Fibroma in a Nine-banded armadillo (Dasypus novemcinctus)

An adult male Nine-banded armadillo (Dasypus nonemcintus) had a large tumour between the first and second phalanges of the right fore-foot. The tumour was of dermal origin, consisted of dense interlacing bundles of collagen, and contained numerous fibroblasts with elongate nuclei and sparse cytoplasm. Mitotic figures were not observed, there was no evidence of lipid accumulation, and there was no metastasis to regional lymph nodes or other tissues. Electron microscopy showed that the major cells of the tumour were fibroblasts. These did not contain nuclear or cytoplasmic inclusions but had dense bodies in the nucleus and there was a conspicuous absence of lysosomes. This lesion was considered to be a benign fibroma of undetermined aetiology.