Immunohistochemical Characterization and Evaluation of Prognostic Factors in Canine Oral Melanomas with Osteocartilaginous Differentiation

Abstract

Melanomas are the most common malignant oral neoplasm in dogs. Osteocartilaginous differentiation in oral melanomas is a rare feature described both in veterinary and human medicine. Here, 10 cases of this type of neoplasm were used to study their immunohistochemical, biological, and clinical characteristics. Reactivity for S100 and melan A antigen was evaluated, and 4 prognosis factors (mitotic index, invasiveness of epithelium, nuclear atypia, and proliferation index) were analyzed and correlated with the clinical course of the neoplasms after diagnosis. Immunohistochemical analysis of the studied neoplasms, including the osteocartilaginous areas, showed positive immunoreaction for S100 and melan A, except in one dog, which was negative for melan A. Analysis of the results showed that oral melamonas with osteocartilaginous differentiation have a clinical course similar to that of other melanomas in the oral cavity. Analysis of the mitotic index and the expression of proliferation marker Ki-67 could be useful tools for predicting the biological behavior of these neoplasms.

Reduced Expression of E-cadherin and β-catenin and High Expression of Basal Cytokeratins in Feline Mammary Carcinomas With Regional Metastasis

“…All tissues were stained by the avidin-biotin-peroxidase complex method (ABC) as previously described 32 with several primary antibodies, whose clone, source, and pretreatment for antigen retrieval are summarized in Table 1. Counterstaining involved Mayer's hematoxylin.…”

Gingival Osteogenic Melanoma in Two Dogs

“…1,4,7,8,12,14,15,18,21 Only 15 cases of malignant melanoma with osteoid formation have been reported in the dog. 3,13,16,19 Because osteosarcoma and malignant melanomas have different prognoses and require different treatments, the recognition of the potential for malignant melanocytes to produce osteoid is important, especially if few melanin-containing neoplastic cells are present and the osteosarcoma-like phenotype is predominant. Two cases of oral osteogenic melanoma in dogs are reported with histologic and immunohistochemical characterization of this unusual tumor.…”

“…Currently, expectations, prognoses, and therapeutic plans for these masses are the same as for other malignant melanomas. 12,19 In human malignant melanoma, expression of bone sialoprotein (BSP) has been correlated with local and regional tumor spread. 18 In vitro studies have found that direct bone formation by melanoma cells is mediated by expression of BSP and the transcription factor Cbfa1/Runx2, which are normally only expressed in cells of mesenchymal origin.…”

Osteogenic Intraocular Melanoma in an Alpaca (Vicugna Pacos)

“…A mitotic rate of .3 mitoses per high-powered field has been used to predict early recurrence and possible metastasis of oral melanomas. 8 Immunostains used to confirm melanomas in cats, dogs, and humans include vimentin, S100, and melan A. 9 In the present alpaca, vimentin and melan A were positive, but S100 was negative.…”

“…4 In the current case, a melanoma with a high mitotic index and bone formation was diagnosed. Bone formation within a melanoma is a very rare occurrence, 8 although cases have been reported in humans 5 and in dermal 6 and oral 2 melanomas in dogs, but has not been From Gribbles Veterinary, Palmerston North, New Zealand (Hill), and Taranaki Veterinary Services, Stratford, New Zealand (Hughes). 1 Corresponding Author: Fraser I. Hill, Gribbles Veterinary, 840 Tremaine Avenue, PO Box 536, Palmerston North, New Zealand.…”