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Results for “excision”

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PubMed1989

Both excision and replication of cloned autonomous parvovirus DNA require the NS1 (rep) protein.

When a bacterial plasmid containing the entire genome of LuIII virus except for the terminal 18 nucleotides from the right end is transfected into HeLa cells, the viral DNA is rescued and replicated, with production of infectious virus. This experimental system was used to examine the viral proteins and cis elements required for the excision and replication of viral DNA. The deletion of the entire NS1 gene provided a viral genome that was excised from the plasmid and replicated only when an NS1 gene was provided in trans. A frameshift mutation in the NS2 intron that truncates NS1 prevented excision and replication. Deletion of the left-end terminal inverted repeat or the right-end inverted repeat prevented excision of viral DNA from that end but not from the wild-type terminus. The viral terminus excised from the plasmid was protected from a processive degradation process, which began on the vector portion of the plasmid. The inhibitor of DNA polymerases alpha and delta, aphidicolin, blocked the excision reaction.

Capsid↗

PubMed1995

An alternative eukaryotic DNA excision repair pathway.

DNA lesions induced by UV light, cyclobutane pyrimidine dimers, and (6-4)pyrimidine pyrimidones are known to be repaired by the process of nucleotide excision repair (NER). However, in the fission yeast Schizosaccharomyces pombe, studies have demonstrated that at least two mechanisms for excising UV photo-products exist; NER and a second, previously unidentified process. Recently we reported that S. pombe contains a DNA endonuclease, SPDE, which recognizes and cleaves at a position immediately adjacent to cyclobutane pyrimidine dimers and (6-4)pyrimidine pyrimidones. Here we report that the UV-sensitive S. pombe rad12-502 mutant lacks SPDE activity. In addition, extracts prepared from the rad12-502 mutant are deficient in DNA excision repair, as demonstrated in an in vitro excision repair assay. DNA repair activity was restored to wild-type levels in extracts prepared from rad12-502 cells by the addition of partially purified SPDE to in vitro repair reaction mixtures. When the rad12-502 mutant was crossed with the NER rad13-A mutant, the resulting double mutant was much more sensitive to UV radiation than either single mutant, demonstrating that the rad12 gene product functions in a DNA repair pathway distinct from NER. These data directly link SPDE to this alternative excision repair process. We propose that the SPDE-dependent DNA repair pathway is the second DNA excision repair process present in S. pombe.

Base Sequence↗

PubMed1998

Homology-dependent maternal inhibition of developmental excision of internal eliminated sequences in Paramecium tetraurelia.

Thousands of single-copy internal eliminated sequences (IESs) are excised from the germ line genome of ciliates during development of the polygenomic somatic macronucleus, following sexual events. Paramecium IESs are short, noncoding elements that frequently interrupt coding sequences. No absolutely conserved sequence element, other than flanking 5'-TA-3' direct repeats, has been identified among sequenced IESs; the mechanisms of their specific recognition and precise elimination are unknown. Previous work has revealed the existence of an epigenetic control of excision. It was shown that the presence of one IES in the vegetative macronucleus results in a specific inhibition of the excision of the same element during the development of a new macronucleus, in the following sexual generation. We have assessed the generality and sequence specificity of this transnuclear maternal control by studying the effects of macronuclear transformation with 13 different IESs. We show that at least five of them can be maintained in the new macronuclear genome; sequence specificity is complete both between genes and between different IESs in the same gene. In all cases, the degree of excision inhibition correlates with the copy number of the maternal IES, but each IES shows a characteristic inhibition efficiency. Short internal IES-like segments were found to be excised from two of the IESs when excision between normal boundaries was inhibited. Available data suggest that the sequence specificity of these maternal effects is mediated by pairing interactions between homologous nucleic acids.

Animals↗

PubMed2000

Timing of developmentally programmed excision and circularization of Paramecium internal eliminated sequences.

