Roles of Vascular Smooth Muscle Cells in Atherosclerotic Calcification

The accumulation of calcium in atherosclerotic plaques is a prominent feature of advanced atherosclerosis, and it has a strong positive correlation with the total burden of atherosclerosis. Atherosclerotic calcification usually appears first at the necrotic core, indicating that cell death and inflammatory processes are involved in calcification. During atherosclerotic inflammation, various cell types, such as vascular smooth muscle cells, nascent resident pericytes, circulating stem cells, or adventitial cells, have been assumed to differentiate into osteoblastic cells, which lead to vascular calcification. Among these cell types, vascular smooth muscle cells are considered a major contributor to osteochondrogenic cells in the atherosclerotic milieu. In this review, we summarize the molecular mechanisms underlying the osteochondrogenic switch of vascular smooth muscle cells in atherosclerotic plaques.

Splenic myxoid liposarcoma in a dog

A 7-year-old Maltese was presented to a veterinary clinic for a history of anorexia, soft feces, and anemia. During abdominal sonography and computed tomography imaging, splenic mass was suspected. Laparotomy revealed the bloody ascites, and the enlarged spleen containing a large spherical mass. Microscopically, the splenic parenchyma was replaced by neoplastic cells with cytoplasmic vacuolation and abundant myxoid matrix. Cellular vacuolation and myxoid matrix were positive to Oil-Red-O and Alcian-blue stains. The neoplastic cells were positive to vimentin on immunohistochemistry. The case was diagnosed as myxoid liposarcoma. Based on a poor prognosis, the dog was euthanized three weeks after splenectomy.

Carcinoid tumor of gallbladder in a dog

A 7-year-old female mixed-breed dog was presented to a veterinary clinic for pyometra. During abdominal ultrasonography, an abnormal finding was noted in the gallbladder. A cholecystectomy was performed. Grossly, the gallbladder wall was thickened with a polypoid nodular projection into the lumen. Microscopically, the polyp consisted of a solid sheet of round to polygonal-shaped cells that formed small packets with fibrovascular septa. The neoplastic cells contained abundant cytoplasmic eosinophilic granules. Immunohistochemically, the neoplastic cells were positive to chromogranin A and neuron-specific enolase, whereas they were negative to vimentin and cytokeratin. This case was diagnosed as a primary gallbladder carcinoid tumor.

Amyloidosis in a Whooper swan (Cygnus cygnus)

Two Whooper swan (Cygnus cygnus) died after suffering from pododermatitis, lethargy, and ataxia; necropsy was performed. Grossly, the liver was swollen and firm. The kidney and spleen were also enlarged and a pale tan color. On histopathologic examination with Congo red staining, amyloidosis was noted in liver, spleen, and kidney. In addition, marked osseous metaplasia was present in the liver. Based on these results, systemic amyloidosis involving liver, spleen, and kidney with osseous metaplasia in the liver was diagnosed. Study results indicate that an inflammatory reaction associated with pododermatitis had a role in the amyloidosis in this particular case.