Abstract
Skin lesions associated with Mycobacteria spp. in cats can take a variety of forms. The authors of this study analyzed 29 cases of feline cutaneous mycobacteriosis in order to correlate histologic appearance with specific mycobacterial organisms. Archival tissue sections were stained with H&E and modified Fite's stain, and speciation of organisms was performed by polymerase chain reaction for Actinomycetales 16S ribosomal RNA. On histopathologic examination, there were 23 cases of feline leprosy, three cases of atypical mycobacteriosis and three cases classified as miscellaneous. Sequence analysis of PCR products revealed the presence of ten different Actinomycetales organisms, nine of which belong to the genus Mycobacterium. Current classification schemes of feline cutaneous mycobacteriosis which attempt to correlate histologic lesions with specific microorganisms were reviewed. The authors concluded that feline cutaneous mycobacteriosis represents a syndrome rather than a single entity, with multiple etiologic agents, and that use of molecular techniques to identify those agents should be employed.
Davies JL, Sibley JA, Myers S, Clark EG, Appleyard GD. Histological and genotypical characterization of feline cutaneous mycobacteriosis: A retrospective study of formalin-fixed paraffin-embedded tissues. Vet Dermatol
Eosinophilic enteritis is an uncommon lesion that has been reported in multiple species. In horses it may be one manifestation of multisystemic eosinophilic epitheliotrophic syndrome. In this report the authors describe twelve cases of idiopathic focal eosinophilic enteritis diagnosed at one veterinary institution in the United Kingdom since 2000. All horses presented with signs of small intestinal obstruction. Gross lesions at the time of laparotomy included erythematous circumferential constrictions and/or circumscribed plaques on the serosal surface at the site of obstruction. Histologically these sites had an intense transmural infiltrate of eosinophils, along with edema, smooth muscle necrosis, activated fibroblasts and proliferation of capillaries. The majority of horses were discharged from the hospital following jejunal resection. A specific management practice that could contribute to the formation of these lesions was not be identified, and parasites were not present in any of the cases. The authors speculate that idiopathic focal eosinophilic enteritis could represent an emerging disease in the equine population.
Archer DC, Edwards GB, Kelly DF, French NP, Proudman CJ. Obstruction of equine small intestine associated with focal idiopathic eosinophilic enteritis: An emerging disease?. Vet J
Investigators in the laboratory of Judah Folkman have developed a mouse model system in which they can study the molecular and morphologic changes associated with progression from a dormant tumor to one that is rapidly expansive. The behavioral phenotype appears to coincide with an angiogenic switch. Angiogenic and nonangiogenic clones of a human liposarcoma cell line were implanted subcutaneously and orthotopically into SCID mice. Both clones contained fully transformed cells with equal proliferative potential. Tumor burden was assessed over time using non-invasive bioluminescence imaging. Angiogenic clones grew rapidly and had increased microvessel density. Nonangiogenic clones remained dormant for 87–120 days after tumor inoculation, after which time they exited dormancy and exhibited rapid, expansile growth and increased microvessel density. The dormant cells had high levels of the angiogenic inhibitors thrombospondin-1 and tissue inhibitor of metalloproteinase-1, which the authors speculate contribute to the dormant status. What precipitates the proposed angiogenic switch is not known. This model may prove useful for understanding the biology of occult tumors, cancer in situ and micrometastases.
Almog N, Henke V, Flores L. Prolonged dormancy of human liposarcoma is associated with impaired tumor angiogenesis. FASEB J
Feline acne of the chin is a common disorder in domestic cats. Although there are many factors suspected to be involved in the pathogenesis of this condition, few systematic studies have been performed. The authors evaluated 22 affected cats and 5 non-affected cats. Castrated males represented 73% of the affected cats. The most common histopathologic lesions were lymphoplasmacytic periductal inflammation, sebaceous gland dilatation, follicular hyperkeratosis and plugging, and pyogranulomatous inflammation. Since viral etiologies had been suggested by others, the authors performed immunohistochemistry for feline calicivirus and feline herpesvirus-1. Only one affected cat was positive for calicivirus. Cultures revealed multiple types of bacteria including Staph, Strep, E. coli, Bacillus and Micrococcus. In addition, Malassezia was present in 22% of the affected cats. The authors conclude that their data support previous hypotheses that feline acne is a disorder of follicular keratinization, exacerbated by secondary infection.
Jazic E, Coyner KS, Loeffler DG, Lewis TP. An evaluation of the clinical, cytological, infectious and histopathological features of feline acne. Vet Dermatol
Investigators have developed a new mouse model for human epidermolytic hyperkeratosis (EHK). In chemical mutagenesis studies they identified mice with marked blistering and erosions of the footpads, along with increased pigmentation and hyperkeratosis. Histopathologic analysis of the footpads demonstrated suprabasal keratinocyte lysis, acanthosis, thickened stratum corneum and increased epidermal pigmentation. A missense mutation was identified in the Keratin 1 gene in heterozygous mice that is predicted to disrupt interactions between acidic keratin and basic keratin during formation of keratin intermediate filaments. This exact mutation has been found in a human with EHK, supporting the notion that these mice are a good model for the human disease. Homozygous mutant mice displayed severe lesions and early postnatal death. The authors speculate that proliferation of basal keratinocytes results in paracrine stimulation of nearly pigmentary cells and subsequent hyperpigmentation. These mice, along with other pigmentation mutants developed by this group, may be valuable tools for studying a variety of hyperpigmentation disorders.
McGowan KA, Aradhya S, Fuchs H, de Angelis MH, Barsh GS. A mouse Keratin 1 mutation causes dark skin and epidermolytic hyperkeratosis. J Invest Dermatol