Editor's Choice - Radiation Dose Reduction During Contralateral Limb Cannulation Using Fiber Optic RealShape Technology in Endovascular Aneurysm Repair

OBJECTIVE

The increasing number of endovascular procedures has resulted in an increasing radiation burden, particularly for the treatment team. Fiber Optic RealShape (FORS) technology uses laser light instead of fluoroscopy to visualise the endovascular guidewire and catheters. These devices can be used during the navigational part of procedures, such as cannulation of the contralateral limb (CL) in endovascular aneurysm repair (EVAR). The aim of this study was to describe the effect of using FORS on radiation dose during CL cannulation in standard EVAR.

METHODS

This was a non-randomised, retrospective comparison study of prospectively collected, single centre data from FORS guided EVAR compared with a conventional fluoroscopy only guided EVAR cohort. A total of 27 FORS guided cases were matched 1:1 based on sex, age, and body mass index (BMI) with 27 regular (fluoroscopy only) EVARs. This study primarily focused on (1) technical success of FORS and (2) navigation time and radiation dose (cumulative air kerma [CAK], air kerma area product [KAP], and fluoroscopy time [FT]) during cannulation of the CL. In addition, overall procedure time and radiation dose of the complete EVAR procedure were studied.

RESULTS

In 22 (81%) of the 27 FORS guided cases the CL was successfully cannulated using FORS. All radiation dose parameters were significantly lower in the FORS group (CAK, p < .001; KAP, p = .009; and FT, p < .001) for an equal navigation time (p = .95). No significant differences were found when comparing outcomes of the complete procedure.

CONCLUSION

Use of FORS technology significantly reduces radiation doses during cannulation of the CL in standard EVAR.

Reduction of Radiation Exposure during Endovascular Treatment of Peripheral Arterial Disease Combining Fiber Optic RealShape Technology and Intravascular Ultrasound

Vascular surgeons and interventional radiologists face chronic exposure to low-dose radiation during endovascular procedures, which may impact their health in the long term due to their stochastic effects. The presented case shows the feasibility and efficacy of combining Fiber Optic RealShape (FORS) technology and intravascular ultrasound (IVUS) to reduce operator exposure during the endovascular treatment of obstructive peripheral arterial disease (PAD). FORS technology enables real-time, three-dimensional visualization of the full shape of guidewires and catheters, embedded with optical fibers that use laser light instead of fluoroscopy. Hereby, radiation exposure is reduced, and spatial perception is improved while navigating during endovascular procedures. IVUS has the capacity to optimally define vessel dimensions. Combining FORS and IVUS in a patient with iliac in-stent restenosis, as shown in this case report, enables passage of the stenosis and pre- and post-percutaneous transluminal angioplasty (PTA) plaque assessment (diameter improvement and morphology), with a minimum dose of radiation and zero contrast agent. The aim of this article is to describe the method of combining FORS and IVUS stepwise, to show the potential of merging both techniques in view of reducing radiation exposure and improving navigation tasks and treatment success during the endovascular procedure for the treatment of PAD.

Carotid tortuosity is associated with extracranial carotid artery aneurysms

BACKGROUND

Tortuous arteries may be associated with carotid dissection. The intima disruption caused by a carotid dissection is a possible cause of extracranial carotid artery aneurysms (ECAAs). The aim was to investigate if carotid tortuosity is also associated with ECAA in patients without presence or history of a carotid artery dissection.

METHODS

A retrospective case-control study was performed including 35 unilateral ECAA patients (cases) and 105 age- and sex-matched controls. Tortuosity was expressed as tortuosity-index (TI), curvature, and torsion measured on computed tomography angiography (CTA) data in 3Mensio Vascular and MATLAB by two independent investigators. Primary comparison was tortuosity in ipsi- versus contralateral carotid artery within the cohort of ECAA patients. Secondary comparison was tortuosity with ipsilateral carotid arteries in control patients. All observations were assessed on inter- and intra-operator reproducibility.

RESULTS

Carotid tortuosity was comparable within the cohort of ECAA patients (Spearman correlation 0.76, P<0.001), yet distinctively higher in comparison with unilateral controls. After adjustment for patient characteristics, presence of ECAA was associated with TI (β 0.146, 95% CI: 0.100-0.192). All tortuosity observations showed excellent inter- and intra-operator reproducibility.

