Immunohistochemical Staining Characteristics of Canine Gastrointestinal Stromal Tumors

Abstract

Sections from 35 formalin-fixed, paraffin-embedded, canine gastrointestinal stromal tumors consisting of 14 leiomyomas (five stomach, three small intestine, two colon, four rectum), 18 leiomyosarcomas (one stomach, five small intestine, nine cecum, three rectum), two undifferentiated sarcomas (two stomach), and one neurofibrosarcoma (small intestine) were examined for the expression of vimentin, S-100 protein, alpha-smooth muscle actin, and desmin via immunoperoxidase methodology using an avidin-biotin complex technique. The leiomyomas were 4/14 (29%) vimentin-positive, 3/14 (21%) S-100 protein-positive, 10/14 (71%) alpha-smooth muscle actin-positive and 13/14 (93%) desmin-positive. Leiomyosarcomas were 18/18 (100%) vimentin-positive, 11/18 (61%) S-100 protein-positive, 9/18 (50%) a-smooth muscle actin-positive, and 15/18 (83%) desmin-positive. The undifferentiated sarcomas were 2/2 (100%) vimentin-positive, 2/2 (100%) S-100 protein-positive, 1/2 (50%) alpha-smooth muscle actin-positive, and 0/2 (0%) desmin-positive. The neurofibrosarcoma was vimentin and S-100 protein-positive and alpha-smooth muscle actin- and desmin-negative. Thirty-one of thirty-five (89%) of all neoplasms demonstrated reactivity for either desmin and/or alpha-smooth muscle actin. S-100 protein reactivity occurred in 17/35 (49%) of all specimens. Lack of desmin and alpha-smooth muscle actin reactivity occurred in 4/35 (11%) of all specimens, all of which were vimentin-positive. The immunohistochemical results indicate that the majority of canine gastrointestinal stromal tumors (GIST) with light microscopic features of smooth muscle cells have immunohistochemical staining patterns supporting smooth muscle differentiation. Vimentin reactivity correlated with a light microscopic diagnosis of malignancy. The lack of smooth muscle cell markers in some tumors and the high percentage of cases positive for S-100 protein may suggest a more complex histogenesis or differentiation for subgroups of these tumors.

Comparison of Tyrosinase-related Protein-2, S-100, and Melan A Immunoreactivity in Canine Amelanotic Melanomas

“…However, we also detected S-100 in several nonmelanoma tumor types that have been shown to be S-100 positive in other studies. 4,6,9 All three schwannomas we tested were S-100 positive (Fig. 7).…”

“…Our results for S-100 immunohistochemistry in melanomas, schwannomas, and GISTs were similar to those reported previously. 4,6,12 In one study, S-100 was detected immunohistochemically in 75% of pigmented melanomas and 90% of amelanotic melanomas of dogs. 5 All seven cell lines established from canine melanomas also expressed S-100 protein.…”

“…S-100 antibodies react with a variety of normal tissues and tumors. 4,6,9,10,12 The sensitivity and specificity of other antibodies against melanocytic markers (HMB-45, NKI/C3, HMSA-1 and HMSA-5, and Melan A) have been tested in canine melanomas. Among them, Melan A has proven the most successful, although different investigators have reported varying success using this antibody.…”

Three Cases of Canine Gastrointestinal Stromal Tumors with Multiple Differentiations and c-kit-Expression

“…Human GISTs are reported to arise in the esophagus, anus, and even omentum, mesen-and retro-peritoneum besides the gastrointestinal wall [9,17,23]. In animals, tumors resembling to human GISTs have been reported in rhesus macaques [1], dogs [10], and horses [2,3]. The present study describes morphological, immunohistochemical, and ultrastructural features of GISTs with c-kit expression in 3 dogs.…”

“…However, the tumor could be considered as muscular type because of the wide range specificity of the neural markers. As previously mentioned, S100-immunoreactivity doesn't always mean the neuronal natures [10]. In addition, the specificity of NSE is also questionable [19].…”