Massive Perivillous Fibrin Deposition and Chronic Histiocytic Intervillositis a Complication of SARS-CoV-2 Infection.

An emerging complication of COVID-19 (SARS-CoV-2) infection is reported. A 23-year-old patient presented with high temperature and reduced fetal movements at 25 + 5/40 weeks of gestation. RT-PCR proved maternal COVID-19 infection. Ultrasound examination confirmed intrauterine death. Placenta histology showed necrosis of the villous trophoblast, associated with Chronic Histiocytic Intervillositis (CHI) and Massive Perivillous Fibrin Deposition (MPFD) with up to 90% - of the intervillous spaces being involved. Immunohistochemistry showed CD68 positive histiocytes in the intervillous spaces and the villous trophoblast was positive for the COVID-19 spike protein. RNA scope signal was indicative of the presence of the viral genome and active viral replication in the villous trophoblastic cells, respectively. MPFD is a gradually developing end-stage disease with various etiology, including autoimmune and alloimmune maternal response to antigens expressed at the feto-maternal interface and frequently accompanies chronic alloimmune villitis or histiocytic intervillositis. Covid-19 infection is associated with similar pattern of histological changes of the placenta leading to placental insufficiency and fetal death. This case report supports maternal- fetal vertical transmission of SARS-CoV-2 virus leading to placental insufficiency and fetal demise. MPFD and CHI appear to be the typical placental histology for SARS-CoV-2 virus infection associated fetal demise.

The Pathology of Lymphocytes, Histiocytes, and Immune Mechanisms in Mycobacterium tuberculosis Granulomas.

Granuloma formation is the pathologic hallmark of tuberculosis (TB). Few studies have detailed the exact production of cytokines in human granulomatous inflammation and little is known about accessory molecule expressions in tuberculous granulomas. We aimed to identify some of the components of the immune response in granulomas in HIV-positive and -negative lymph nodes. We investigated the immunohistochemical profiles of CD4+, CD8+, CD68+, Th-17, Forkhead box P3 (FOXP3) cells, accessory molecule expression (human leukocyte antigen [HLA] classes I and II), and selected cytokines (interleukins 2, 4, and 6 and interferon-γ) of various cells, in granulomas within lymph nodes from 10 HIV-negative (-) and 10 HIV-positive (+) cases. CD4+ lymphocyte numbers were retained in HIV- granulomas, whereas CD4+:CD8 + cell were reversed in HIV+ TB granulomas. CD68 stained all histiocytes. Granulomas from the HIV+ group demonstrated a significant increase in FOXP3 cells. Interleukin-2 cytoplasmic expression was similar in both groups. Interferon-gamma (IFN-γ) expression was moderately increased, IL-6 was statistically increased and IL-4 expression was marginally lower in cells from HIV- than HIV+ TB granulomas. Greater numbers of cells expressed IFN-γ and IL-6 than IL-2 and IL-4 in HIV- TB granulomas. This study highlights the varied cytokine production in HIV-positive and -negative TB granulomas and indicates the need to identify localized tissue factors that play a role in mounting an adequate immune response required to halt infection. Although TB mono-infection causes variation in cell marker expression and cytokines in granulomas, alterations in TB and HIV coinfection are greater, pointing toward evolution of microorganism synergism.

Burkitt lymphoma with unusual granulomatous reaction. A case report.

Formation of epithelioid histiocytic cell granulomas has been described in the post in various neoplasms, hematologic malignancies included. Among lymphoproliferative disorders such changes are commonly found in Hodgkin lymphoma and T-cell non-Hodgkin lymphomas (NHL), but are rarely described in B-NHL, like Burkitt lymphoma. This report presents a case of sporadic Burkitt lymphoma accompanied by a sarcoid-like reaction without any clinical, laboratory or histological evidence of microorganisms nor sarcoidosis. Using in situ hybridization and polymerase chain reaction the presence of the Epstein-Barr virus (EBV) was detected in the analyzed lymphoma cells. EBV demonstrated latency I phenotype as defined by the lack of immunohistochemical positivity of latent membrane protein 1 (LMP1). Cytogenetic investigation using fluorescence in situ hybridization uncovered c-MYC mutation and provided indirect indication for the MYC/IgL fusion gene. The lack of EBV positivity in histiocytes indicated the reactive character of the granulomatous reaction in relation to the neoplasm. The role of the granulomatous reaction in the biology and prognosis of Burkitt lymphoma and the function of EBV infection in its development remain to be established.

