (MCPyV), a small DNA tumor virus, is the etiological agent of MCC. Although representing a small proportion of MCC cases, MCPyV-negative MCCs have also been identified. The role of epigenetic mechanisms, including histone post-translational modifications (PTMs) in MCC, have been only partially determined. This review aims to describe the most recent progress on PTMs and their regulative factors in the context of MCC onset/development, providing an overview of current findings on both MCC subtypes. An outline of current knowledge on the potential employment of PTMs and related factors as diagnostic and prognostic markers, as well as novel treatment strategies targeting the reversibility of PTMs for MCC therapy is provided. Recent research shows that PTMs are emerging as important epigenetic players involved in MCC onset/development, and therefore may show a potential clinical significance. Deeper and integrated knowledge of currently known PTM dysregulations is of paramount importance in order to understand the molecular basis of MCC and improve the diagnosis, prognosis, and therapeutic options for this deadly tumor.

Epstein-Barr Virus-Positive Langerhans Cell Sarcoma: Is There a Link? A Case Report

Langerhans cell sarcoma (LCS) is an extremely rare, malignant neoplasm that originates from Langerhans cells (LCs). Fewer than 70 cases have been reported in the English-language literature. LCS typically involves multiple organs, including the skin, lymph nodes, lungs, bone, bone marrow, liver, spleen, and soft tissues. Several etiological factors for LCS have been proposed, including immunosuppression, virus infection, and prior hematological disease. We report a rare case of LCS with Epstein-Barr virus (EBV) infection; bilateral cervical giant cysts were the initial manifestation. To our knowledge, this is the first report of LCS with EBV infection. The case information was complete, and the relevant literature was reviewed to gain insight into LCS. The case raises new questions on the oncogenic character of EBV.

Bone lesions of Langerhans cell histiocytosis triggered by trauma in children

BACKGROUND

Bone lesions of Langerhans cell histiocytosis (LCH) may be triggered by trauma.

METHODS

The characteristics of pediatric patients in the JLSG-02 study cohort who developed a bone lesion at the trauma site at diagnosis of LCH were analyzed retrospectively.

RESULTS

Of the 261 pediatric patients with LCH, 12 (4.6%), of median age 4.9 years, had trauma-triggered bone LCH lesions at diagnosis, making them significantly older than the remaining patients (P = 0.006). Trauma sites included the craniofacial regions in 10 patients and the lumbar spine and pelvis in one patient each. At the time of trauma, six patients had a bump at the site, whereas none had extradural hematomas or bone fractures. The median time from trauma to onset was 4 weeks. Of these 12 patients, three had isolated bone (IB) disease; four had multifocal bone (MFB) disease, including the bone lesion at the trauma site; and five had multisystem disease, including four with lesions in neighboring tissue and one with polyuria (posterior pituitary lesion) more than 1 year before the trauma-triggered bone lesion. Treatment responses were good in all 12 patients and none died, but relapses were observed in two patients, one each with IB and MFB disease.

CONCLUSIONS

About 5% of pediatric patients with LCH developed new trauma-triggered bone lesions at a relatively old age. These lesions can manifest as IB, or, in patients with underlying LCH diseases, as MFB or multisystem. Good clinical outcomes were observed in these patients.

Sending mixed signals: polyomavirus entry and trafficking

Polyomaviruses are mostly non-pathogenic, yet some can cause human disease especially under conditions of immunosuppression, including JC, BK, and Merkel cell polyomaviruses. Direct interactions between viruses and the host early during infection dictate the outcome of disease, many of which remain enigmatic. However, significant work in recent years has contributed to our understanding of how this virus family establishes an infection, largely due to advances made for animal polyomaviruses murine and SV40. Here we summarize the major findings that have contributed to our understanding of polyomavirus entry, trafficking, disassembly, signaling, and immune evasion during the infectious process and highlight major unknowns in these processes that are open areas of study.

