A novel cerebral microangiopathy with endothelial cell atypia and multifocal white matter lesions: a direct mycoplasmal infection?

Large Multinucleated Variant Endothelial Cells (MVECs) in Allograft Kidney Microvasculature: A Biopsy Series

There are few published studies examining cytomorphologic alterations in endothelial cells in human tissue. One fascinating but largely unexplored endothelial morphologic variant is large multinucleated variant endothelial cells (MVECs). To our knowledge, there are no published reports of MVECs identified in the kidney. Here, we present a case series of 4 kidney biopsies from allograft kidneys whose microvasculature contained MVECs. Electron microscopy confirmed the endothelial identity in all cases. A broad immunohistochemical panel used in 1 case was also confirmatory of an endothelial cell origin. All cases occurred in the setting of chronic, active, antibody-mediated rejection, and alternative etiologies, such as viral infections, were excluded. Two patients were positive for concurrent donor-specific antibodies, and 3 of the 4 cases occurred in second kidney allografts. We speculate that MVECs are a rare or often overlooked finding often confused for megakaryocytes and may be associated with chronic endothelial cell injury in the setting of chronic antibody-mediated rejection.

A preliminary study on the potential of Mycoplasma pneumoniae to induce dyskaryotic change in respiratory epithelium in adult community-acquired pneumonia

Background:

This study aimed to explore the cellular morphology of respiratory epithelium in Mycoplasma pneumonia (MpP) patients.

Materials and Methods:

The cast-off cell morphological findings from bronchoscopic brushings in MpP and community-acquired pneumonia (CAP) caused by typical pathogens were reviewed.

Results:

Compared with the CAP group, cellular dysplasia in respiratory tract epithelial brushings was significantly greater in MpP patients (P = 0.033).

Conclusion:

Unique biological characteristics and mechanisms of pathogenesis of Mycoplasma pneumoniae (Mp) may result in dyskaryotic changes in respiratory epithelium in adult MpP.

Classification of Extrapulmonary Manifestations Due to Mycoplasma pneumoniae Infection on the Basis of Possible Pathogenesis

The list of extrapulmonary manifestations due to Mycoplasma pneumoniae infection can be classified according to the following three possible mechanisms derived from the established biological activity of M. pneumoniae; (1) a direct type in which the bacterium is present at the site of inflammation and local inflammatory cytokines induced by the bacterium play an important role (2) an indirect type in which the bacterium is not present at the site of inflammation and immune modulations, such as autoimmunity or formation of immune complexes, play an important role, and (3) a vascular occlusion type in which obstruction of blood flow induced either directly or indirectly by the bacterium plays an important role. Recent studies concerning extrapulmonary manifestations have prompted the author to upgrade the list, including cardiac and aortic thrombi as cardiovascular manifestations; erythema nodosum, cutaneous leukocytoclastic vasculitis, and subcorneal pustular dermatosis as dermatological manifestations; acute cerebellar ataxia, opsoclonus-myoclonus syndrome, and thalamic necrosis as neurological manifestations; pulmonary embolism as a respiratory system manifestation; and renal artery embolism as a urogenital tract manifestation. Continuing nosological confusion on M. pneumoniae–induced mucositis (without skin lesions), which may be called M. pneumoniae-associated mucositis or M. pneumoniae-induced rash and mucositis separately from Stevens-Johnson syndrome, is argued in the dermatological manifestations. Serological methods are recommended for diagnosis because pneumonia or respiratory symptoms are often minimal or even absent in extrapulmonary manifestations due to M. pneumoniae infection. Concomitant use of immunomodulators, such as corticosteroids or immunoglobulins with antibiotics effective against M. pneumoniae, can be considered as treatment modalities for most severe cases, such as encephalitis. Further studies would be necessary to construct a comprehensive therapeutic strategy, covering microbiology (antibiotics), immunology (immunomodulators), and hematology (anticoagulants). The possible influence of the emergence of macrolide-resistant M. pneumoniae on extrapulmonary manifestations, which can be considered of limited clinical threat in Japan where the resistant rate has currently decreased, is discussed on the basis of unique biological characteristics of M. pneumoniae, the smallest self-replicating organism.

