II Tumours of the Mouse, pp. It was housed in an environmentally controlled room and was fed a certified rodent chow ad libitum. The liver was enlarged and contained multiple raised 0.5-1.0 cm diameter nodules in all lobes. The uterus contained a tan 1.0-2.0 cm diameter mass in the left uterine horn. Diffusely, liver sinusoids are infiltrated by round to fusiform neoplastic cells that randomly from irregular sheets and efface the parenchyma.
Cells have large round to oval nuclei and abundant eosinophilic cytoplasm.
Research indicates that the cells are derived from histiocytes. Histiocytic sarcomas are rare before 12 months of age, and are more common in females. Other organs that may be affected include spleen, lymph node, bone marrow, lung, kidney and ovaries. Metastasis to the lung is common when there is liver involvement. HS are uncommon in mice younger than one year of age, and have been associated with viral etiologies.