Malignant Pigmented Villonodular Synovitis in the Knee - Report of a Case with Rapid Clinical Progression

Malignant pigmented villonodular synovitis (PVNS) (or malignant giant cell tumor of tendon sheath (GCTTS) is an extremely rare condition defined as a malignant lesion occurring with concomitant or previously documented PVNS at the same site. To date, only less than 20 cases have been reported in English literatures. We report a case of malignant PVNS in the knee in a 56-year-old woman with unpredictable rapid progression. This case raised a caution that when atypical components in specimens of recurrent benign PVNS are detected, even if low-grade or tiny, both pathologists and surgeons should consider the risk of malignant PVNS, which could display aggressive clinical progression

Severe Pulmonary Hypertension Caused by Smoldering Plasma Cell Myeloma: An Autopsy Case of POEMS Syndrome

The POEMS syndrome (coined to refer to polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes) is a rare variant of plasma cell disorders with multiple systemic manifestations. Recently, pulmonary hypertension (PH) has become established as a complication, but pathological studies of this condition are scarce and the detailed pathogenesis remains to be elucidated. We present herein a case of a 49-year-old woman who was diagnosed as having idiopathic PH and was treated in accordance. However, she eventually died of respiratory failure and an autopsy revealed the presence of smoldering plasma cell myeloma and multiple organomegaly in addition to severe PH. The latter was attributed to stenosis and occlusion of the arterioles of the lungs due to marked plasma cell proliferation, quite different from the histology of idiopathic PH. From these findings, together with the clinical details, we concluded that the patient’s PH was a complication of the POEMS syndrome. This case showed a unique pulmonary vascular pathology featuring plasma cell proliferation and it provides clues towards understanding the pathogenesis with this background

Receptor activator of NF-κB ligand induces cell adhesion and integrin α2 expression via NF-κB in head and neck cancers

Cellular interactions with the extracellular matrix play critical roles in tumor progression. We previously reported that receptor activator of NF-κB ligand (RANKL) specifically facilitates head and neck squamous cell carcinoma (HNSCC) progression in vivo. Here, we report a novel role for RANKL in the regulation of cell adhesion. Among the major type I collagen receptors, integrin α2 was significantly upregulated in RANKL-expressing cells, and its knockdown suppressed cell adhesion. The mRNA abundance of integrin α2 positively correlated with that of RANKL in human HNSCC tissues. We also revealed that RANK-NF-κB signaling mediated integrin α2 expression in an autocrine/paracrine manner. Interestingly, the amount of active integrin β1 on the cell surface was increased in RANKL-expressing cells through the upregulation of integrin α2 and endocytosis. Moreover, the RANK-integrin α2 pathway contributed to RANKL-dependent enhanced survival in a collagen gel and inhibited apoptosis in a xenograft model, demonstrating an important role for RANKL-mediated cell adhesion in three-dimensional environments

Animal Model of Mycoplasma pneumoniae Infection Using Germfree Mice

We have attempted to establish a gnotobiotic mouse model monoassociated with Mycoplasma pneumoniae following single or repeated infection to examine the mechanism of pathogenesis following M. pneumoniae infection. M. pneumoniae inoculated into germfree mice colonized equally well at 10(5) CFU/lung in both single infection and repeated infection. In histopathological observation, repeatedly infected mice showed pneumonia with mild infiltration of mononuclear cells and macrophages. Antibody titers against M. pneumoniae rose in the repeatedly infected mice but not in the singly infected mice. The percentage of CD4-positive, CD8-positive, and CD25-positive lymphocytes infiltrated in the lung was increased in the repeatedly infected mice. In contrast, the lymphocyte subset in the spleen was not significantly different among mock-, singly, and repeatedly infected mice. In the study of cytokine productivity of spleen cells, production of interleukin (IL)-4 and IL-10 was significantly increased and that of gamma interferon was remarkably increased in the mice following repeated infection. These results indicate that a gnotobiotic mouse model monoassociated with M. pneumoniae was established and that immune mechanisms might be involved in the pathogenesis in pneumonia following M. pneumoniae infection