Pathology in Practice

In collaboration with the American College of Veterinary Pathologists

Medial Arterial Calcification: JACC State-of-the-Art Review

Medial arterial calcification (MAC) is a chronic systemic vascular disorder distinct from atherosclerosis that is frequently but not always associated with diabetes mellitus, chronic kidney disease, and aging. MAC is also a part of more complex phenotypes in numerous less common diseases. The hallmarks of MAC include disseminated and progressive precipitation of calcium phosphate within the medial layer, a prolonged and clinically silent course, and compromise of hemodynamics associated with chronic limb-threatening ischemia. MAC increases the risk of complications during vascular interventions and mitigates their outcomes. With the exception of rare monogenetic defects affecting adenosine triphosphate metabolism, MAC pathogenesis remains unknown, and causal therapy is not available. Implementation of genetics and omics-based approaches in research recognizing the critical importance of calcium phosphate thermodynamics holds promise to unravel MAC molecular pathogenesis and to provide guidance for therapy. The current state of knowledge concerning MAC is reviewed, and future perspectives are outlined.

Efficacy and safety of glucose, glucose and polidocanol combination, liquid polidocanol and polidocanol foam in the treatment of reticular veins: A randomized study in rabbits

OBJECTIVE

To compare the efficacy and safety of sclerosing agents injected in dorsal veins of rabbit ears.

METHODS

Sixty ears of 30 rabbits were randomly allocated in: 1% liquid polidocanol, 1% polidocanol foam, 0.2% polidocanol-glucose 70% solution, glucose 75% or 0.9% saline. Outcomes included efficacy (luminal occlusion), complications (phlebitis, neovascularization, ulceration at the puncture site, necrosis and local inflammation) and histology (sclerosis, recanalization vein and surrounding tissues inflammation, blood extravasation, recanalization, lymphangiogenesis, destruction of cartilage and neoangiogenesis).

RESULTS

Sclerosis was superior in Foam Group (76.9%), but also with 30.7% necrosis (p = 0.003), 46.15% ulceration (p = 0.003), and 69.2% local inflammation (p < 0.0001). Neovascularization were similar. Histology showed 38.5% phlebitis (p = 0.004) and necrosis (p = 0.03) in the foam group.

CONCLUSIONS

Sclerosis with foam and liquid polidocanol were superior to the other groups, but specially polidocanol foam at the expense of greater frequency of adverse events.

Early-stage endometrial cancer, CTNNB1 mutations, and the relation between lymphovascular space invasion and recurrence

INTRODUCTION

Women diagnosed with early-stage (FIGO 1) endometrial cancer, grade 1 and 2 can have a good prognosis. Most of these women can be treated successfully with a hysterectomy and bilateral salpingo-oophorectomy and without the additional adjuvant treatment that is accompanied by more risks for complications. However, when recurrence does occur, the consequences can be dire. Accurate decisions must therefore be made by surgeons to avoid either under- or over-treatment. Risk and patient stratification for tailoring treatment still need further improvement. Both histopathology and genetic variants could be integrated into the decision process if relevant factors were identified.

MATERIAL AND METHODS

Morphological features and the presence of selected genetic mutations in isolated malignant endometrial epithelial cells from these tumors were analyzed in a strictly defined cohort of FIGO 1, grade 1 and 2 low-risk endometrial cancer. Their presence in this cohort, their relation to recurrence, and the association between histopathological features and mutations were determined. This analysis was performed using archival formalin-fixed paraffin-embedded tissue, complete re-evaluation of histopathological features, laser capture microdissection of epithelial cells, and a polymerase chain reaction-based mutational screening assay.

RESULTS

Twenty-one women with recurrence, after initial identification as low-risk endometrial cancer, were compared with 20 matched control women. The histological marker of lymphovascular invasion was significantly associated with recurrence. There was also a very high prevalence of mutations in CTNNB1 gene, occurring in 50% of this cohort. PTEN mutations were also observed in 27.8% of cases and PIK3CA mutations in 22.2%; none of these mutations were significantly related to recurrence.

CONCLUSIONS

This study supports the importance of lymphovascular space invasion to identify women with significant risk for recurrence in initially low-risk, early-stage endometrial cancer. It also identifies CTNNB1 as a significant mutation in early-stage disease, and although it may not represent a marker for recurrence its high prevalence in early stage disease could have relevance for both pathogenesis and early treatment.