Subcellular immunolocalization of porcine circovirus type 2 (PCV2) in lymph nodes from pigs with post-weaning multisystemic wasting syndrome (PMWS).

Post-weaning multisystemic wasting syndrome (PMWS) is one of the most significant porcine diseases worldwide. The causative agent is porcine circovirus type 2 (PCV2), the smallest virus known to infect animals. Data related to the structural and ultrastructural aspects of this infectious disease are sparse and there is little knowledge of the subcellular localization of PCV2 and its replication in the tissues of pigs naturally affected by PMWS. The present study describes the cellular localization of PCV2 in the lymph nodes of pigs affected by PMWS by application of immunolabelling techniques for light and transmission electron microscopy (TEM). PCV2 particles were exclusively detected in histiocytes. Ultrastructural alterations including marked dilatation of rough endoplasmic reticulum and swelling of mitochondria were associated with PCV2-labelled intracytoplasmic inclusions (ICIs) with recognizable virions. Within the ICIs icosahedral virus-like particles were specifically labelled with a PCV2 capsid antibody, whereas particles with a granular appearance were not labelled. Colocalization studies with confocal microscopy and double immunolabelling with TEM indicated a close relationship between virus and the mitochondria, suggesting that these organelles may play an important role in the replication of PCV2. The present findings further support the hypothesis that virus replicates within the histiocytes of lymph nodes.

Cytologic diagnosis of hemophagocytic lymphohistiocytosis in ascitic fluid: a case report.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH), also known as macrophage activation syndrome, is a rare, fatal hematopoietic disease. Its cytologic features may be subtle because the abnormal histiocytes may not be recognized if one is not aware of this entity. We report a case of HLH involving the ascitic fluid. CASE REPORT: A 73-year-old man developed weakness, lethargy, decreased appetite and progressive shortness of breath after a cholecystectomy. Physical examination revealed hypotension, tachycardia and chest dullness with decreased breath sounds bilaterally. Radiologic examination revealed bilateral pleural effusions. The patient accumulated fluid in the peritoneal cavity, lungs, retroperitoneum and mediastinum. Bone marrow biopsy showed abundant histiocytes infiltrating the marrow cavity, and many of these histiocytes contained cellular debris. A diagnosis of HLH was therefore made. The abdominal paracentesis specimen contained many similar histiocytes exhibiting erythrophagocytosis and lymphophagocytosis. These abnormal histiocytes were positive for CD68 and negative for AE1/AE3, confirming the diagnosis of HLH. The patient died soon after from disseminated aspergillosis. CONCLUSION: HLH is cytologically characterized by the presence of abnormal histiocytes with ingested cellular debris. In serous effusions they should not be confused with mesothelial cells. Immunohistochemical studies may help confirm the diagnosis.

An association between parvovirus B19 and Kikuchi-Fujimoto disease.

Although Kikuchi-Fujimoto disease (KFD) has a higher prevalence among Asian countries, it is a well-defined entity throughout the world. However, its etiology and pathogenesis remain undetermined. To study whether B19 infection is associated with idiopathic KFD (iKFD), we examined the presence of the viral genome and proteins in paraffin-embedded tissues of lymph nodes retrospectively from 33 iKFD patients and 16 age- and sex-matched control subjects by nested PCR (nPCR), in situ hybridization (ISH), and immunohistochemistry (IHC). B19 was detected in 87.1, 69.7, and 57.6% of iKFD specimens by nPCR, ISH, and IHC, respectively, whereas the virus was positive in only 56.3, 31.3, and 25.0% of control tissues by the respective methods (nPCR: p = 0.029; ISH: p = 0.011; IHC: p = 0.032). The IHC-ISH double-staining assay demonstrated that B19-infected cells were mainly lymphocytes and a small number of histiocytes. These results showed for the first time a high frequency of localized persistence of B19 in lymph nodes from iKFD patients, suggesting that B19 might play an important role in the pathogenesis of iKFD.