Paramecium internal eliminated sequences (IESs) are short AT-rich DNA elements that are precisely eliminated from the germ line genome during development of the somatic macronucleus. They are flanked by one 5'-TA-3' dinucleotide on each side, a single copy of which remains at the donor site after excision. The timing of their excision was examined in synchronized conjugating cells by quantitative PCR. Significant amplification of the germ line genome was observed prior to IES excision, which starts 12 to 14 h after initiation of conjugation and extends over a 2- to 4-h period. Following excision, two IESs were shown to form extrachromosomal circles that can be readily detected on Southern blots of genomic DNA from cells undergoing macronuclear development. On these circular molecules, covalently joined IES ends are separated by one copy of the flanking 5'-TA-3' repeat. The similar structures of the junctions formed on the excised and donor molecules point to a central role for this dinucleotide in IES excision.

Animals↗

PubMed2007

Confident complete excision of lid-margin BCCs using a marginal strip: an alternative to Mohs' surgery.

AIMS: To report a new technique of tissue preparation, using a marginal strip, after the excision of eyelid basal cell carcinomas (BCCs) and to report the long-term results of BCCs excised using this technique. METHOD: After the excision of eyelid BCC with a safety margin of 4 mm, a 1 mm strip was excised along the whole perimeter from the margin of the freshly excised specimen. This marginal strip had intact conjunctival mucosa along one edge and skin along the other. The marginal strip and the central tumour mass were then fixed immediately in formal saline and subjected to conventional histopathology. RESULTS: Of the 61 patients who completed a 5 years follow-up, the results of 28 eye-lid BCCs that were within 4 mm of the lid margin are reported. The marginal strip was clear in 22 specimens and had the presence of residual tumour in its margin in 6 specimens. These six 6 cases were further managed by observation (n = 2), by further surgical excision using marginal strip (n = 2) and by Mohs' surgery (n = 2). CONCLUSION: Marginal strip examines the entire resection margins analogous to Mohs' technique and we recommend its use in lid margin where tarsus is present throughout the specimen and >4 mm from the lid margin.

Aged↗

PubMed1997

Clinicopathological correlation of an excised choroidal neovascular membrane in pseudotumour cerebri.

AIMS/BACKGROUND: To correlate the histopathology of an excised choroidal neovascular membrane (CNV) with the clinical and angiographic findings in a 32-year-old woman with pseudotumour cerebri and a peripapillary CNV with subfoveal extension. METHODS: The patient's visual acuity was assessed by individuals experienced in low vision refraction and who were not members of the surgical team. The CNV was excised via a conventional three port vitrectomy with subretinal dissection. The excised tissue was studied with light and electron microscopy. Preoperative and serial postoperative fluorescein angiograms (FAs) and fundus photographs were obtained to study the dissection bed. RESULTS: One week after surgery, the FA showed mottled subfoveal choriocapillaris perfusion. Three weeks after surgery, this area showed retinal pigment epithelium (RPE) atrophy clinically, and the FA showed choriocapillaris non-perfusion. Six months after surgery, the area of RPE atrophy and the corresponding area of choriocapillaris non-perfusion had expanded. Histologically, the excised CNV disclosed hyperplastic RPE, fibrovascular tissue, and no choriocapillaris. Fragments of RPE basement were present along the external edge of the specimen. The patient's visual acuity did not improve significantly after surgery. CONCLUSIONS: Choriocapillaris non-perfusion can develop even in young patients following CNV excision. In this particular case, it is believed that choriocapillaris atrophy was caused by incomplete ingrowth of RPE into the dissection bed following RPE removal with CNV excision. As far as is known, this is the first report describing the results of surgery for CNV secondary to papilloedema associated with pseudotumour cerebri.

Adult↗

PubMed1995

Specimen slice radiography of cancer in breast conserving excisions.