[Melanosis of the urinary bladder]

Melanosis of the bladder is rare. Only 10 cases have been described in the literature. We present the case of an 80-year-old woman with neurogenic lower urinary tract dysfunction due to spinal paralysis. During the diagnostic work-up which included cystoscopy, black spots in the bladder wall were observed. Histopathological evaluation revealed a benign suburothelial melanosis. Thus, with cystoscopic suspicion of a malignancy (melanoma), a biopsy is mandatory and regular cystoscopic follow-up is recommended.

Medial vascular calcification revisited: review and perspectives

Vascular calcifications (VCs) are actively regulated biological processes associated with crystallization of hydroxyapatite in the extracellular matrix and in cells of the media (VCm) or intima (VCi) of the arterial wall. Both patterns of VC often coincide and occur in patients with type II diabetes, chronic kidney disease, and other less frequent disorders; VCs are also typical in senile degeneration. In this article, we review the current state of knowledge about the pathology, molecular biology, and nosology of VCm, expand on potential mechanisms responsible for poor prognosis, and expose some of the directions for future research in this area.

[Psammomatous tenosynovialitis of hand and forearm - three new cases]

We report about three new observations of psammomatous tenosynovialitis on hand and forearm and performed a review of literature. To the best of our knowledge cases 7, 8 and 9 in the medical literature are now published.

Postoperative determination of the degree of carotid artery stenosis

This article describes the VascMorph 1a prototype software and reports first results obtained with postoperative determination of the degree of stenosis in the carotid artery.

[Recurrence of a tendon sheath tumor on the hand consisting of three morphological components]

We report of a benign, recurrent tendon sheath tumour. Histologically, three different morphological components were observed.

The pedunculopontine nucleus is related to visual hallucinations in Parkinson's disease: preliminary results of a voxel-based morphometry study

Visual hallucinations (VH) are common in Parkinson’s disease (PD) and lead to a poor quality of life. For a long time, dopaminergic therapy was considered to be the most important risk factor for the development of VH in PD. Recently, the cholinergic system, including the pedunculopontine nucleus (PPN), has been implicated in the pathophysiology of VH. The aim of the present study was to investigate grey matter density of the PPN region and one of its projection areas, the thalamus. Thirteen non-demented PD patients with VH were compared to 16 non-demented PD patients without VH, 13 demented PD patients (PDD) with VH and 11 patients with dementia with Lewy bodies (DLB). Isotropic 3-D T1-weighted MRI images (3T) were analysed using voxel-based morphometry (VBM) with the PPN region and thalamus as ROIs. PD and PDD patients with VH showed grey matter reductions of the PPN region and the thalamus compared to PD patients without VH. VH in PD(D) patients are associated with atrophy of the PPN region and its thalamic target area, suggesting that a cholinergic deficit may be involved in the development of VH in PD(D).

[Ascending aortic and pulmonary trunk aneurysms]

A case of two non-atherosclerotic aneurysms localised in the ascending aorta and in the pulmonary trunk is presented. Histopathologically, a severe granulomatous inflammation affecting the whole aneurysms wall was documented. To the best of our knowledge it is the second ever documented case of simultaneous occurrence of aneurysms in the aorta and the pulmonary artery.

Insufficient arteriovenous fistulae in hemodialysis patients

BACKGROUND

For an accurate assessment of structural changes in arteriovenous fistulae (AVF) a microscopic analysis is mandatory.

METHODS

25 insufficient AVF were analyzed with the light microscope using standard histological and immunohistochemical techniques.

RESULTS

In 7 patients (28%) atherosclerotic lesions as causes of AVF insufficiency were found. The other 18 patients (72%) had an inhomogeneous spectrum of nonatherosclerotic lesions, for instance intimal hyperplasia.

CONCLUSIONS

Histopathologic analysis of insufficient AVF helps clarify the underlying changes in the structure of the vessel wall.

[Anal metastasis from a lung cancer]

We report an anal metastasis from a lung cancer which was diagnosed on symptoms mimicking an acute anal abcess. The diagnosis was based on specific immunohistochemistry.

Non-invasive evaluation of atherosclerosis with contrast enhanced 16 slice spiral computed tomography: results of ex vivo investigations

OBJECTIVE

To evaluate the diagnostic accuracy of 16 slice computed tomography (CT) in determining plaque morphology and composition in an experimental setting. The results were compared with histopathological analysis as the reference standard.

