Desmoplastic fibroblastoma (Collagenous fibroma) in an African lion

Desmoplastic fibroblastoma (DF) is a rare, benign, slowly growing, soft tissue tumor which originated from fibroblast. Although this type tumor has been occasionally reported in human beings, there was case report that was diagnosed as the DF in animal species. This report describes a case of DF that developed on the left flank of an 8-year-old female African lion. The mass was gradually enlarged for 5~6 months and the size was 25 × 16 × 8 cm³. Surgical excision of the mass was carried out. The mass was relatively hypocellular and showed proliferation of spindle and stellate shaped cells embedded in a fibromyxoid to densely fibrotic collagenous stroma. Six months after performing a surgical excision, no sign of any tumor recurrence or metastasis was observed.