CONCLUSIONS

Carotid tortuosity seems to be a risk factor for development of ECAA. Surveillance of individuals with increased carotid tortuosity therefore potentially ensures prompt diagnosis and treatment of ECAA. However, future research should investigate if persons with an increased tortuosity do indeed develop ECAA.

New tools to reduce radiation exposure during aortic endovascular procedures

INTRODUCTION

The evolution of endovascular surgery over the past 30 years has made it possible to treat increasingly complex vascular pathologies with an endovascular method. Although this generally speeds up the patient's recovery, the risks of health problems caused by long-term exposure to radioactive radiation increase. This warrants the demand for radiation-reducing tools to reduce radiation exposure during these procedures.

AREAS COVERED

For this systematic review Pubmed, Embase and Cochrane library databases were searched on 28 December 2021 to provide an overview of tools that are currently used or have the potential to contribute to reducing radiation exposure during endovascular aortic procedures. In addition, an overview is presented of radiation characteristics of clinical studies comparing a (potential) radiation-reducing device with conventional fluoroscopy use.

EXPERT OPINION

Radiation-reducing instruments such as fiber optic shape sensing or electromagnetic tracking devices offer the possibility to further reduce or even eliminate the use of radiation during endovascular procedures. In an era of increasing endovascular interventional complexity and awareness of the health risks of long-term radiation exposure, the use of these technologies could have a major impact on an ongoing challenge to move toward radiation-free endovascular surgery.

Clinical diagnostic clues in Crohn's disease: a 41-year experience

Determining the diagnosis of Crohn's disease has been highly difficult mainly during the first years of this study carried out at the Pontificia Universidad Catolica (PUC) Clinical Hospital. For instance, it has been frequently confused with Irritable bowel syndrome and sometimes misdiagnosed as ulcerative colitis, infectious colitis or enterocolitis, intestinal lymphoma, or coeliac disease. Consequently, it seems advisable to characterize what the most relevant clinical features are, in order to establish a clear concept of Crohn's disease. This difficulty may still be a problem at other medical centers in developing countries. Thus, sharing this information may contribute to a better understanding of this disease. Based on the clinical experience gained between 1963 and 2004 and reported herein, the main clinical characteristics of the disease are long-lasting day and night abdominal pain, which becomes more intense after eating and diarrhoea, sometimes associated to a mass in the abdomen, anal lesions, and other additional digestive and nondigestive clinical features. Nevertheless, the main aim of this work has been the following: is it possible to make, in an early stage, the diagnosis of Crohn's disease with a high degree of certainty exclusively with clinical data?

Heavy rainfall and waterborne disease outbreaks: the Walkerton example

Recent research indicates that excessive rainfall has been a significant contributor to historical waterborne disease outbreaks. The Meteorological Service of Canada, Environment Canada, provided an analysis and testimony to the Walkerton Inquiry on the excessive rainfall events, including an assessment of the historical significance and expected return periods of the rainfall amounts. While the onset of the majority of the Walkerton, Ontario, Escherichia coli O157:H7 and Campylobacter outbreak occurred several days after a heavy rainfall on May 12, the accumulated 5-d rainfall amounts from 8-12 May were particularly significant. These 5-d accumulations could, on average, only be expected once every 60 yr or more in Walkerton and once every 100 yr or so in the heaviest rainfall area to the south of Walkerton. The significant link between excess rainfall and waterborne disease outbreaks, in conjunction with other multiple risk factors, indicates that meteorological and climatological conditions need to be considered by water managers, public health officials, and private citizens as a significant risk factor for water contamination. A system to identify and project the impacts of such challenging or extreme weather conditions on water supply systems could be developed using a combination of weather/climate monitoring information and weather prediction or quantitative precipitation forecast information. The use of weather monitoring and forecast information or a "wellhead alert system" could alert water system and water supply managers on the potential response of their systems to challenging weather conditions and additional requirements to protect health. Similar approaches have recently been used by beach managers in parts of the United States to predict day-to-day water quality for beach advisories.

Abnormal fatty acid pattern in rheumatoid arthritis. A rationale for treatment with marine and botanical lipids

OBJECTIVE

To assess the fatty acid pattern in plasma and synovial fluid (SF) in rheumatoid arthritis (RA) and to determine clinical factors related to possible abnormalities.

METHODS

Thirty-nine patients with RA were included. SF samples were obtained from 9 patients. Disease activity was assessed using the Ritchie Articular Index and erythrocyte sedimentation rate. Fatty acids were assayed with gas liquid chromatography.

