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Merkel cell polyomavirus (MCPyV) monoclonally integrates into genomes of approximately 80% of Merkel cell carcinomas (MCCs) and undergoes mutation. We previously demonstrated statistically significant differences in tumor cell morphology and biology between MCPyV-positive and MCPyV-negative MCCs. We reassessed the usefulness of our morphologic criteria in differentiating MCPyV-negative and MCPyV-positive MCCs for practical diagnosis. Two trainees and 4 pathologists challenged estimations (5-point confidence scale) of MCPyV infection in MCCs using hematoxylin and eosin-stained slides of 43 new MCC cases and 2 morphologic criteria: (1) nuclear polymorphism is higher and cytoplasm is more abundant in MCPyV-negative MCC cells, and (2) MCC combined with squamous cell carcinoma is defined as MCPyV negative, regardless of tumor cell morphology of MCC. Subsequently, immunohistochemistry for MCPyV large T antigen and polymerase chain reaction for MCPyV DNA yielded concordant results (MCPyV positivity was 30/43 and 32/43, respectively) for 41 (96%) of 43 cases. The mean accuracy, sensitivity, and specificity of the trainees and pathologists were 92.4% ± 1.5% and 81.5% ± 11.0%, 95.6% ± 6.2% and 90.2% ± 8.3%, and 83.3% ± 11.8% and 74.6% ± 14.1%, respectively. Values of the areas under the curve were 0.80 to 0.95, indicating good informative scores. Using our morphologic criteria, observers can predict the absence of MCPyV infection and diagnose MCPyV-negative MCCs with poor prognosis. Unexpectedly, the performance of trainees was superior to that of pathologists, implying that our morphologic criteria are useful even for practitioners having little experience. Our morphologic criteria will provide pathologists with convenient and reliable hallmarks for accurate MCC diagnosis.

Objectives: To clarify characteristics on rabbit in vivo infection with type 2 EBV nuclear antigen (EBNA-2)-deleted Epstein-Barr virus (P3HR-1-EBV) and compare infectious efficacy of P3HR-1-EBV with previously reported prototype type 1 EBV from B95-8. Methods: Twelve Japanese White rabbits were inoculated with P3HR-1-EBV via intranasal or intravenous routes and autopsied on day 70–84. Results: In only 2 of 12 P3HR-1-EBV-inoculated rabbits, EBV-DNA was detected in peripheral blood mononuclear cells (PBMCs). BamHI M rightward reading frame (BMRF)-1, EBNA-1 and BamHI Z leftward reading frame (BZLF)-1-mRNA were intermittently expressed in PBMCs. In 1 infected rabbit with continuous detection of EBV-DNA in PBMCs, many EBER-1-positive lymphocytes were observed in germinal centers and/or marginal zones in some follicles of the appendix, and for the first time a lymphocyte with EBER-1 expression infiltrating in the squamous cell layer of the tonsils was found. The other rabbit with a transient detection of EBV-DNA in PBMCs had no EBER-1-positive lymphocytes in the tissues examined. Few EBER-1-positive lymphocytes were detected in some rabbits without detection of EBV-DNA in PBMCs. Conclusions: P3HR-1-EBV showed less efficient infection in rabbits than EBV from the B95-8 cell line. However, a P3HR-1-EBV-inoculated animal model is meaningful because this is the first study of EBNA-2 function on in vivo EBV infection and it demonstrated the in vivo infectivity with lytic-type infection by EBNA-2-deleted EBV.