METHODS

Nine human popliteal arteries derived from amputations because of atherosclerotic disease were investigated with multislice spiral CT (MSCT). Atherosclerotic lesions were morphologically classified (completely or partially occlusive, concentric, eccentric), and tissue densities were determined within these plaques. In addition, vessel dimensions were quantitatively measured.

RESULTS

The results were compared with histological analysis. The concordance index kappa for morphological classification was 0.88. Plaque density (n = 51 lesions) was significantly different (p < 0.0001) between lipid rich, fibrotic, and calcified lesions (Stary stage III: n = 2, 58 (8) Hounsfield units (HU); Stary V: n = 11, 50 (21) HU; Stary VI: n = 14, 96 (42) HU; Stary VII: n = 6, 858 (263) HU; Stary VIII: n = 18, 126 (99) HU). The concordance index kappa for the classification of plaques based on density was 0.51. Vessel dimensions had a good correlation (r = 0.98).

CONCLUSIONS

16 slice CT was found to be a reliable non-invasive imaging technique for assessing atherosclerotic plaque morphology and composition. Although calcified lesions can be differentiated from non-calcified lesions, the diagnostic accuracy in further subclassifying non-calcified plaques as lipid rich and fibrotic is low, even under experimental conditions.

Oral anticoagulant treatment: friend or foe in cardiovascular disease?

Calcification is a common complication in cardiovascular disease and may affect both arteries and heart valves. Matrix γ-carboxyglutamic acid (Gla) protein (MGP) is a potent inhibitor of vascular calcification, the activity of which is regulated by vitamin K. In animal models, vitamin K antagonists (oral anticoagulants [OACs]) were shown to induce arterial calcification. To investigate whether long-term OAC treatment may induce calcification in humans also, we have measured the grade of aortic valve calcification in patients with and without preoperative OAC treatment. OAC-treated subjects were matched with nontreated ones for age, sex, and disease. Calcifications in patients receiving preoperative OAC treatment were significantly (2-fold) larger than in nontreated patients. These observations suggest that OACs, which are widely used for antithrombotic therapy, may induce cardiovascular calcifications as an adverse side effect.

The microscopic transitional zone between elastic and muscular arteries

The microscopic transitional zone (TZ) is a segment of the arterial tree, where elastic-type wall architecture is relayed by one of muscular type. Since arterial TZ's are often sites of atherosclerotic and non-atherosclerotic lesions, this histologic anatomic substrate should be considered in the etiology and pathogenesis of vascular diseases. Herein, the topography and fine structure of TZ in renal arteries and carotid bifurcation (tripod) is described, based on randomly collected human autopsy specimens. The average length of the TZ was found to be 10 mm in the renal arteries. The TZ In the carotid tripod was localised only in the postbifurcational segments, where the length varied between 5 and more than 20 mm. In accordance with previous data from the literature, our results confirm a different ratio of scleroprotein components (elastin, collagen) and vascular smooth muscle cells (VSMC) in the microscopic TZ of arteries. Immunohistochemistry for lymphomonocytic antigens revealed no underlying inflammatory condition, especially no evidence of active cellular scavenging and an increased apoptotic rate of VSMC. We perceive the TZ as an arterial segment of reduced architectural compliance and, therefore, as a potential site of mechanotransductional failure leading to vascular diseases.

Reliability of differentiating human coronary plaque morphology using contrast-enhanced multislice spiral computed tomography: a comparison with histology

BACKGROUND

Initial clinical results indicate that multislice spiral computed tomography (MDCT) might be useful for the noninvasive characterization of human coronary plaque morphology by determining tissue density within the lesions. This seems to be of clinical relevance, because coronary artery disease might be detected at an early stage before calcifications occur and noncalcified plaques that may be more likely to rupture could also be visualized noninvasively. The aim of the present study was to evaluate the reliability of contrast-enhanced MDCT in differentiating human atherosclerotic coronary plaque morphology by comparing it with the histopathologic gold standard.

METHODS AND RESULTS

Twelve human hearts were scanned postmortem using an MDCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) high-resolution computed tomography scanner to detect atherosclerotic coronary plaques. Density measurements were performed within detected plaque areas. The exact location of each plaque was marked at the surface of the heart to assure accurate histopathologic sectioning of these lesions. The plaques were classified according to a modified Stary classification. Seventeen plaques were identified by MDCT. Six plaques were histopathologically classified as lipid rich (Stary III/IV), 6 plaques as intermediate (Stary V), and 5 plaques as calcific (Stary VII). Lipid-rich plaques had a mean density on MDCT of 42 +/- 22 Hounsfield units (HU), intermediate plaques had a mean density of 70 +/- 21 HU, and calcific plaques had a mean density of 715 +/- 328 HU. ANOVA analysis revealed a significant difference in plaque density between the 3 groups (P < 0.0001).