RESULT

Decreased levels of eicosapentaenoic acid (p < 0.0001) and total n3 polyunsaturated fatty acids (p < 0.05) were observed in plasma and in joint fluid, respectively. An increase of the substrates of delta-5-desaturase (C20:3n6 and C20:2n6) and decrease of their products (C20:4n6 and C22:4n6) was observed in plasma total lipids and phospholipids. The long chain mono-unsaturated fatty acids (C20: 1n9, C22: 1n9, C24: ln9) were increased in the joint fluid and in plasma phospholipids. Patients with active disease showed a mild decrease of several saturated fatty acids, n3, and n6 polyunsaturated fatty acids. Minor abnormalities or no changes in fatty acid profile were found related to use of steroids, nonsteroidal antiinflammatory drugs, and gold salts, or malnutrition.

CONCLUSION

The fatty acid pattern found in RA (decreased levels of n3 polyunsaturated fatty acids) may explain the beneficial effect of fish oil. Changes in n6 polyunsaturated fatty acids suggest that delta-5 desaturation is decreased and this might facilitate the antiinflammatory effect of botanical lipids in RA.

[Transcranial cytokine gradient and intestinal permeability in acute severe brain injury]

BACKGROUND

Acute brain injury is associated with a bimodal hypermetabolic state probably caused by cytokine secretion and high hormone and catecholamine concentrations. In a first stage, the brain would produce these substances and afterwards, another production source, most probably the splanchnic territory, would perpetuate the hypermetabolic state.

AIM

To investigate the cytokine production source and to assess intestinal permeability in acute brain injury in the absence of cerebral ischemia and systemic oxygen deficit.

PATIENTS AND METHODS

Arterial systemic and cerebral venous bulbar interleukin 1 beta and interleukin 6 levels were measured during the first seven days of evolution in 15 patients with acute brain injury. Serum lactate, the oxygen/lactate ratio, gastric intramucosal pH and intestinal permeability using the lactulose/mannitol test were also assessed in the same period.

RESULTS

High arterial and venous interleukin 1 beta and interleukin 6 levels were detected. A positive gradient for interleukin 6 levels was detected throughout the study period with normal intramucosal pH, lactate and oxygen/lactate ratio. There was also an early impairment of intestinal permeability in these patients.

CONCLUSIONS

High arterial and venous cytokine concentrations were detected in patients with acute brain injury. The positive gradient for interleukin 6 suggests a brain origin for this cytokine. Intestinal permeability is also altered in these patients.

[Enteral nutrition in severe ulcerative colitis. Digestive tolerance and nutritional efficiency]

BACKGROUNDS AND AIMS

Total parenteral nutrition (TPN) has been traditionally used as an adjunctive therapy in severe ulcerative colitis patients. We performed a prospective study to ascertain the safety, nutritional efficiency, tolerance and costs of total enteral nutrition in this situation.

METHODS

After 48 hours of intensive medical treatment, severe ulcerative colitis patients initiated enteral feeding with a polymeric formula. The formula concentration and volume were increased daily.

RESULTS

17 patients (7 women, 10 men; age 36.8 +/- 12.8 years) with a mean clinical activity score of 15.6 +/- 1.5 were included. In 14 patients (82.4%) enteral nutrition was well tolerated, attaining in 11 of them more than 80% of the caloric requirements by day 4. In 3 cases we observed vomiting and bloating. Prealbumin levels improved significantly from 11.1 +/- 3.4 mg/dl to 22.7 +/- 6.8 mg/dl (p = 0.002) at the end of enteral nutrition (11.8 +/- 4.7 days). Albumin and other nutritional parameters did not change.

CONCLUSIONS

Total enteral nutrition could be considered a safe and well tolerated nutritional support in these patients. Although albumin and other nutritional parameters did not change during the study period, the increase in prealbumin levels suggests a favourable anabolic effect of total enteral nutrition.