AIM: To investigate histologically the power of specimen slice radiography to record invasive and in situ carcinoma in breast conserving cancer excisions. METHODS: Twenty six cancer excisions were converted into 171 complete tissue slices, which were examined radiographically. From these slices, 373 histological blocks were processed and histological and radiographic assessments were compared. RESULTS: Radiography and histology mapped excision margins and lesions in detail. Radiographic prediction of histology was imprecise. Six invasive carcinomas were either undetectable by radiology or reached a radiologically clear margin. Six small invasive carcinoma satellites were not recognised. Adjacent ductal carcinoma in situ was undetectable in nine of 15 cases. CONCLUSIONS: Slice radiography and histology are capable of precise lesion mapping in breast cancer excisions, and clinical utility of such mapping merits investigation. Radiology alone is imprecise and to infer complete excision of breast carcinoma by radiography (of excision specimens or residual breast) alone may be unsafe.

Breast Neoplasms↗

PubMed1998

Frequency of cervical intraepithelial neoplasia following large loop excision of the transformation zone.

AIM: To determine the frequency of cervical intraepithelial neoplasia (CIN) following large loop excision of the transformation zone of the cervix (LLETZ) according to grade and completeness of excision of CIN. METHODS: A retrospective study of 669 patients who had LLETZ biopsies showing CIN 1, 2, or 3. The patients were subdivided according to the grade and completeness of excision of CIN. The follow up period was 1.5 to 3.5 years. Risk of persistent/recurrent CIN was assessed by the frequency of histological diagnosis of CIN during the follow up period. RESULTS: Frequency of persistent/recurrent CIN increased with the grade of CIN reported: 6.7% of patients with CIN 1, 13.4% with CIN 2, and 21.7% with CIN 3 developed persistence or recurrence. The frequency of CIN persistence/recurrence was significantly lower where LLETZ showed complete excision of CIN (8.4%) than where it was incomplete (31.3%) (p < 0.0001) or equivocal (27.8%) (p < 0.0001). CONCLUSIONS: Patients with incomplete or equivocal excision of all grades of CIN merit careful, preferably colposcopic, follow up. Patients with completely excised high grade CIN require careful cervical cytologic surveillance.

Adolescent↗

PubMed1996

DNA excision repair.

In nucleotide excision repair DNA damage is removed through incision of the damaged strand on both sides of the lesion, followed by repair synthesis, which fills the gap using the intact strand as a template, and finally ligation. In prokaryotes the damaged base is removed in a 12-13 nucleotide (nt)-long oligomer; in eukaryotes including humans the damage is excised in a 24-32 nt-long fragment. Excision in Escherichia coli is accomplished by three proteins designated UvrA, UvrB, and UvrC. In humans, by contrast, 16 polypeptides including seven xeroderma pigmentosum (XP) proteins, the trimeric replication protein A [RPA, human single-stranded DNA binding protein (HSSB)], and the multisubunit (7-10) general transcription factor TFIIH are required for the dual incisions. Transcribed strands are specifically targeted for excision repair by a transcription-repair coupling factor both in E. coli and in humans. In humans, excision repair is an important defense mechanism against the two major carcinogens, sunlight and cigarette smoke. Individuals defective in excision repair exhibit a high incidence of cancer while individuals with a defect in coupling transcription to repair suffer from neurological and skeletal abnormalities.

Animals↗

PubMed1988

Effect of ureteral excision on inner medullary solute concentration in rats.

To elucidate the role of the ureter in urinary concentration we studied the effect of partial and complete ureteral excision on urinary osmolality and papillary interstitial osmolality and on sodium, potassium, and urea concentrations in the antidiuretic rat. Urine and descending vasa recta (DVR) plasma samples were obtained by micropuncture of the left renal papilla before (period 1) and 45 min after (period 2) complete (group 1, n = 10 rats) or partial (group 2, n = 10 rats) ureteral excision. Urine osmolality fell from 2,063 +/- 156 (mean +/- SE) to 736 +/- 116 mosmol/kgH2O after complete ureteral excision (P less than 0.01). After partial ureteral excision, the fall was less than half as great, from 2,038 +/- 167 to 1,551 +/- 162 mosmol/kgH2O (P less than 0.01). Vasa recta plasma osmolality decreased from 1,742 +/- 133 to 860 +/- 119 mosmol/kgH2O after complete excision (P less than 0.01) but only from 1,830 +/- 146 to 1,504 +/- 154 mosmol/kgH2O after partial excision (P less than 0.05). Mean DVR plasma sodium concentration declined from 339 +/- 25 to 211 +/- 25 meq/l (P less than 0.01) in group 1 but did not change in group 2 (348 +/- 21 to 347 +/- 28 meq/l). The fraction of DVR plasma osmolality accounted for by urea decreased significantly from 0.59 +/- 0.01 to 0.46 +/- 0.02 mM/(mosmol/kgH2O) in group 1 and from 0.59 +/- 0.02 to 0.49 +/- 0.03 mM/(mosmol/kgH2O) for group 2 (P less than 0.01, both groups). We interpret these findings to show that the remnant ureter moderates the fall in interstitial osmolality at least in part through preservation of the corticomedullary sodium chloride gradient.