It has recently been shown that approximately 80% of Merkel cell carcinomas harbor a novel polyomavirus named Merkel cell polyomavirus (MCPyV). MCPyV has been detected in human tissue samples. However, detailed distribution of MCPyV in non-neoplastic Japanese human tissues remains unclear. To address this, we used single or real-time quantitative polymerase chain reaction (PCR) for 41 autopsy cases. PCR revealed MCPyV-DNA in non-neoplastic samples: total, 29/41 (71%); adult, 29/39 (74%); fetus or infant, 0/2; men, 24/28 (86%); women, 5/13 (38%); total human tissues, 66/572 (12%); skin, 8/15 (53%); adrenal gland, 9/33 (27%), and other 16 organs (4–25%). This study first reported the presence of MCPyV-DNA in non-neoplastic tissues of thyroid gland, adrenal gland, spleen, bone marrow, stomach, gallbladder, pancreas, heart, and aorta. PCR revealed that viral load ranged from 0.00026 to 0.22 in all MCPyV-positive tissues compared with Merkel cell carcinoma samples. These detailed PCR data showed higher prevalence of MCPyV infection in Japanese men than women (p = 0.004) and broad distribution of MCPyV with low viral load in more non-neoplastic human tissues than in the previous reports. These data provide valuable insights for further studies of MCPyV infection and MCPyV-related diseases.

Merkel cell polyomavirus is a novel polyomavirus that is monoclonally integrated into genomes of up to 80% of human Merkel cell carcinomas. Merkel cell polyomavirus-positive Merkel cell carcinomas showed less metastatic tendency and better prognosis according to some reports, whereas others disagree. In this study, we analyzed clinicopathological characteristics of 20 Merkel cell polyomavirus-positive and 6 Merkel cell polyomavirus-negative Merkel cell carcinoma cases, in which we already reported the association of Merkel cell polyomavirus infection with statistically significant morphological differences. Immunohistochemical expressions of cell cycle-related proteins, mutations of the TP53 tumor-suppressor gene (exons 4-9) and p14ARF promoter methylation status as well as detailed clinical data were analyzed and compared between Merkel cell polyomavirus-positive and Merkel cell polyomavirus-negative cases. Merkel cell polyomavirus-positive Merkel cell carcinomas showed better prognosis with one spontaneous regression case and significantly higher expression of retinoblastoma protein (P = .0003) and less p53 expression (P = .0005) compared to Merkel cell polyomavirus-negative Merkel cell carcinomas. No significant differences were found in expressions of p63, MDM2, p14ARF or MIB-1 index, and p14ARF promoter methylation status. Interestingly, frequency of TP53 non-ultraviolet signature mutation was significantly higher in Merkel cell polyomavirus-negative Merkel cell carcinomas than in Merkel cell polyomavirus-positive Merkel cell carcinomas (P = .036), whereas no significant difference was detected in TP53 ultraviolet signature mutations between two groups. These results suggest that Merkel cell polyomavirus-positive and -negative Merkel cell carcinomas likely develop through different tumorigenic pathways and that the presence or absence of Merkel cell polyomavirus in the tumor is still an important factor that affects survival in patients with Merkel cell carcinoma.

ejd.2011.1534 Auteur(s) : Ayako Ito1 ayama813@grape.med.tottori-u.ac.jp, Yuichi Yoshida1, Hiromi Higaki-Mori1, Tessin Watanabe1, Kazue Nakanaga2, Norihisa Ishii2, Osamu Yamamoto1 1 Division of Dermatology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago 683-8503, Japan 2 Leprosy Research Center, National Institute of Infectious Diseases, Tokyo, Japan Mycobacterium (M.) scrofulaceum is a slow-growing, non-tuberculous mycobacterium that is widely distributed in nature and is isolated [...]

ejd.2011.1345 Auteur(s) : Hiromi Higaki-Mori higaki.h@med.tottori-un.ac.jp, Tessin Watanabe, Masahisa Shindo, Yuichi Yoshida, Osamu Yamamoto Division of Dermatology, Department of Medicine of Sensory and Motor Organs, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago 683-8503, Japan We herein describe a case of chemical burn by excrement after accidental ingestion of kerosene. An 84-year-old Japanese woman with slight dementia was referred to our clinic for evaluation of erythema with [...]