Plasma and mucosal fatty acid pattern in colectomized ulcerative colitis patients

Patients with inflammatory bowel disease (IBD) have increased plasma n3 polyunsaturated fatty acids (PUFAs), which in ulcerative colitis (UC) patients persists six months after colectomy, suggesting a primary abnormality in fatty acid (FA) metabolism in IBD. This finding needed to be confirmed in a larger series of UC long-term colectomized patients. We aimed to assess the plasma FA pattern in UC colectomized patients with either Brooke's ileostomy (UC-BI) or ileal pouch anal anastomosis (UC-IPAA) and the mucosal FA pattern in the ileal reservoir of the UC-IPAA patients. Plasma FAs were assessed in 63 UC colectomized patients (31 with BI and 32 with IPAA) and 30 controls. In 26 UC-IPAA (8 with pouchitis and 18 without pouchitis) and in 13 healthy controls gut mucosal FAs were also investigated. FAs were detected by capillary column gas-liquid chromatography. Increased levels of saturated fatty acids (SFAs) and decreased percentages of monounsaturated fatty acids (MUFAs) were observed in both groups of patients. There were no changes in plasma n3 and n6 PUFAs. The mucosal FA pattern of the ileal reservoir consisted of increased long-chain PUFAs, specially n6 PUFA, and a decrease of their essential precursors. High percentages of SFAs and low percentages of MUFAs were also seen. The plasma FA profile previously described in IBD is not observed long-term after colectomy in UC, suggesting that it is related with the presence of inflamed intestine. High concentrations of SFAs and decreased percentages of MUFAs might represent early events in disturbed FA metabolism in IBD. The changes in FAs of the ileal reservoir, which closely resemble those found in human and experimental IBD, probably represent a common pattern of intestinal inflammation.

Factors related to the presence of IgA class antineutrophil cytoplasmic antibodies in ulcerative colitis

OBJECTIVES

Few studies have assessed the IgA antineutrophil cytoplasmic antibody (ANCA) positivity in ulcerative colitis patients and there is no information about factors related to its synthesis and its status after colectomy. The aims of the study were to assess the serum IgA ANCA prevalence in ulcerative colitis patients, both nonoperated and operated, and to determine the clinical factors related to this positivity.

METHODS

Fifty-four ulcerative colitis patients, 63 ulcerative colitis colectomized patients (32 with Brooke's ileostomy and 31 with ileal pouch anal anastomosis), and 24 controls were studied. Antineutrophil cytoplasmic antibodies were detected by specific indirect immunofluorescent assays.

RESULTS

The percentage of IgA ANCA was significantly higher in patients with ileal pouch anal anastomosis (45%) than in patients with Brooke's ileostomy (22%). There were no differences related to the presence of pouchitis in ileal pouch anal anastomosis patients. Patients with nonoperated extensive colitis (47%) had a significantly higher percentage of IgA ANCA than patients with proctitis (19%). Total percentage of ANCA (IgA and/or IgG) tended to be higher in ulcerative colitis and in patients with ileal pouch anal anastomosis than in patients with Brooke's ileostomy. However, in ileal pouch anal anastomosis patients, ANCA positivity was mainly due to exclusive IgA production.

CONCLUSIONS

A substantial percentage of ulcerative colitis patients, and especially colectomized patients with ileal pouch anal anastomosis, had IgA ANCA, suggesting that ANCA production in ulcerative colitis might be stimulated by an immune reaction in the intestinal mucosa.

[Growth hormone deficiency in patients with chronic heart failure]

BACKGROUND

Experimental and preliminary clinical data in patients with dilated cardiomyopathy show that growth hormone has a positive inotropic effect and contributes to peripheral vasodilatation. However, there is little information about the activity of growth hormone-IGF-1 axis in patients with chronic heart failure.

AIM

To measure growth hormone and IGF-1 levels in patients with chronic heart failure.

PATIENTS AND METHODS

Nine patients, aged 49 to 76 years old, 7 male, were studied. Seven had an idiopathic dilated cardiomyopathy and 2 a coronary heart disease. All had a stable cardiac failure, in functional capacity II or III and were receiving digoxin, furosemide and potassium supplements. Thyroid hormone levels, basal and exercise growth hormone and IGF-1 levels were measured and compared with reference values for American populations. Left ventricular ejection fraction was measured with an isotopic technique and nutritional status using anthropometry and indirect calorimetry.

RESULTS

Anthropometric measures, basal and post-prandial oxygen consumption were within normal limits. Thyroid hormone levels were normal. During maximal exercise, growth hormone levels were 2.56 +/- 4.1 ng/ml and IGF-1 levels were 0.56 +/- 0.61 mU/ml. These values were significantly lower than expected for age and sex.