CONCLUSIONS

The comparison with histopathology confirms that tissue density as determined by contrast-enhanced MDCT might be used to differentiate atherosclerotic plaque morphology.

ABIN-2 forms a ternary complex with TPL-2 and NF-kappa B1 p105 and is essential for TPL-2 protein stability

NF-kappa B1 p105 forms a high-affinity, stoichiometric interaction with TPL-2, a MEK kinase essential for TLR4 activation of the ERK mitogen-activated protein kinase cascade in lipopolysaccharide (LPS)-stimulated macrophages. Interaction with p105 is required to maintain TPL-2 metabolic stability and also negatively regulates TPL-2 MEK kinase activity. Here, affinity purification identified A20-binding inhibitor of NF-kappa B 2 (ABIN-2) as a novel p105-associated protein. Cotransfection experiments demonstrated that ABIN-2 could interact with TPL-2 in addition to p105 but preferentially formed a ternary complex with both proteins. Consistently, in unstimulated bone marrow-derived macrophages (BMDMs), a substantial fraction of endogenous ABIN-2 was associated with both p105 and TPL-2. Although the majority of TPL-2 in these cells was complexed with ABIN-2, the pool of TPL-2 which could activate MEK after LPS stimulation was not, and LPS activation of TPL-2 was found to correlate with its release from ABIN-2. Depletion of ABIN-2 by RNA interference dramatically reduced steady-state levels of TPL-2 protein without affecting levels of TPL-2 mRNA or p105 protein. In addition, ABIN-2 increased the half-life of cotransfected TPL-2. Thus, optimal TPL-2 stability in vivo requires interaction with ABIN-2 as well as p105. Together, these data raise the possibility that ABIN-2 functions in the TLR4 signaling pathway which regulates TPL-2 activation.

Takayasu's arteritis secondary to myelodysplasia as a predictor of poor outcome: two case reports

We present two patients with myelodysplasia in association with Takayasu's arteritis (TA). In both patients intensive immunosuppressive treatment could not control the vascular inflammation. Subsequently both patients developed myelodysplasia, rapidly progressing to secondary acute myelogenous leukaemia. One patient had a peripheral blood stem cell transplant from a compatible sibling donor, but died of refractory leukaemia 5 months later. The other patient died of fungal sepsis. These are the first two patients reported to have TA associated with myelodysplasia/secondary leukaemia.

[Radiologic-histopathologic correlation of microcalcifications from 11g vacuum biopsy: analysis of 3196 core biopsies]

PURPOSE

To perform a statistical evaluation of microcalcifications (MC) from suspicious breast lesions detected by radiography and histopathology.

MATERIALS AND METHODS

Histological and radiological detection of calcifications were compared from 116 biopsies in 96 women. Lesions with identical description of calcifications detected in histopathology and radiography were considered concordant, patients with obvious discrepancies discordant. If histological and radiological groups of calcifications were identical in number but differed in location, the case was considered pseudo-concordant.

RESULTS

Histopathology classified 24 of 116 lesions as malignant and 92 as benign. A total of 3196 core biopsies were examined, 851 of these contained groups of calcifications or single calcifications. Both modalities detected 579 calcifications, with 169 exclusively detected by radiography and 103 exclusively by histopathology. In 35 cases (30 %) radiologic and pathologic results were concordant, in 6 cases pseudo-concordant (4 %) and in 75 cases (65 %) discordant. The case-based Kappa coefficient was - 0.09 (- 0.24 to 0.07). The 122 calcifications not detected by histopathology were few or single calcifications at the edge of the core that were probably lost during processing, 18 were possible artefacts. Six cores contained calcium oxalate, 3 contained milk of calcium. In 6 cases malignant disease was found after the first examination, hence the cores were not searched thoroughly for the missing calcifications. In the remaining 14 cases, no calcifications were found despite complete processing of the tissue. In 49 of 103 cases of radiologically undetected microcalcifications, the retrospect analysis showed dense tissue areas that probably contained the calcification. The remaining 54 cases contained calcifications, which were too small to be detected radiologically.

