Cutaneous peripheral nerve sheath tumors in 15 dogs

Abstract

: Peripheral nerve sheath tumors (PNSTs) are heterogeneous tumor groups of peripheral nerves that originate from either Schwann cells or modified Schwann cells, fibroblasts, or perineural cells. In this study, signalment and clinical data such as tumor location and size were evaluated for 15 cases of PNSTs collected from local animal hospitals. The mean age of dogs with malignant PNST was higher than that of dogs with benign PNST. Additionally, the male to female ratio in dogs with PNST was 1 : 4. In dogs with PNST, the primary sites of involvement were the hindlimb, forelimb, around the mammary glands, the neck, and the abdomen. Histiopathologic examination revealed that eight PNSTs were benign and seven were malignant. The tumor cells were composed of loosely to densely arranged interlacing bundles and wavy spindle cells arranged in short bundles, palisading, and whirling. High mitotic figures, local invasion, multifocal necrosis and atypical multinucleated giant cells were observed in malignant PNST cases. All PNSTs showed immunoreactivity for vimentin and S-100. However, only 93.3% and 73.3% were immunoreactive for NSE and GFAP, respectively. Overall, these results indicated that immunohistochemical markers such as vimentin, S-100 and NSE could help confirm the diagnosis of canine PNSTs.

Reclassification of 21 Presumptive Canine Peripheral Nerve Sheath Tumors (PNST) Using a Literature-Based Immunohistochemical Panel

“…Several authors suggest that the presence of nerve fi bers within the tumor may be a useful diagnostic indicator. Nevertheless, it is generally accepted that occasional small nerves may be seen in subcutaneous spindle cell tumors and that they are not necessarily related to the tumor itself [1,4,13,14,18]. Therefore, the true incidence of canine PNST and their biologic behavior are yet to be determined, due to poorly established diagnostic criteria.…”

“…Although plenty of different antibodies have been tested in the past fi fteen years to help the identifi cation of canine PNSTs [9,[12][13][14], no specifi c immunohistochemical marker has been identifi ed because of the heterogeneous data that emerged from these studies. For this reason a wide panel of reagents is generally used.…”

“…In feline and equine PNSTs this marker has been proven to be useful in the diagnosis [23,24]. However, S-100 immunoreactivity in canine MPNST may be unrewarding, likely because these neoplasms can be composed of various cell types other than Schwann cells, including perineural cells, or perineural or endoneural fi broblasts [12][13][14]. In our case series, tumor cells positive to S-100 were observed only in one case, possibly due to either a low PNST incidence or a poor sensitivity of this marker.…”

“…Negative controls were obtained by omitting the primary antibody. Tumors were defi ned as positive in the presence of immunolabeling in more than 10% of neoplastic cells according to Ko et al (2014) [14].…”

“…In particular, S-100, oligodendrocyte transcription factor 2 (Olig2), glial fi brillary acidic protein (GFAP), neuron specifi c enolase (NSE) and nerve growth factor receptor (NGFR) were suggested as PNST markers. Moreover, calponin, desmin and alpha-smooth muscle actin (α-SMA) have been proposed as PWT markers [9,[11][12][13][14]. However, the results of such studies were poorly standardized and no defi nitive diagnostic criteria were established.…”