Mycoplasmal panencephalitis: a neuropathologic documentation

Mycoplasmas, particularly Mycoplasma pneumoniae, have been implicated as causative agents in a large variety of central nervous system diseases, especially acute childhood encephalitis. Postulated pathomechanisms for mycoplasma-mediated neurological disease have included: direct infection, autoimmunity, and vascular occlusion. Neuropathologic data are meager and are reviewed. We report a 3-year-old boy, who developed signs and symptoms of encephalitis 7 days after the onset of fever with cough and death 5 days later. At autopsy, he displayed diffuse vasogenic edema and perivascular to infiltrative inflammatory cells, the latter most prominent in gray matter of brainstem and amygdala. The predominant cell was the CD68-positive macrophage, followed by the T-lymphocyte. Cells immunolabeled with a polyclonal antibody to M. pneumoniae included perivascular to parenchymal macrophages/microglia, occasional oligodendrocytes, and neurons, particularly in brainstem. Affected neurons varied from morphologically normal to profoundly degenerate and necrotic. Ultrastructural study of the inferior olive confirmed the presence of 260-600 nm cell-wall-free microorganisms, consistent with mycoplasma, in perivascular cells and neurons. Foci of acute disseminated encephalomyelitis also were rarely identified. This case report confirms the postulated role of direct infection of brain by mycoplasma in acute childhood encephalitis, but also reveals a virus-like infection of central neurons. The pathogenesis of acute childhood encephalitis due to mycoplasma seems to be multifactorial.

JC Virus Leuko-Encephalopathy in Reduced Intensity Conditioning Cord Blood Transplant Recipient with a Review of the Literature

We report here the case of progressive multifocal leukoencephalopathy (PML) related to human polyomavirus JC (JCV) infection after an allogeneic transplantation with umbilical cord blood cells in 59-year-old woman with follicular Non Hodgkin lymphoma. She presented with dysphagia and weakness; magnetic resonance imaging demonstrated marked signal abnormality in the sub-cortical white matter of the left frontal lobe and in the posterior limb of the right internal capsule. Polymerase chain reaction (PCR) analysis of the cerebrospinal fluid (CSF) was positive for John Cunningham (JC) virus. JC viral DNA in the CSF was positive, establishing the diagnosis of PML. Brain biopsy was not done. Extensive investigations for other viral infections seen in immuno-compromised patients were negative. The patient's neurologic deficits rapidly increased throughout her hospital stay, and she died one month after the diagnosis. These findings could have practical implications and demonstrate that in patients presenting neurological symptoms and radiological signs after UCBT, the JCV encephalitis must be early suspected.

Mycoplasmal cerebral vasculopathy in a lymphoma patient: presumptive evidence of Mycoplasma pneumoniae microvascular endothelial cell invasion in a brain biopsy

A 73-year-old man had episodic encephalopathy, ataxia and neuropathy. Symptoms largely resolved but adenopathy later lead to the diagnosis of a low-grade follicular lymphoma. The neurological symptoms soon recurred with new pontine calcifications identified by computed tomography. Brain biopsy revealed microvascular endothelial cell nuclear changes. Electron microscopy identified small polymorphic bacteria without a cell wall and with terminal and attachment organelles within endothelial cells and clustered in some microvascular lumina. Immunostaining was positive for Mycoplasma pneumoniae and convalescent serum enzyme immunoassay was positive for M. pneumoniae IgG. The patient again recovered and he was neurologically stable 33 months after the initial episode. The ultrastructural findings of the bacterial cells are distinctive of some mycoplasmal species when compared to other small bacteria. Mycoplasma-like organisms are reported in four autopsied patients who had chronic encephalopathy, movement disorders, and some of the same light- and electron-microscopic findings in the brain as our patient. Direct neuroinvasion by Mycoplasma species has been suggested, while anatomic observations in our patient and in the four autopsy cases show microvascular invasion but not parenchymal invasion. Most mycoplasmal encephalitis may be immune-mediated. The frequency of neurovascular invasion is not known. It may be rare and it may persist.