Dermatofibroma is a common dermal nod- ule that is unexplained (Campanacci, 2013). Dermatofibroma is most frequently found in the skin and soft tissues of cats, occasional- ly found in horses and mules, and rarely in other domestic species’ skin, including dogs. Dermatofibroma is usually asymptomatic, but itching and pain are often noted. Derma- tofibroma is the most common of all painful skin tumors (Crisan et al., 2014). The exact mechanism for the development of Derma- tofibroma is unknown. Rather than a reactive tissue change, evidence that Dermatofibroma may be a neoplastic process is demonstrated by its clonal proliferative growth (Chen et al., 2000). The cause of Dermatofibroma is un- known, it was historically attributed to being a reactive response to some traumatic lesion to the skin (e.g. arthropod bite) (Reich et al., 2017). Clonality, by itself, is not necessari- ly synonymous with a neoplastic process; it has been demonstrated in inflammatory con- ditions, including atopic dermatitis, lichen
sclerosis, and psoriasis. Dermatofibroma tu- mor genesis may be due to distorted protein kinase C activity (Płaszczyca et al., 2014).
A seven-year-old female Persian leopard was dead because of accidents a road-kill in Golestan National Park, Iran, in May 2014. Following necropsy, skin mass on the sideline of the right toe was observed. The mass was dissected in necropsy. The resect- ed mass sample was grayish-white in color and measured 2×2×1.5cm, with necrosis at the cut surface (Figure 1). The sample was fixed in 10 % buffered formalin. Serial sections of the formalin-fixed, paraffin-em- bedded sample were produced and serial sections were cut, using a rotary microtome (Leitz, 1512, Germany) at 5 μm. The sam- ples were stained by routine hematoxylin and eosin (HandE) and CD34 immunohis- tochemical staining.