title: Pseudoneoplasms in ectothermic animals.
abstract: Gross and cytologic similarities between certain non-neoplastic conditions and neoplasms in lower animals including fish, amphibians, and reptiles have invited misinterpretations and contested interpretations. Major categories of pseudo-neoplasms, illustrated by specific examples from material accessioned into the Registry of Tumors in Lower Animals, include infections by foreign organisms which resemble host cells (algal protothecosis and amebic pseudotumors); unusual normal conditions [giant islets of endocrine pancreas (Brockmann bodies) in liver, atypical sites of hematopoietic tissue]; nonparasitic hyperplasia (goiter, ectopic thyroid, erythroblastic proliferation suggestive of pernicious anemia, adenofibrosis); parasite-induced hyperplasia (trematode-induced fibrosis, ciliate-induced monocytic leukocytosis, trematode-induced melanosis, glochidiosis); dysmorphogenesis (teratoid anomalies); virus-induced hypertrophy (lymphocystis); and reactive lesions (metaplasia, regeneration, inflammation).
mesh_terms: D000230:Adenocarcinoma / Q000662:veterinary; D000236:Adenoma / Q000662:veterinary; D002759:Adenoma, Bile Duct / Q000662:veterinary; D000562:Amebiasis / Q000662:veterinary; D000663:Amphibians; D000752:Anemia, Pernicious / Q000662:veterinary; D000818:Animals; D001650:Bile Duct Neoplasms / Q000473:pathology; D002813:Chondrosarcoma / Q000662:veterinary; D000013:Congenital Abnormalities / Q000662:veterinary; D003937:Diagnosis, Differential; D005350:Fibroma / Q000662:veterinary; D005393:Fish Diseases / Q000473:pathology*; D005399:Fishes; D005880:Gills / Q000473:pathology; D006099:Granuloma / Q000473:pathology; D006410:Hematopoiesis; D006965:Hyperplasia; D007239:Infections / Q000662:veterinary; D007249:Inflammation / Q000662:veterinary; D007515:Islets of Langerhans / Q000648:ultrastructure; D007951:Leukemia, Myeloid / Q000662:veterinary; D015470:Leukemia, Myeloid, Acute / Q000662:veterinary; D007964:Leukocytosis / Q000662:veterinary; D008113:Liver Neoplasms / Q000662:veterinary; D008202:Lymphangioma / Q000662:veterinary; D009369:Neoplasms / Q000473:pathology / Q000662:veterinary*; D009810:Odontoma / Q000662:veterinary; D010212:Papilloma / Q000662:veterinary; D010273:Parasitic Diseases, Animal; D012104:Reptiles; D013961:Thyroid Gland / Q000473:pathology; D013964:Thyroid Neoplasms / Q000662:veterinary