Animals↗

PubMed1992

Restenosis after directional coronary atherectomy. Effects of luminal diameter and deep wall excision.

BACKGROUND: Deep wall excision during directional atherectomy has been reported in one study to increase the risk of subsequent restenosis. On the other hand, we have observed that the probability of late (6-month) restenosis is reduced by maximizing postprocedure luminal diameter. Although such maximal luminal enlargement by directional atherectomy has not increased procedural complications in our experience, it might well increase the incidence of subintimal (deep wall component) recovery. We performed this study to evaluate the relative influences of luminal enlargement and deep wall component excision on postatherectomy restenosis. METHODS AND RESULTS: Atherectomy resulted in a 7 +/- 15% residual stenosis with < 0.5% incidence of angiographic vessel perforation. The minimal luminal diameter of each lesion was measured before and after intervention in 413 lesions, 389 (94%) of which had histological analysis of the excised specimens. Specimens were categorized by the deepest layer retrieved: type I (recovery of intima alone, n = 141), type II (recovery of media, n = 79), and type III (recovery of adventitia, n = 65). Repeat angiographic measurement of minimal luminal diameter was available for 329 (80%) segments 6 months after atherectomy. Compared with the 32% restenosis rate for type I excision, there was no increase in restenosis (stenosis > 50%) for type II, type III, or types II+III (p = 0.86). Stratification by vessel characteristics also failed to show any association between restenosis and deep wall component recovery in any subgroup, including native coronary (p = 0.85), left anterior descending coronary artery (p = 0.70), right coronary artery (p = 0.51), saphenous graft (p = 0.78), or prior restenosis lesions (p = 0.98). Paradoxically, the recovery of adventitia (type III excision) was associated with a lower late percent stenosis (p = 0.03) and a trend toward less restenosis (p = 0.11) compared with type I excisions. A multiple logistic regression model was constructed that demonstrated immediate postprocedure luminal diameter (p = 0.02) to be an independent determinant of restenosis. In this model, the presence of deep wall components (type II+III) did not adversely affect (p = 0.86) restenosis, but the recovery of adventitia was associated with an independent trend toward reduced restenosis (p = 0.06). CONCLUSIONS: The immediate goal of directional atherectomy should be to safely provide the largest lumen possible in order to reduce restenosis. The recovery of deep wall components does not appear to jeopardize the beneficial effect that obtaining a large immediate postprocedure lumen diameter has on reducing the incidence of late restenosis.

Atherectomy, Coronary↗

PubMedDate not supplied

Effect of electrical stimulation on arteriogenesis and angiogenesis after bilateral femoral artery excision in the rabbit hind-limb ischemia model.