Epidemiology and pathologic features of Hodgkin lymphoma.

Hodgkin lymphoma (HL) has unique epidemiologic characteristics. The variation in incidence according to age, sex, race, socioeconomic status, and histologic subtype suggests an etiologic heterogeneity for this tumor. Epidemiologic studies have shown that both genetic and environmental factors play a role in the pathogenesis of HL. HL is one of the Epstein-Barr virus-associated lymphomas, but the oncogenetic mechanism of HL remains to be elucidated. Recent advances in molecular biology have revealed the peculiar nature of the nodular lymphocyte predominant subtype, and as a result this disease is separated from classic types of HL in the new World Health Organization classification. Reed-Sternberg (RS) cells and lymphocytic and/or histiocytic (L&H) cells originate from germinal center B-cells. Loss of the B-cell phenotype due to down-regulation of several B-cell-specific transcription factors is characteristic of RS cells in classic HL.

Cell reservoirs in lymph nodes infected with HIV-1 subtype E differ from subtype B: identification by combined in situ polymerase chain reaction and immunohistochemistry.

In Thailand, the predominant HIV subtype is E, rather than subtype B as in North America and Europe. Subtype E has the ability to replicate in vitro in Langerhans cells. We hypothesized that this cell type might constitute a reservoir for the HIV virus in infected lymph nodes. We examined lymph nodes from 25 HIV-1 subtype E-infected patients to determine the immunophenotype of HIV-1-infected cells, their numbers and their distribution. The presence of HIV was detected either by in situ reverse transcriptase-polymerase chain reaction or immunoperoxidase. Cell identity was determined by double labelling using alkaline phosphatase-based immunohistochemistry. The majority of HIV-infected cells in the lymph nodes were Langerhans cells (CD1a+S100+) and Langerhans-related dendritic cells (p55+S100+). These cells were located in the paracortical areas of lymph nodes, with a few cells scattered at the edges of germinal centers, but were absent from germinal centers themselves, in contrast to the reported distribution of subtype B virus. In addition, multinucleated giant cells were significantly more common in HIV-infected nodes (64%) compared to controls (4%) (P=0.00002). In conclusion, Langerhans histiocytes and related cells are reservoirs for HIV subtype E in lymph nodes. Disrupting the pathway of infection of Langerhans cells and related cells may be a viable strategy to interfere with transmission of HIV subtype E.

Growth characteristics of canine distemper virus in a new cell line CCT cells originated from canine malignant histiocytosis.

Canine distemper virus (CDV) growth and the morphological characterization were examined in a cell line established from a canine malignant histiocytosis (CCT cell line). The susceptibility of the CCT cells to 3 CDV strains, FXNO, YSA-TC and MD-77 was shown by detection of the antigen in the indirect fluorescent assay. After passaging 4 and 9 times through the CCT cells, only FXNO strain could produce the syncytia where demonstrated the antigens. Titers of 9 passaged viruses through the CCT cells showed slightly higher in the CCT cells than those in Vero cells. Morphological characterization of karyorrhexis and specific DNA ladder by extracted DNA electrophoresis indicated apoptosis in the CDV infected CCT cells.

Juvenile xanthogranuloma: case report with immunohistochemical identification of early and late cytomegalovirus antigens.

Juvenile xanthogranuloma (JXG) is a dermatological condition of unknown etiology that rarely affects the oral mucosa. There are conflicting reports suggesting that it may represent a reactive virally-induced lesion associated with cytomegalovirus (CMV) infection. The present paper reports an additional case of oral JXG and discusses its possible association with CMV infection. The biotin-streptavidin system was used to detect early and late CMV antigens. Positive immunolabelling for both antigens was demonstrated in some histiocytes in the lesion. These findings suggest that JXG may be associated with CMV infection.