CONCLUSIONS

These patients with chronic cardiac failure have lower than normal growth hormone and IGF-1 levels.

Antineutrophil cytoplasmic antibodies in sera from colectomised ulcerative colitis patients and its relation to the presence of pouchitis

BACKGROUND

Few studies have evaluated the influence of colectomy on antineutrophil cytoplasmic antibody (ANCA) positivity in ulcerative colitis (UC). In small series of patients it has been suggested that ANCA positivity in UC might be predictive for development of pouchitis after colectomy.

AIMS

To assess the prevalence of ANCA in UC patients treated by colectomy and a Brooke's ileostomy (UC-BI) or ileal pouch anal anastomosis (UC-IPAA), and the relation between the presence of ANCA, the type of surgery, and the presence of pouchitis.

SUBJECTS

63 UC patients treated by colectomy (32 with UC-BI and 31 with UC-IPAA), 54 UC, and 24 controls.

METHODS

Samples were obtained at least two years after colectomy. ANCA were detected by indirect immunofluorescent assay.

RESULTS

There were no differences between patients with (36.3%) or without pouchitis (35.0%) and between patients with UC (55%), UC-BI (40.6%), and UC-IPAA (35.4%). However, ANCA prevalence significantly decreases in the whole group of operated patients (38.0%) compared with non-operated UC (p = 0.044).

CONCLUSIONS

The prevalence of ANCA in operated patients was significantly lower than in non-operated UC, suggesting that it might be related either to the presence of inflamed or diseased tissue. ANCA persistence is not related to the surgical procedure and it should not be used as a marker for predicting the development of pouchitis.

Impact of portacaval anastomosis on plasma fatty acid profile in cirrhosis: a randomized 24-month follow-up study

BACKGROUND

Portacaval anastomosis has an hypolipemic effect in familial hypercholesterolemia and in healthy animals. In cirrhosis, it raises serum cholesterol, but there is no information on its effect upon plasma fatty acids. However, indirect data suggest that portacaval shunting might contribute to the polyunsaturated fatty acid deficit of these patients. We assessed the effect of portacaval anastomosis on plasma fatty acid profile in cirrhosis.

METHODS

Forty-four Child-Pugh class A/B bleeding cirrhotics were randomized to be treated with portacaval anastomosis (n = 20) or nonsurgical therapy (n = 24). Fatty acid profile in plasma total lipids, alcohol intake, anthropometry, Child-Pugh score, serum cholesterol, triglycerides, and antioxidant micronutrients were assessed before and 3, 6, 12, 18, and 24 months after surgery or the start of nonsurgical therapy. Time course of plasma fatty acids was assessed using unbalanced repeated measures models with the above mentioned variables acting as covariates.

RESULTS

No changes in the time course of percent plasma saturated, monounsaturated, and essential fatty acids were found between groups. Percent long-chain omega-6 and omega-3 polyunsaturated fatty acids decreased during follow-up in shunted patients compared with controls (p = .007 and p < .0005). However, this was not due to a true decrease in polyunsaturated fatty acid levels but to greater increases in saturated and monounsaturated fatty acid concentrations in shunted patients compared with control patients (p = .047 and p = .006).

CONCLUSIONS

Portacaval anastomosis does not worsen plasma polyunsaturated fatty acid deficiency in cirrhosis. However, by increasing saturated and monounsaturated fatty acids, it further decreases plasma lipid unsaturation.

Changes of the mucosal n3 and n6 fatty acid status occur early in the colorectal adenoma-carcinoma sequence

Despite data favouring a role of dietary fat in colonic carcinogenesis, no study has focused on tissue n3 and n6 fatty acid (FA) status in human colon adenoma-carcinoma sequence. Thus, FA profile was measured in plasma phospholipids of patients with colorectal cancer (n = 22), sporadic adenoma (n = 27), and normal colon (n = 12) (control group). Additionally, mucosal FAs were assessed in both diseased and normal mucosa of cancer (n = 15) and adenoma (n = 21) patients, and from normal mucosa of controls (n = 8). There were no differences in FA profile of both plasma phospholipids and normal mucosa, between adenoma and control patients. There were considerable differences, however, in FAs between diseased and paired normal mucosa of adenoma patients, with increases of linoleic (p = 0.02), dihomogammalinolenic (p = 0.014), and eicosapentaenoic (p = 0.012) acids, and decreases of alpha linolenic (p = 0.001) and arachidonic (p = 0.02) acids in diseased mucosa. A stepwise reduction of eicosapentaenoic acid concentrations in diseased mucosa from benign adenoma to the most advanced colon cancer was seen (p = 0.009). Cancer patients showed lower alpha linolenate (p = 0.002) and higher dihomogammalinolenate (p = 0.003) in diseased than in paired normal mucosa. In conclusion changes in tissue n3 and n6 FA status might participate in the early phases of the human colorectal carcinogenesis.

