Idiopathic anomalous congenital band causing small intestinal obstruction in a 5-month-old dog.

A 5-month-old, intact male, yellow Labrador retriever was presented with a 24-hour history of anorexia and vomiting. Abdominal imaging revealed the presence of a mechanical obstruction in the jejunum and peritoneal effusion. Cytologic evaluation and culture of the effusion prior to surgery identified a suppurative exudate with bacteria consistent with septic peritonitis and suspected to be related to the intestinal lesion. An exploratory laparotomy was performed, and a segment of jejunum was circumferentially severely constricted by an off-white, fibrous band of tissue. Resection and anastomosis of the strangulated segment of jejunum and excision of the constricting band provided resolution of the clinical signs. The dog made a complete recovery. Histologic evaluation revealed the band to be composed of fibrovascular and smooth muscle tissue, consistent with an idiopathic anomalous congenital band. No other gastrointestinal lesions were observed, either grossly at surgery or histologically in the resected segment of intestine. To our knowledge, a similar structure has not been reported in the veterinary literature. Key clinical message: Developmental abnormalities should be included in the differential list for younger patients with signs suggestive of gastrointestinal obstruction.

Anneau congénital anormal idiopathique provoquant une occlusion de l'intestin grêle chez un chien de 5 mois. Un Labrador retriever intact mâle âgé de 5 mois a été présenté avec une histoire de 24 heures d'anorexie et de vomissements. L'imagerie abdominale a révélé la présence d'une obstruction mécanique du jéjunum et d'un épanchement péritonéal. L'évaluation cytologique et la culture de l'épanchement avant la chirurgie ont identifié un exsudat suppuré avec des bactéries compatibles avec une péritonite septique et suspectées d'être liées à la lésion intestinale. Une laparotomie exploratoire a été réalisée et un segment de jéjunum était sévèrement resserré sur toute sa circonférence par une bande de tissu fibreux de couleur blanc-cassé. La résection et l'anastomose du segment étranglé du jéjunum et l'excision de la bande constrictive ont permis la résolution des signes cliniques. Le chien s'est complètement rétabli. L'évaluation histologique a révélé que la bande était composée de tissu musculaire fibrovasculaire et lisse, compatible avec une bande congénitale anormale idiopathique. Aucune autre lésion gastro-intestinale n'a été observée, ni grossièrement à la chirurgie ni histologiquement dans le segment réséqué de l'intestin. A notre connaissance, une structure similaire n'a pas été rapportée dans la littérature vétérinaire.Message clinique clé :Les anomalies du développement doivent être incluses dans la liste différentielle des patients plus jeunes présentant des signes évoquant une occlusion gastro-intestinale.(Traduit par Dr Serge Messier).

Malignant transformation of DMBA/TPA-induced papillomas and nevi in the skin of mice selectively lacking retinoid-X-receptor alpha in epidermal keratinocytes.

Retinoid-X-receptor alpha (RXRalpha), a member of the nuclear receptor (NR) superfamily, is a ligand-dependent transcriptional regulatory factor. It plays a crucial role in NR signalling through heterodimerization with some 15 NRs. We investigated the role of RXRalpha and its partners on mouse skin tumor formation and malignant progression upon topical DMBA/TPA treatment. In mutants selectively ablated for RXRalpha in keratinocytes, epidermal tumors increased in size and number, and frequently progressed to carcinomas. As keratinocyte-selective peroxisome proliferator-activated receptor gamma (PPARgamma) ablation had similar effects, RXRalpha/PPARgamma heterodimers most probably mediate epidermal tumor suppression. Keratinocyte-selective RXRalpha-null and vitamin-D-receptor null mice also exhibited more numerous dermal melanocytic growths (nevi) than control mice, but only nevi from RXRalpha mutant mice progressed to invasive human-melanoma-like tumors. Distinct RXRalpha-mediated molecular events appear therefore to be involved, in keratinocytes, in cell-autonomous suppression of epidermal tumorigenesis and malignant progression, and in non-cell-autonomous suppression of nevi formation and progression. Our study emphasizes the crucial role of keratinocytes in chemically induced epidermal and melanocytic tumorigenesis, and raises the possibility that they could play a similar role in UV-induced tumorigenesis, notably in nevi formation and progression to melanoma.

In utero exposure of mice to dibenzo[a,l]pyrene produces lymphoma in the offspring: role of the aryl hydrocarbon receptor.

Lymphoma and leukemia are the most common cancers in children and young adults; in utero carcinogen exposure may contribute to the etiology of these cancers. A polycyclic aromatic hydrocarbon (PAH), dibenzo[a,l]pyrene (DBP), was given to pregnant mice (15 mg/kg body weight, gavage) on gestation day 17. Significant mortalities in offspring, beginning at 12 weeks of age, were observed due to an aggressive T-cell lymphoblastic lymphoma. Lymphocytes invaded numerous tissues. All mice surviving 10 months, exposed in utero to DBP, exhibited lung tumors; some mice also had liver tumors. To assess the role of the aryl hydrocarbon receptor (AHR) in DBP transplacental cancer, B6129SF1/J (AHR(b-1/d), responsive) mice were crossed with strain 129S1/SvIm (AHR(d/d), nonresponsive) to determine the effect of maternal and fetal AHR status on carcinogenesis. Offspring born to nonresponsive mothers had greater susceptibility to lymphoma, irrespective of offspring phenotype. However, when the mother was responsive, an AHR-responsive phenotype in offspring increased mortality by 2-fold. In DBP-induced lymphomas, no evidence was found for TP53, beta-catenin, or Ki-ras mutations but lung adenomas of mice surviving to 10 months of age had mutations in Ki-ras codons 12 and 13. Lung adenomas exhibited a 50% decrease and a 35-fold increase in expression of Rb and p19/ARF mRNA, respectively. This is the first demonstration that transplacental exposure to an environmental PAH can induce a highly aggressive lymphoma in mice and raises the possibility that PAH exposures to pregnant women could contribute to similar cancers in children and young adults.