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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03627

    Spontaneous multiple cutaneous mixed tumors in Japanese giant salamander Andrias japonicus

    Sho Kadekaru, Hiroshi Shimoda, Kazushi Kuwabara, Yumi Une*

    *Corresponding author:

    ABSTRACT: We examined 7 cutaneous mixed tumors in 2 conserved wild Japanese giant salamanders Andrias japonicus. The tumors had enlarged, re-occurred, and/or increased. We sampled the tumors from these animals and 3 verrucose protrusions from 3 unaffected animals, as controls, and examined them pathologically and virologically. The tumors of size 5 mm to 4 cm were papillary protrusions or pendulated on the skin surface. The cut surface of the tumor was white, lobulated, partially hard, and contained mucus. All tumors presented similar histological characteristics with a hyaline structure and exhibited biphasic proliferation, with neoplastic epithelial cells partially composing the pseudo-ductal structure and staining positive for cytokeratin AE1/AE3. vimentin 3B4-positive blast-like mesenchymal cells proliferated to fill the gaps in the epithelial components. Transition from unique mucous gland to neoplastic tissue was observed. The hyaline structure was stained blue by AZAN stain, Alcian blue-PAS double stain, and toluidine blue stains (TB stain) of pH 7.0, but was unstained by TB stain of pH 4.1 and 2.5. The mucus in the neoplastic tissue and in the mucous gland in verrucose protrusion was stained blue by Alcian blue-PAS double stain; TB staining at pH 7.0, 4.1, and 2.5 revealed metachromasy. No virus was detected in the tumors. The 7 tumors were diagnosed as cutaneous mixed tumors, and it was confirmed that the neoplastic cells originated from the mucous gland in the dermis. The biological behavior and pathological development of tumors should be elucidated because the tumors have the potential to negatively affect A. japonicus.