The effects of electrical stimulation (ES) on arteriogenesis (the opening of preexisting collaterals) and angiogenesis (formation of new capillaries) were studied after acute bilateral hind limb ischemia was induced via bilateral femoral artery excision in a rabbit model. The study evaluated the rabbit hind limbs' normal response to acute ischemia and to application of ES by calculating changes in arterial and capillary densities. Comparisons were made with our prior study, in which the femoral artery was unilaterally excised, as we attempted to expand on the topics of arteriogenesis and angiogenesis. Twelve adult New Zealand white rabbits were randomly assigned to 1 of 2 series. In Series 1, the control group, both femoral arteries were excised and no ES was applied. In Series 2, both femoral arteries were excised and ES was applied to the left limb. One lead was implanted into the left adductor muscle near the site of the excised left femoral artery (Series 2), and a stimulator (Thera, Medtronic, Inc, Minneapolis, MN) was implanted in a separate pocket. ES was applied at a rate of 3 V, 30 contractions per minute, beginning immediately after surgery and continuously for 1 month. Angiography was performed in all 12 rabbits 1 month after surgery to establish the anatomy of the collateral vessels and to demonstrate that the femoral artery stump continued to be an end artery. Contrast-opacified arteries (COAs) that crossed the grid's midline, and the total number of grid lines intersected by COAs, were tallied according to an established method. Capillary density was calculated as the number of capillaries per square millimeter of muscle. In Series 1, after 1 month, the number of COAs crossing the grid's midline was 4.5 +/-1.5 on the left and 4.8 +/-1.2 on the right side. In Series 2, the number of COAs crossing the grid's midline was 7.9 +/-1.8 on the left side (p<0.05 vs Series 1) and 5.9 +/-1.6 on the right side of the same rabbit (p=NS vs Series 1). In Series 1, 36.7 +/-5.4 and 30.5 +/-7.7 total intersections were crossed by COAs on the left and right sides, respectively. In Series 2, total grid intersections crossed by COAs were 48.4 +/-8.5 and 47.5 +/-9.1 in the left and right sides, respectively (p<0.001 vs series 1). Baseline capillary density before femoral artery excision was 180.2 +/-21.3/mm(2). The capillary densities on the left sides were 94.2 +/-19.1 and 264.5 +/-7.6 in Series 1 and 2, respectively (p<0.001). The right sides showed a similar pattern with capillary densities of 88.5 +/-37.2 and 135.8 +/-6.8 (p<0.05) in Series 1 and 2, respectively. When capillary density was compared on the left and right sides of the same rabbit in Series 2, a statistically significant increase was also found; 264.5 +/-7.6 vs 135.8 +/-6.8 (p<0.001) in the left and right sides, respectively. Comparisons of the effect of electrical stimulation and the body's normal physiologic response to acute ischemia revealed a significant increase in the opening of preexisting collaterals (arteriogenesis) and the promotion of capillary density (angiogenesis) with the use of electrical stimulation.

Angiography↗

PubMed2001

Validation of peripheral dual-energy X-ray absorptiometry for the measurement of bone mineral in intact and excised long bones of rats.

We evaluated the precision and accuracy of peripheral dual-energy X-ray absorptiometry (DXA) for the measurement of bone mineral density (BMD) and bone mineral content (BMC) in intact and excised femurs and tibias from rats. Thirty-one Sprague-Dawley rats (18F/13M; 114-360 g) were used in the study. Precision and accuracy were determined in 23 rats and prediction equations were evaluated in an independent sample of 8 animals. Precision was determined by measuring the right hindquarter three times with repositioning between scans. The femur and tibia were then excised, cleaned, and scanned in triplicate, with repositioning. CVs ranged from 0.66 to 2.24%. Accuracy of BMC was determined by comparison to bone ash values. BMC values for the intact and excised femur significantly overestimated bone ash (p < 0.001) by 33% and 5.5%, respectively. BMC for the intact tibia overestimated ash by 37% (p < 0.001), whereas BMC for the excised tibia underestimated ash by 1% (p < 0.05). However, BMC and bone ash were highly related for both bones, whether BMC was measured in the intact animal or after excision (r2 > 0.99). Cross-validation of prediction equations in an independent sample showed that there were no significant differences between predicted ash (based on BMC from DXA) and measured bone ash. These results suggest the peripheral DXA is a useful tool for measuring intact and excised rat leg bones.

Absorptiometry, Photon↗

PubMed2006

The influence of natural substrates and inhibitors on the nucleotide-dependent excision activity of HIV-1 reverse transcriptase in the infected cell.