Detection of Epstein-Barr virus in the L & H cells of nodular lymphocyte predominance Hodgkin's disease: report of a case documented by immunohistochemical, in situ hybridization, and polymerase chain reaction methods.

Although Epstein-Barr virus (EBV) is commonly present in the neoplastic Reed-Sternberg and Hodgkin cells of the mixed cellularity, nodular sclerosis, and lymphocyte depletion types of Hodgkin's disease (HD), EBV is rare in the neoplastic cells of the nodular lymphocyte predominance type of HD, particularly in the United States. We describe a 19-year-old Hispanic man in whom nodular lymphocyte predominance HD involved a cervical lymph node. Epstein-Barr virus was identified in the neoplastic L & H cells by using in situ hybridization for EBV RNA and immunohistochemical staining for EBV latent membrane protein-1. Polymerase chain reaction studies demonstrated the type A strain of EBV. The presence of EBV in this case may be related to drainage of the virus from the oropharynx to the cervical lymph node. The presence of EBV also may be related to this patient's Hispanic ethnic origin.

Histiocytic necrotizing lymphadenitis. A clinico-pathologic study of 45 cases with in situ hybridization for Epstein-Barr virus and hepatitis B virus.

Forty-five cases of histiocytic necrotizing lymphadenitis (HNL) or Kikuchi-Fujimoto disease were reviewed clinico-pathologically and studied for Epstein-Barr virus (EBV) and hepatitis B virus (HBV) by in situ hybridization to assess their causative role. Histologically, the lymph nodes typically showed relatively well defined paracortical lesions composed of large atypical mononuclear cells, histiocytes, and karyorrhectic nuclear debris. Mild to moderate degree of coagulation type necrosis was present in 24 cases. Clinical features did not vary greatly from previously described female preponderance, young age onset, subacute cervical lymphadenopathy, and frequent leukopenia, except for a few cases with recurrent disease over 8-9 years. Serologic tests revealed EBV IgG antibody in one case, HBV surface antibody in 11 cases and HBV surface antigen in 2 cases. In situ hybridization was performed on 41 cases using internal repeat 1 fragment DNA and EBV-coded small RNA (EBER-1) for EBV, and pan-HBV DNA probe for HBV detection, and showed that all cases were negative for EBV or HBV genome. Our results suggest EBV or HBV may not have causative role in the pathogenesis of HNL.

Epstein-Barr virus-associated hemophagocytic syndrome.

A virus-associated hemophagocytic syndrome (VAHS) is a non-neoplastic, generalized histiocytic proliferation with prominent hemophagocytosis associated with a systemic viral infection. Epstein-Barr virus (EBV) is one candidate for this association but serologic and molecular biologic studies have been lacking in many cases. Although VAHS is generally a benign process, EBV-associated hemophagocytic syndrome (EBV-AHS) is often fatal and has a relatively high mortality rate. Therefore, EBV-AHS must be distinguished from VAHS caused by other viruses. Recent evidence indicates that the pathophysiology in EBV-AHS appears to be mediated by the unrestricted release of cytokines produced by the EBV-infected T cells. Clinical and laboratory findings, the differential diagnosis, virology studies, pathophysiology, and treatment in EBV-AHS are reviewed.

The rash of measles is caused by a viral infection in the cells of the skin: a case report.

Measles skin rash was immunohistochemically examined in an effort to detect virus antigen in skin samples taken from a 15-year-old girl with measles. A sectioned specimen obtained by punch biopsy from a 2nd-day skin lesion showed localized parakeratosis and acanthosis with multinucleated giant cells in the epidermis, thickening and cellular edema of epithelia in the hair follicles, and vascular dilation in the papillary plexus. Measles virus antigen was detected by ABC immunoperoxidase in the epidermis, follicular epithelia, and lympho-histiocytic cell infiltrates in the upper of the dermis. This rash deemed to be caused in part by direct viral infection of the epidermal cells.