A mutation in POLR3E impairs antiviral immune response and RNA polymerase III

RNA polymerase (Pol) III has a noncanonical role of viral DNA sensing in the innate immune system. This polymerase transcribes viral genomes to produce RNAs that lead to induction of type I interferons (IFNs). However, the genetic and functional links of Pol III to innate immunity in humans remain largely unknown. Here, we describe a rare homozygous mutation (D40H) in the POLR3E gene, coding for a protein subunit of Pol III, in a child with recurrent and systemic viral infections and Langerhans cell histiocytosis. Fibroblasts derived from the patient exhibit impaired induction of type I IFN and increased susceptibility to human cytomegalovirus (HCMV) infection. Cultured cell lines infected with HCMV show induction of POLR3E expression. However, induction is not restricted to DNA virus, as sindbis virus, an RNA virus, enhances the expression of this protein. Likewise, foreign nonviral DNA elevates the steady-state level of POLR3E and elicits promoter-dependent and -independent transcription by Pol III. Remarkably, the molecular mechanism underlying the D40H mutation of POLR3E involves the assembly of defective initiation complexes of Pol III. Our study links mutated POLR3E and Pol III to an innate immune deficiency state in humans.

Oral manifestations of Langerhans cell histiocytosis with unusual histomorphologic features

Langerhans cell histiocytosis (LCH) is a bone marrow-derived immature myeloid dendritic cell proliferative disorder with diverse clinical manifestations commonly involves bone, skin, lymph node and lung. Oral involvement is uncommon. Intraoral lesions can be the first sign of either a localized LCH or clinically undiagnosed systemic LCH, predates systemic manifestations of LCH, or an early indicator of recurrence in known cases. Clinically, it can be mistaken for primary oral and dental inflammatory, infectious and neoplastic lesions. Histologically, diagnostic challenges may arise because of the nature of oral and dental specimens, different tissue reaction patterns and variations in histomorphology of LCH. We performed a retrospective review study over 10 years. We searched for diagnosed cases of LCH. We retrieved and reviewed cases of LCH with oral involvement. We found 54 cases of LCH, four (7.4%) with oral involvement. The age range was between 1 and 27 years with an average age of 13.7 years. They were males. They were clinically confused with abscess, cysts, infection, granulation tissue and other neoplastic lesions. Histologically, they showed different histopathologic features including different patterns of necrosis, granulomas, allergic-like inflammation, superimposed infection, stomatitis, cyst and sinus formation, foreign body giant cell reaction, and foci mimicking lymphomas and metastasis. Certain cytologic features were helpful hints. In doubtful cases, immunohistochemistry helped confirm the diagnosis. Because of the multiple fragmented nature of oral specimens with different tissue reaction patterns, the diagnostic Langerhans cells may be missed or misinterpreted. Oral LCH may be confused with infectious, inflammatory, benign and malignant neoplastic lesions because of its variable clinical presentations and its heterogeneous histomorphologic features. Pathologists have an important role in guiding clinicians to the correct diagnosis and patients' management. They should be familiar with the different histomorphologic patterns to avoid pitfalls. Attention to certain morphologic features and immunohistochemistry should help resolve challenging cases.

Incidence, Clinical Features, and Outcomes of Langerhans Cell Sarcoma in the United States

BACKGROUND

Limited knowledge exists on the incidence, treatment patterns, and long-term outcomes of Langerhans cell sarcoma (LCS) in the United States.

PATIENTS AND METHODS

We performed a retrospective study of LCS patients diagnosed between 2001 and 2014 using the Surveillance, Epidemiology, and End Results (SEER) and National Cancer Data Base (NCDB) databases. Incidence was calculated from SEER, and treatment patterns and outcomes were calculated from NCDB.

RESULTS

A total of 25 and 52 cases of LCS were reported to SEER and NCDB, respectively. The overall incidence of the disease was 0.2 per 10,000,000 and did not differ by race (P = .56) or sex (P = .33). The median age at diagnosis was 62 (range, 19-90) years. Of the 52 patients from NCDB, 20 (39%) received chemotherapy as first-line therapy, 24 (46%) received surgery, and 15 (29%) received radiotherapy. The 1-year overall survival (OS) rate was 62%, and the median OS was 19 months. After censoring the patients with bone marrow and reticuloendothelial system involvement, no significant difference in OS was noted between the patients who were managed with or without surgery (P = .75). Postsurgical radiation or chemotherapy were not associated with improvement in median OS (P = .25). Patients who were managed with radiotherapy had a better OS compared to those who received no radiotherapy (P = .03).

CONCLUSION

This dual-national registry study shows that LCS is extremely rare and has a poor prognosis. Radiotherapy may offer a survival advantage to patients with locoregional disease without bone marrow and reticuloendothelial system involvement.