Histiocytic Sarcoma and Bilateral Facial Vein Thrombosis in a Siberian Hamster (Phodopus sungorus).

A 21-mo-old, male Siberian hamster (Phodopus sungorus) presented with left-sided facial swelling, proptosis of the left eye, and blepharospasm of the right eye. The hamster had been used only for breeding. Because of the poor prognosis, the hamster was euthanized without additional diagnostic assays or treatments. Routine gross pathologic evaluation demonstrated exophthalmos and presumptive hyphema of the left eye, bilateral facial edema, freely movable nodules within the mesentery, white foci within the liver, and a large mass effacing the cranial pole of the right kidney. On histologic evaluation, the mesenteric nodules and liver foci expressed histiocytic marker CD163 and thus were diagnosed as sites of histiocytic sarcoma, whereas the kidney mass was a well-differentiated renal cell carcinoma. The facial swelling resulted from bilateral, chronic, severe, branching thrombi in many facial veins. Additional age-related histopathologic findings were observed in other organs, including diffuse glomerulopathy, nesidioblastosis (pancreatic islet neoformation), and multiple foci of severe cartilage degeneration in the axial skeleton. To our knowledge, this report provides the first description of histiocytic sarcoma in a Siberian hamster.

The alarmin HMGB-1 influences healing outcomes in fetal skin wounds.

In mice, cutaneous wounds generated early in development (embryonic day 15, E15) heal scarlessly, while wounds generated late in gestation (embryonic day 18, E18) heal with scar formation. Even though both types of wounds are generated in the same sterile uterine environment, scarless fetal wounds heal without inflammation, but a strong inflammatory response is observed in scar-forming fetal wounds. We hypothesized that altered release of alarmins, endogenous molecules that trigger inflammation in response to damage, may be responsible for the age-related changes in inflammation and healing outcomes in fetal skin. The purpose of this study was to determine whether the alarmin high-mobility group box-1 (HMGB-1) is involved in fetal wound repair. Immunohistochemical analysis showed that in unwounded skin, E18 keratinocytes expressed higher levels of HMGB-1 compared with E15 keratinocytes. After injury, HMGB-1 was released to a greater extent from keratinocytes at the margin of scar-forming E18 wounds, compared with scarless E15 wounds. Furthermore, instead of healing scarlessly, E15 wounds healed with scars when treated with HMGB-1. HMGB-1-injected wounds also had more fibroblasts, blood vessels, and macrophages compared with control wounds. Together, these data suggest that extracellular HMGB-1 levels influence the quality of healing in cutaneous wounds.