A 7-year-and-8-month-old, male degu (Octodon degus) with anorexia, depression, and labored breathing was found to have a thoracic effusion and enlargement of the right testis on radiographic examination. Despite treatment, the animal died. At necropsy, hepatomegaly, splenomegaly, and multifocal nodules on the intestinal serosa and mesentery were observed. Histologically, the foci were densely cellular invasive neoplasms composed of sheets of round to polygonal cells, with occasional multinucleated giant cells. Immunohistochemically, the neoplastic cells were immunopositive for ionized calcium-binding adapter molecule 1, human leukocyte antigen-DR, and CD204. These findings were consistent with disseminated histiocytic sarcoma.

Apolipoprotein E (ApoE) is involved in cholesterol transport among cells and also plays an important role in amyloid formation, co-depositing with amyloid fibrils in various types of amyloidosis. Although the in vivo amyloidogenicity of ApoE has not been previously demonstrated, this study provides evidence of ApoE amyloidogenicity in leopard geckos (Eublepharis macularius), belonging to the class Reptilia. Histologically, amyloid deposits were localized within cholesterol granulomas and exhibited positive Congo red staining, with yellow to green birefringence under polarized light. On mass spectrometry-based proteomic analysis, ApoE was detected as a dominant component of amyloid; of the full length of the 274 amino acid residues, peptides derived from Leu185-Arg230 were frequently detected with non-tryptic truncations. Immunohistochemistry with anti-leopard gecko ApoE antibody showed positive reactions of amyloid deposits. These results show that ApoE is an amyloid precursor protein within the cholesterol granulomas of leopard geckos. Although further investigations are needed, the C-terminal region of ApoE involved in amyloid formation is a lipid-binding region, and there should be a relationship between amyloidogenesis and the development of cholesterol granulomas in leopard geckos. This study provides novel insights into the pathogenesis of ApoE-related diseases.

関東圏にて飼育されていた17歳齢，去勢雄の木曽馬が活力低下，食欲廃絶，及び四肢強直や眼球振盪などの神経症状を呈し，起立不能となって死亡した．剖検時，両側腎臓，及び胃小弯部に灰白色結節が認められた．病理組織学的に，脳，両側腎臓，及び胃において，多巣性かつ無秩序に分布した肉芽腫性炎が認められた．いずれの病変内においても，ラブディティス型の食道を有する幅約20μmの線虫が多数混在していた．線虫の形態学的特徴，及び抽出された28SリボソームRNA遺伝子のシーケンスの結果，線虫はHalicephalobus gingivalisと考えられた．これまでに日本在来馬における本症の発生報告は見当たらないため，日本在来馬の保護のため，より注視する必要がある．

A nine-year-old, castrated male mixed-breed dog presented with a three-month history of sneezing and stertorous breathing. Computed tomography revealed a soft tissue mass in the left nasal cavity with lysis of the cribriform plate. The mass was diagnosed as intranasal sarcoma based on histopathological analysis. The tumor cells were immunohistochemically positive for KIT and platelet-derived growth factor receptor α/β and negative for vascular endothelial growth factor receptor 2 and cyclooxygenase-2. Treatment with toceranib phosphate (TOC) and firocoxib reduced the tumor size, which was defined as partial response (PR). After PR induction, TOC alone mediated survival for 205 days. This case report suggests that the combination of TOC and possibly firocoxib may be a therapeutic option for canine intranasal sarcoma.

An estimated 6-yr-old female leopard gecko (Eublepharis macularius) presented with a raised spherical mass on the head. Grossly, the skin overlying the mass was smooth, with a focal area of ulceration. Histologically, the dermis was expanded by a well-demarcated, poorly cellular single expansile cyst. The cyst was lined by stratified squamous epithelium and was filled with an accumulation of tightly packed lamellar keratin with regular folding, resembling keratinization of the epidermis. Neither cellular nor nuclear atypia was observed, and there were no mitotic figures in the lining epithelium. The histopathological findings were consistent with an epidermal cyst. To the best of the authors' knowledge, an epidermal cyst in the dermis of the head has not been documented previously in a captive leopard gecko.

A central bearded dragon (Pogona vitticeps) presented with periorbital swelling and exophthalmos. A retrobulbar mass was detected, and enucleation with the mass was performed. Histologically, the mass was composed of a dense sheet and interlacing bundles of round to polygonal to short spindle-shaped cells with occasional bizarre mononuclear and multinucleated giant cells. Immunohistochemically, the neoplastic cells had various degrees of membranous and/or cytoplasmic granular reactivity to anti-ionized calcium-binding adapter molecule 1 and anti-CD204 antibodies. Ultrastructurally, the neoplastic cells had irregular nuclei and abundant cytoplasm with membrane-bound electron-dense lysosomes and endoplasmic reticula. These findings were consistent with a histiocytic sarcoma. The present study provided a detailed description of retrobulbar histiocytic sarcoma for the first time in a central bearded dragon.

Two vascular tumors in two Argentine horned frogs (Ceratophrys ornata) are described. Case 1 involved a 7-yr-1-month-old Argentine horned frog that had a splenic mass with a sanguineous coelomic effusion. Histologically, the splenic parenchyma was effaced by a poorly demarcated, invasive mass consisting of spindle cells with marked nuclear atypia forming irregular blood vessel channels containing blood. Case 2 involved a pedunculated facial mass located at the upper right lip of an over-8-month-old Argentine horned frog. Histologically, the well-demarcated, poorly cellular mass consisted of sparse proliferation of spindle cells forming irregular slits with prominent edema. Immunohistochemically, the neoplastic cells of both cases were positive for anti-CD31 antibody. The diagnoses were hemangiosarcoma in Case 1 and lymphangioma in Case 2. To the best of the authors' knowledge, this is the first description of neoplastic diseases in captive Argentine horned frogs.