SUMMARY

Discordant results from pathological and radiological examinations of biopsies can mainly be explained by calcifications at the edge of the specimen lost during processing, which are therefore not detected in histopathology, and calcifications too small to be visualized radiologically.

Fibromuscular dysplasia of the renal artery responsible for renovascular hypertension: a histological presentation based on a series of 102 patients

Background: Fibromuscular dysplasia (FMD) is a rare non-atherosclerotic and non-inflammatory disease in the arterial system. The purpose of the study was a retrospective analysis of FMD in the renal artery. Patients and methods: A total number of 102 patients (mean age: 36.9 years) who suffered from renovascular hypertension underwent a surgical therapy. The operative specimens of the renal arteries were analysed with the lightmicroscop using histological and immunohistochemical methods. Results: 101 patients (99.02%) presented a medial FMD (extensive-medial subtype in 56 patients, 54.9%, subadventitial subtype in 29 patients, 28.4% and combined subtype in 16 patients, 15.7%). In 1 patient (0.98%) an adventitial FMD was found. We observed the following complications: true and dissecting aneurysms (75 patients, 74.5%), arterio-venous fistulae (2 patients, 1.96%) and chronic thrombosis (10 patients, 9.8%). Conclusions: With the progress in angioplasty, not all patients suffering from FMD undergo a primary surgical therapy and therefore this lesion is less seen in the daily work of the histopathologist.

Intrathoracic and intraabdominal locations of a cystic benign tumor: congenital etiology due to embryological diaphragm development?

A rare case of a benign cystic two-cavity tumor with intrathoracic and intraabdominal localisation is presented. The tumor's embryological etiology, embryological development of the diaphragm and the occurrence of embryonic tumors in general, are discussed. To our knowledge this is the first documented case of a benign two-cavity tumor in childhood and infancy.

Sebaceous glands in the uterine cervix: two new cases

The authors report on two new cases of sebaceous glands in the uterine cervix. This extremely rare histological observation was found on biopsy specimens of the uterine cervix because of unclear colposcopic findings and of recurrent CIN II. The etiology of this entity is discussed including a brief review of the medical literature.

CD40 regulates the processing of NF-kappaB2 p100 to p52

The nf-kb2 gene encodes the cytoplasmic NF-kappaB inhibitory protein p100 from which the active p52 NF-kappaB subunit is derived by proteasome-mediated proteolysis. Ligands which stimulate p100 processing to p52 have not been defined. Here, ligation of CD40 on transfected 293 cells is shown to trigger p52 production by stimulating p100 ubiquitylation and subsequent proteasome-mediated proteolysis. CD40-mediated p52 accumulation is dependent on de novo protein synthesis and triggers p52 translocation into the nucleus to generate active NF-kappaB dimers. Endogenous CD40 ligation on primary murine splenic B cells also stimulates p100 processing, which results in the delayed nuclear translocation of p52-RelB dimers. In both 293 cells and primary splenic B cells, the ability of CD40 to trigger p100 processing requires functional NF-kappaB-inducing kinase (NIK). In contrast, NIK activity is not required for CD40 to stimulate the degradation of IkappaBalpha in either cell type. The regulation of p100 processing by CD40 is likely to be important for the transcriptional regulation of CD40 target genes in adaptive immune responses.

Urinary bladder biopsies in spinal cord injured patients

STUDY DESIGN

A series of 94 urinary bladder biopsies in spinal cord injured (SCI) patients were histopathologically and statistically analysed.

OBJECTIVES

The following hypotheses were examined: (1) The number of clinical bladder infections per year in each patient does not influence the histopathological type of inflammation of the urinary bladder; (2) The duration of the spinal cord lesion does not have a strong effect on the type of inflammation; (3) The different neurological levels (upper and lower motor neuron lesions) do not relate to a specific histopathology.

SETTINGS

All patients received their treatment at the Swiss Paraplegic Centre in Nottwil, near Lucerne (Switzerland).

METHODS

The samples were taken from the bladder fundus during endoscopic urologic operations. Histopathological standard procedures were carried out. Statistical analysis including Kruskal-Wallis and Chi-square tests were performed.

RESULTS

Histopathological analysis showed abnormal alterations of the urinary bladder mucosa in 86 SCI-patients: (91.5%). 63 cases (67.0%) showed a chronic type and 23 cases (24.5%) showed a subacute type of inflammation. A normal urinary bladder was found in eight cases (8.5%). The three hypotheses were statistically not rejected.

