Cytomorphometry of canine cutaneous histiocytoma

Abstract

Abstract A morphometric analysis of tumoral Langerhans cells and activated macrophages was conducted using canine cutaneous tumors (65 cases of canine cutaneous histiocytoma and 7 cases of pyogranuloma). The histiocytic origin of the tumor cells was confirmed using immunohistochemistry. The parameters of the morphometric analysis included cellular and nuclear size and shape and the nuclear: cytoplasmic ratio; the variability of these features was calculated separately for each tumor. The canine cutaneous histiocytoma group was divided into four stages of regression depending on the intensity of the lymphocytic infiltration. Statistical analysis revealed that the anisocytosis, anisokaryosis and cellular pleomorphism of tumoral Langerhans cells increased, while the cellular circularity and nuclear:cytoplasmic ratio decreased with tumor regression. Activated macrophages of the pyogranuloma were significantly larger, and had larger nuclei, than tumoral Langerhans cells. Furthermore, these activated macrophages showed greater anisocytosis and anisokaryosis and a lower nuclear: cytoplasmic ratio than tumoral Langerhans cells in the first stages of tumor regression. These results indicate that tumoral Langerhans cells undergo morphologic changes during the regression of canine cutaneous histiocytoma, reflecting their maturation and differentiation. Morphometry can be a useful method for distinguishing activated macrophages from tumoral Langerhans cells.