Human immunodeficiency virus type 1 resistance to nucleoside reverse transcriptase inhibitors such as 3'-azido-2', 3'-dideoxythymidine (AZT) can arise through mutations in the coding region of reverse transcriptase (RT) that enhance the enzyme's ability to remove the drug after it has been incorporated. This excision activity of HIV-1 RT has been well characterized in a number of in vitro systems. However, the in vitro findings do not provide a complete picture of the in vivo significance of this resistance mechanism. This review will attempt to bridge the gap between the in vitro observations and the in vivo environment by summarizing the fragmentary information that is available about the intracellular conditions that may influence drug excision in cell subpopulations that are infected by HIV-1. Topics that will be discussed include (a) intracellular compounds HIV-1 RT may use to remove chain terminators; (b) how dNTPs can affect excision activity and how these effects differ in different immune cell subpopulations; (c) the influence of HIV infection on excision activity--e.g., through immune activation of infected cells or through changes indirectly induced in cells that subsequently become infected; (d) intracellular conditions that favor selection for mutations that increase the excision-based resistance mechanism; (e) the importance of macrophages in the selection of resistance mutations. Understanding factors that control excision in the intracellular environment will greatly enhance our understanding of the process of selection for this class of drug resistance mutations and may open doors for the development of novel targets for antiviral therapy.

DNA Repair↗

PubMed2004

High-resolution MRI of the anatomy important in total mesorectal excision of the rectum.

OBJECTIVE: The surgical removal of a rectal carcinoma and the adjacent lymph nodes in an en bloc package lessens the risk of local recurrence due to residual tumor. Heightened awareness of good surgical techniques has created much interest in the anatomy involved in total mesorectal excision surgery, with particular focus on the fascial planes and nerve plexuses and their relationship to the surgical planes of excision. Clear preoperative depiction of these relationships is of value in determining tumor resectability. The aim of this study was to describe the radiologic appearance of these anatomic structures. SUBJECTS AND METHODS. High-spatial-resolution T2-weighted MRI was performed using a 1.5-T system in cadaveric sections and in patients before they underwent total mesorectal excision surgery. Anatomic dissections of sagitally sectioned hemipelves were compared with MRIs obtained in vivo to establish criteria for visualization of the structures relevant to anterior resection of the rectum. RESULTS: High-spatial-resolution MRI depicted a number of structures of importance in total mesorectal excision surgery. The mesorectal fascia, which forms the boundary of the surgical excision plane in total mesorectal excision, was identified, and the presacral fascia, peritoneal reflection, and Denonvilliers' fascia were also shown. Structures 1-2 mm in diameter were visualized because the contrast resolution afforded by T2-weighted fast spin-echo imaging permitted depiction of the inferior hypogastric nerve plexus and the fascial planes within the posterior pelvis. CONCLUSION: Anatomic landmarks important to the performance of rectal cancer surgery, in particular the mesorectal fascia, may be defined on MRI and are of potential importance in the staging of tumors, assessing resectability, planning surgery, and selecting patients for preoperative neoadjuvant therapy.

Aged↗

PubMed2006

Effects of femur position on radiographic assessment of completeness of femoral head and neck excision in medium- to large-breed dogs.