CONCLUSION

Results demonstrated no correlation between the number of bladder infections per year, the period since injury, the neurologic level of the spinal cord lesion and the histopathology of the urinary bladder mucosa.

Arterial calcifications: morphological aspects and their pathological implications

Morphological aspects of calcifications are identical whatever their site in the arterial layers: fine granular deposits, plates, rings. Occurrence of complications: fibrosis with foreign body type granuloma, thrombosis, and embolism mainly depend on the site and the amount of calcification. Clinicians should be aware of these complications when performing angioplasty.

Direct phosphorylation of NF-kappaB1 p105 by the IkappaB kinase complex on serine 927 is essential for signal-induced p105 proteolysis

The p105 precursor protein of NF-kappaB1 acts as an NF-kappaB inhibitory protein, retaining associated Rel subunits in the cytoplasm of unstimulated cells. Tumor necrosis factor alpha (TNFalpha) and interleukin-1alpha (IL-1alpha) stimulate p105 degradation, releasing associated Rel subunits to translocate into the nucleus. By using knockout embryonic fibroblasts, it was first established that the IkappaB kinase (IKK) complex is essential for these pro-inflammatory cytokines to trigger efficiently p105 degradation. The p105 PEST domain contains a motif (Asp-Ser(927)-Gly-Val-Glu-Thr), related to the IKK target sequence in IkappaBalpha, which is conserved between human, mouse, rat, and chicken p105. Analysis of a panel of human p105 mutants in which serine/threonine residues within and adjacent to this motif were individually changed to alanine established that only serine 927 is essential for p105 proteolysis triggered by IKK2 overexpression. This residue is also required for TNFalpha and IL-1alpha to stimulate p105 degradation. By using a specific anti-phosphopeptide antibody, it was confirmed that IKK2 overexpression induces serine 927 phosphorylation of co-transfected p105 and that endogenous p105 is also rapidly phosphorylated on this residue after TNFalpha or IL-1alpha stimulation. In vitro kinase assays with purified proteins demonstrated that both IKK1 and IKK2 can directly phosphorylate p105 on serine 927. Together these experiments indicate that the IKK complex regulates the signal-induced proteolysis of NF-kappaB1 p105 by direct phosphorylation of serine 927 in its PEST domain.

Variable extension of the transitional zone in the medial structure of carotid artery tripod

BACKGROUND

The goal of our study was to demonstrate the extension of the transitional zone (TZ) between elastic and muscular medial structure in carotid artery tripod.

PATIENTS AND METHODS

A histologic study of 56 probes from 8 carotid artery tripods was performed. The probes were obtained from autopsies of 4 adults (mean age: 47.5 years, range 38 to 55 years) and were taken from 7 different topographic sites.

RESULTS

At each level of the CCA (at 1 cm and 2 cm proximal to the bifurcation as well as at the bifurcation) we observed an elastic arterial type in 24 (42.8%) probes with 11 to 20 (medium 15.0) elastic fibers per view field (200 x magnification) in the media. In contrast the histologic structure of the ICA and ECA varied as follows: in 8 sections (14.3%) elastic arterial type with 11 to 16 (medium 13.1) elastic fibers, in 11 sections (19.6%) muscular arterial type with 2 to 5 (medium 3.5) elastic fibers and in 9 sections (16.1%) a transitional arterial type with 6 to 8 (medium 6.7) elastic fibers in the media. Atherosclerotic lesions have prevented the assessment of the arterial type in 4 probes (7.1%). The TZ in the medial structure of carotid artery tripods is exclusively localized in the ICA/ECA but not in the CCA. The ICA/ECA presented a TZ with a length up to 0.5 cm (4 probes; 25%), up to 1.5 cm (4 probes; 25%) and longer than 1.5 cm (6 probes; 37.5%).

CONCLUSIONS

In this study we confirmed that in the carotid artery tripod, a TZ--an arterial segment with transition from elastic to muscular type--does exist, involving a variable length. Furthermore studies on the impact of the biomechanical properties of the TZ as a potential factor in atherosclerotic disease are justified. In addition, the complex biomechanical behavior of the TZ should be considered prior to interventional procedures.

Fatal myocardial infarction in a young man caused by a right megadolicho-coronary artery with thrombosis: a case report

A case of fatal myocardial infarction in a young man, secondary to thrombosis of an isolated ectatic coronary artery, is reported. Histological study of this abnormal artery demonstrated that it was of elastic type in its proximal two centimeters. This abnormal arterial structure supports the hypothesis of a congenital defect.