[Variability of measured energy expenditure in patients with acute pancreatitis: is it possible to obtain a reliable pathology factor for these cases?]

Energy expenditure was measured in 55 patients with acute pancreatitis, during variable periods ranging from 1 to 5 weeks and it was compared with estimated energy expenditure according to Harris Benedict equations. Patients with severe pancreatitis had similar measured and measured/estimated energy expenditure rations, compared to those with mild pancreatitis (1678 +/- 349.6 kcal/day and 1.1 +/- 0.19 vs 1632 +/- 383 kcal/day and 1.06 +/- 0.19). There was a high dispersion of measured/estimated rations (0.67 - 1.7) that precluded the calculation of a reliable energy expenditure correction factor for this disease. It is concluded that energy expenditure must be measured and not estimated, when planning an adequate nutritional support in patients with acute pancreatitis.

[Non-insulin-dependent diabetics with secondary failure: insulin therapy at bedtime combined with glibenclamide]

Secondary failure and the requirement is common in patients with non-insulin dependent diabetes mellitus. The combination of sulfonylureas with NPH insulin at bedtime has been proposed to avoid high doses of insulin. We treated 18 patients (2 men, age range 47-76 yr) non respondent to diet and glibenclamide, combining NPH insulin in an average dose of 0.3 +/- 0.03 U/kg BW at bedtime for 6 months. Fasting serum glucose improved from 256 +/- 11 to 132 +/- 6 mg/dl and HbA1C from 13.6 +/- 0.4 to 9.9 +/- 0.2%. Four patients achieved a good control (defined as a HbA1C < 9), 9 a fair control (HbA1C 9.1-10) and 5 persisted with a bad control (HbA1C > 10). Well controlled patients were younger, had a shorter duration of diabetes and had a non significantly higher body mass index. Fasting serum insulin and C peptide levels achieved after glucagon injection were not predictors of the metabolic response to combined therapy. Tolerance to treatment was good, without changes in blood pressure or serum lipids and with a low incidence of hypoglycemia. There was a mean increase of 3.6 kg in body weight. After 6 months of therapy, maximum achieved C peptide values after glucagon increased from 3.3 +/- 0.3 to 4.5 +/- 0.4 ng/ml. It is concluded that combined glibenclamide and NPH insulin at bedtime is useful to treat secondary failure in non-insulin dependent diabetic patients, but their response in variable and non dependent on their beta insular secretion.

[Serum lipids, HDL2 and HDL3 cholesterol and apolipoproteins A1 and B as predictors of coronary artery disease diagnosed by coronarography]

Serum levels of total, HDL2 and HDL3 cholesterol, triglycerides and apolipoproteins A1 and B were compared in 100 Chilean males with (n = 80) or without (n = 20) coronary artery disease (CAD). The presence and severity of CAD was determined by an angiographic score. Discriminating power, sensitivity, specificity and positive predictive value for CAD were calculated for all variables. As an isolated factor, total cholesterol had the greatest discriminating power (p less than 0.002): 21% of patients with CAD had cholesterol levels below 200 mg/dl while no patient with cholesterol over 275 mg/dl was free of disease. Even though all cases with HDL cholesterol below 25 mg/dl belonged in the CAD group, this factor had no overall discriminating power. Total cholesterol/HDL cholesterol ratio had the greatest discriminating power (p less than 0.001) while total/HDL2 cholesterol had the best positive predictive value.

Malignant mesothelioma of the tunica vaginalis in a dog

A 12-year-old Scottish terrier had a scrotal mass which was diagnosed as a malignant mesothelioma of the tunica vaginalis. The tumour resulted in a rapidly fatal clinical course with direct extension into the peritoneal cavity via the inguinal canal; there were no haematogenous or lymphatic metastases. This is the first case report of such a tumour in the dog. The histology and differential diagnoses of these tumours and a review of similar tumours in other species and possible causative agents are given.