OBJECTIVE: To determine the effect of femur positioning on radiographic assessment of completeness of excision after femoral head and neck excision (FHNE) in medium to large breed dogs. SAMPLE POPULATION: 10 femurs from canine cadavers (body weight > 20 kg). PROCEDURE: Complete FHNE was performed on 5 canine femurs. Excision consisting of inadequate removal of the medial distal aspect of the femoral neck was performed on the remaining 5 femurs. Each femur was positioned with predetermined amounts of internal and external rotation about the long axis and radiographed. Investigators evaluated a set of 8 radiographic views of each femur. Sensitivity (SE), specificity (SP), positive predictive value, negative predictive value, and completeness of excision assessment accuracy were estimated for each of the femur positions. RESULTS: Craniocaudal radiographic views of the femur positioned with external rotation of 15 degrees, 30 degrees, and 45 degrees as a group had the highest SE, SP, and completeness of excision assessment accuracy relative to other radiographic views. The SE, SP, and accuracy of assessment were higher when the degree of external rotation was increased from 15 degrees to 30 degrees or 45 degrees. CONCLUSIONS AND CLINICAL RELEVANCE: Craniocaudal radiographic views of the femur positioned in external rotation (15 degrees, 30 degrees, and 45 degrees) improved the ability to detect adequacy of excision relative to standard craniocaudal and lateromedial radiographic views. Evaluation of craniocaudal radiographic views of the femur positioned in external rotation may increase the ability to assess FHNE adequacy in medium- to large-breed dogs.

Animals↗

PubMed2004

Evaluation of surgical margins required for complete excision of cutaneous mast cell tumors in dogs.

OBJECTIVE: To determine whether neoplastic mast cells extended into tissue 1, 2, or 3 cm laterally or deeper than 1 fascial plane from the visible edge of cutaneous mast cell tumors (MCTs) in dogs. DESIGN: Prospective study. ANIMALS: 21 client-owned dogs with > or = 1 cutaneous MCT PROCEDURES: After preparation for surgery, each dog's skin was marked 1, 2, and 3 cm from the tumor edge at 0 degrees, 90 degrees, 180 degrees, and 270 degrees. At each 3-cm mark, deep fascia was exposed and sutured to the skin; the tumor was excised in routine fashion and fixed in formalin. Tumors were graded; margins were examined histologically for neoplastic mast cells. RESULTS: 23 cutaneous MCTs in 21 dogs were included in this study. Fifteen (65%) tumors were located on the trunk, 5 (22%) on the hind limbs, and 3 (13%) on the head and neck. There were 3 (13%) grade-I and 20 (87%) grade-II tumors. All grade-I tumors were completely excised at all margins. Seventy-five percent of the grade-II tumors were completely excised at the 1-cm margin, and 100% were completely excised at the 2-cm margin. Two grade-II MCTs located on the hind limbs of dogs were excised with a complete but close (within 1 mm) deep margin. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a 2-cm lateral margin and a deep margin of 1 fascial plane appear to be adequate for complete excision of grade-I and -II MCTs in dogs.

Animals↗

PubMed2006

Evaluation of a two-centimeter lateral surgical margin for excision of grade I and grade II cutaneous mast cell tumors in dogs.

OBJECTIVE: To evaluate completeness of excision and clinical outcome in dogs with cutaneous mast cell tumors (MCTs) excised with a lateral margin of 2 cm and a deep margin of 1 fascial plane. DESIGN: Prospective study. ANIMALS: 16 client-owned dogs with 1 or more cutaneous MCTs. PROCEDURE: Excision of MCTs was performed with a 2-cm lateral margin and a deep margin of 1 fascial plane. Histologic tumor grading was performed; surgical margins were categorized as complete or incomplete. Follow-up information was obtained via repeat examination of the dogs by veterinarians or client-completed questionnaires. RESULTS: 4 grade I and 19 grade II cutaneous MCTs were evaluated. Overall, 21 (91%) MCTs were completely excised; 2 grade II tumors had foci of mast cells at the 2-cm margin. Two dogs received adjunctive treatments following surgery. Follow-up information was available for all dogs (median follow-up period, 379 days; range, 51 to 538 days); no local recurrence was detected during this time. De novo MCTs were detected in 3 of 16 dogs at 37, 54, and 154 days after surgery. Via Kaplan-Meier analysis, median survival time and disease-free interval were both > 538 days (medians not yet reached). No prognostic variables were identified. CONCLUSIONS AND CLINICAL RELEVANCE: Excision with a 2-cm lateral margin and a deep margin of 1 fascial plane may result in satisfactory excision of grades I and II MCTs in dogs, with recurrence rates similar to those reported previously. Use of these margins may minimize complications associated with larger local tumor resection.

Animals↗