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Hemophagocytic lymphohistiocytosis (HLH) is a complex, often under-recognized hyperinflammatory immune dysregulation syndrome arising in a diverse range of clinical scenarios and conditions. The accurate and timely diagnosis of HLH is crucial for patient survival, and usually requires a high level of clinical suspicion. The histologic corollary to clinical HLH – hemophagocytosis – is neither necessary or sufficient for the diagnosis of HLH, as it may be seen in a variety of reactive conditions, or may be absent in true HLH. Nevertheless, the finding of hemophagocytosis in specific clinical situations should prompt the consideration of HLH and further testing to exclude the condition. While traditionally described in bone marrow, identification of hemophagocytosis in other tissues, including lymphoid, splenic, liver, or neural tissue, can be an important asset to the overall recognition of HLH. In this review, we discuss the underlying pathophysiology and etiologies of, morphologic aspects hemophagocytosis and its associated histologic findings in different tissues and give a brief overview of diagnostic criteria and clinical evaluation. [ABSTRACT FROM AUTHOR]

The appropriate management of hematology patients depends first on correct diagnoses. Expert review is important in reaching accurate diagnoses. To improve diagnostic accuracy, the Taiwan Society of Pathology and the Taiwan Division of the International Academy of Pathology has been conducting an expert consultation program for general pathologists since 2001. As per this program, we have received a total of 395 cases (406 samples) for review. We found that meaningful diagnostic discrepancies occurred frequently in hematopathology reviews. Ambiguous or nondiagnostic original reports were the major causative factor for the major discrepancy cases, which demonstrates that diagnostic uncertainty is a big problem for referring pathologists. However, the World Health Organization lymphoma classification may be poorly reproducible in countries where extensive use of an ancillary technique is not used by general pathologists. This review is intended to report the misdiagnoses most commonly seen in the hematopathology practice in Taiwan. Awareness of the easily misinterpreted entities helps to achieve the right diagnosis and improve patient care. [Copyright &y& Elsevier]

Abstract: Introduction: Most radiolucent jaw lesions are benign and resolve with proper diagnosis and treatment. However, a small percentage of radiolucent jaw lesions are malignant and more difficult to manage. Methods: A biopsy of the radiolucent jaw lesion associated with swelling after nonsurgical root canal therapy was submitted. Results: The lesion had the combined diagnosis of diffuse large B-cell lymphoma with cystic involvement. The patient has since undergone radiation and chemotherapy treatments. Recall appointments indicate healing of the lesion, and no other areas of lymphoma have been found. Conclusions: The existence of a nonhealing radiolucent jaw lesion emphasizes the importance of an early, definitive diagnosis with biopsy. [Copyright &y& Elsevier]

Summary: In 1994, Chang et al described a novel herpesvirus in tissues from patients with Kaposi sarcoma, referred to as Kaposi sarcoma herpesvirus or human herpesvirus 8. They used a very sophisticated technique of molecular biology to isolate unknown DNA sequences from Kaposi sarcoma lesions, which were not present in normal tissues. It turned out that these sequences corresponded to a previously unrecognized gamma herpesvirus highly homologous to human herpesvirus 4 (Epstein-Barr virus) and to herpesvirus saimiri. Contrary to Epstein-Barr virus, human herpesvirus 8 is not ubiquitous. The seroprevalence of human herpesvirus 8 varies greatly worldwide, with 1% to 10% of people being infected in developed countries and up to 80% of infected individuals in some areas of sub-Saharan and equatorial Africa. Human herpesvirus 8 is associated with a limited spectrum of tumors, mostly observed in immunodeficient individuals with HIV infection. Beside Kaposi sarcoma and multicentric Castleman disease, human herpesvirus 8 is associated with primary effusion lymphoma, but unlike Epstein-Barr virus, human herpesvirus 8 is not involved in epithelial tumors. Different proteins of the virus can be detected in infected cells. Antibodies against the latent nuclear antigen 1 are available in routine pathology and represent a powerful tool to detect the virus in human tissues. Although Epstein-Barr virus is the most frequent causative agent of lymphomas in immunocompromised individuals, a systematic screening of such tumors with specific antibodies reveals that the implication of human herpesvirus 8 infection is probably underestimated. Recent descriptions of non-Hodgkin lymphoma in endemic areas, solid localizations of primary effusion lymphoma, and posttransplantation lymphoproliferations have expanded the spectrum of human herpesvirus 8–related lymphoproliferative disorders. In this review, we will be presenting an overview of the recent concepts regarding human herpesvirus 8 and related disorders. [Copyright &y& Elsevier]

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