Extensive Perivillous Fibrin and Intervillous Histiocytosis in a SARS-CoV-2 Infected Placenta From an Uninfected Newborn: A Case Report Including Immunohistochemical Profiling.

Placental infection by SARS-CoV-2 with various pathologic alterations reported. Inflammatory findings, such as extensive perivillous fibrin deposition and intervillous histiocytosis, have been postulated as risk factors for fetal infection by SARS-CoV-2. We describe the placental findings in a case of a 31-year-old mother with SARS-CoV-2 infection who delivered a preterm female neonate who tested negative for SAR-CoV2 infection. Placental examination demonstrated a small for gestational age placenta with extensive intervillous histiocytosis, syncytiotrophoblast karyorrhexis, and diffuse intervillous fibrin deposition. Immunohistochemical staining demonstrated infection of the syncytiotrophoblasts by SARS-CoV-2 inversely related to the presence of intervillous histiocytes and fibrin deposition. Our case demonstrates that despite extensive placental pathology, no fetal transmission of SARS-CoV-2 occurred, as well as postulates a relationship between placental infection, inflammation, and fibrin deposition.

Multicentric histiocytosis related to avian leukosis virus subgroup J (ALV-J)-infection in meat-type local chickens.

Gross lesions characterized by swollen livers and spleens accompanied by diffuse white miliary spots, which resembled those of Marek's disease, were detected in two flocks of local meat-type chickens at a Japanese poultry processing plant in June and August 2010. The microscopic examinations revealed proliferative foci consisting of spindle or polymorphic cells in the interstitium of livers, splenic follicles and the interstitium of kidneys. These cells were positive immunohistochemically with Iba1 antibody, indicating they were histiocytic cells. Some of them contained antigens of avian leukosis virus (ALV) by immunohistochemistry,and the env gene of ALV subgroup J was detected from the spleens by polymerase chain reaction (PCR). Phylogenetic analysis of the PCR product indicated that the env gene might be descended from the American ADOL-7501 strain of ALV-J. These results suggest that the swollen livers and spleens of the meat-type chickens may come from histiocytic proliferation caused by ALV-J infection.

Association of West Nile virus with lymphohistiocytic proliferative cutaneous lesions in American alligators (Alligator mississippiensis) detected by RT-PCR.

West Nile virus (WNV) is known to affect captive populations of alligators and, in some instances, cause significant mortalities. Alligators have been shown to amplify the virus, serve as a reservoir host, and even represent a source of infection for humans. This study describes a cutaneous manifestation of WNV in captive-reared American alligators (Alligator mississippiensis), previously described as lymphohistiocytic proliferative syndrome of alligators (LPSA), based on the findings of gross examination, histopathologic evaluation, WNV antibody testing, and WNV reverse transcriptase polymerase chain reaction (RT-PCR). Forty alligators with LPSA and 41 controls were examined. There was a significant difference (P = 0.01(-21)) in the WNV serostatus between the treatment group (100%) and the control group (0%, 95% CI: 0-7.3%). In the treatment group, 97.5% (39/40) (95% CI: 92.7-102.3%) of the LPSA skin lesions were positive for WNV via RT-PCR. Of the skin sections within the treatment group that had no LPSA lesions, 7.5% (3/40) (95% CI: 0-15.7%) were positive for WNV. In the control group, all of the skin samples were negative for WNV (41/41) (0%; 95% CI: 0-7.3%). The LPSA skin lesions were significantly more likely to be WNV positive by RT-PCR when compared to control animals (P = 0.07(-20)) and normal skin sections from affected animals (P = 0.08(-16)). There was no significant difference in the WNV RT-PCR results between control animals and normal skin sections from affected animals (P = 0.24). These findings suggest that LPSA is a cutaneous manifestation of WNV in alligators.

Detection of Akabane viral antigens in spontaneous lymphohistiocytic encephalomyelitis in cattle.

A 5-month-old Japanese black bull calf and twenty-seven 1-27-day-old calves exhibiting neurological signs between August and October 1998 were examined. The bull calf exhibited rapid breathing, fever, hypersensitivity, and ataxia and was euthanized 4 days after the onset of symptoms. The 27 calves primarily exhibited ataxia, and 15 had arthrogryposis. Histological examination of the bull calf revealed perivascular infiltraction by mononuclear cells, diffuse to multifocal gliosis, and neuronal necrosis in the brain and spinal cord. Multiple malacic foci were found in the midbrain in 5 cases. In contrast, in the 15 calves necropsied in October, there were fewer inflammatory changes, but there was neuronal cell loss in the ventral horn and a decrease in myelinated axons in the lateral and ventral funiculi. Immunohistochemical examination using a rabbit antiserum against Akabane virus strain OBE-1 revealed a large amount of viral antigen in the degenerating neurons and glial cells of the bull calf, mainly in the spinal gray matter. Small amounts of viral antigen in swollen axons and a few glial cells were found in 5 of 27 calves. Thirteen of the 27 calves had high neutralization antibody titers against the Akabane virus, whereas there was no significant antibody titer in most of the calves necropsied during August. The present study revealed that viral antigen detection was very useful for the diagnosis of Akabane diseases in the 5-month-old bull calf that was suspected to be infected postnatally, while it had limited usefulness in the other young calves.

Cytophagic histiocytic panniculitis and subcutaneous panniculitis-like T-cell lymphoma: report of 7 cases.

BACKGROUND: Cytophagic histiocytic panniculitis (CHP) is a rare subtype of panniculitis that usually follows a fatal course, with a terminal hemophagocytic syndrome. Recent reports on a subset of peripheral T-cell lymphoma named subcutaneous panniculitis-like T-cell lymphoma (SPTL) raised the question about the relationship between these entities. OBSERVATIONS: We describe 7 patients in the study: 1 with fatal CHP, 4 with SPTL, and 2 with long-term CHP. The 5 patients with fatal CHP and SPTL died of complications of hemophagocytic syndrome, with a disease duration ranging from 8 to 74 months. The other 2 patients were still alive 6 and 41 years after disease onset. Immunohistochemical results proved that 2 of the SPTL cases were type alpha/beta and expressed the cytotoxic/suppressor antigen CD8, while the other 2 were type gamma/delta and were positive for the natural killer-associated antigen CD56. In these 4 cases, molecular biology studies by polymerase chain reaction detected T-cell receptor gamma gene rearrangement, indicating a clonal process. In contrast, in the 2 patients who had long-term CHP, the polymerase chain reaction results failed to disclose clonality. In the subject with fatal CHP, genotypic analysis was not performed. CONCLUSION: Our observations suggest that CHP and SPTL may span a clinicopathologic spectrum in which there is a natural disease progression from CHP to SPTL.

Kikuchi disease (histiocytic necrotizing lymphadenitis) in association with HTLV1.

We report a 25-year-old male with fever, generalized lymphadenopathy and an erythematosus maculo-papular eruption affecting face and upper body. A diagnosis of Kikuchi disease (necrotizing histiocytic lymphadenitis) was made on lymph node histology. The patient was found to be positive for the human T-cell leukaemia lymphoma virus (HTLV1). Kikuchi disease has been reported in association with infections such as Epstein-Barr virus (EBV), herpes (HHV6) and toxoplasmosis, but to our knowledge this is the first case of Kikuchi disease associated with HTLV1.