Routine early laparoscopic cholecystectomy for acute cholecystitis after conclusion of a randomized controlled trial

Background

The aim of this retrospective review was to assess the clinical outcomes of laparoscopic cholecystectomy for acute cholecystitis since the conclusion of a randomized controlled trial in 1997.

Methods

Records of all patients admitted for acute cholecystitis in whom early laparoscopic cholecystectomy was attempted between July 1997 and December 2004 were reviewed.

Results

A total of 209 patients were recruited to this study. Forty-three surgeons performed the procedures. The conversion rate increased significantly in the early period after the trial from 21 per cent to 42 per cent (39 of 92 patients) and decreased significantly to 24 per cent (13 of 54 patients) in the later period. The proportion of operations performed by higher surgical trainees increased significantly from 17 per cent in the early period to 56 per cent in the later period. This increase was associated with a fall in conversion rate without any significant increase in duration of operation or complication rate.

Conclusion

This study has demonstrated that the results achieved in a randomized trial can be translated into clinical practice by the entire surgical unit. A structured training programme with the inclusion of an experienced surgeon assisting both trainees and specialists should minimize this learning curve.

Single nucleotide polymorphism in the promoter region of human alpha-fetoprotein (AFP) gene and its significance in hepatocellular carcinoma (HCC)

BACKGROUND

Variations of serum AFP levels in HCC patients and cell lines are likely due to the differential activity of enhancer/silencer elements that control AFP. To understand the potential mechanism underlying the differential expression of AFP, we have examined the sequence of the AFP promoter in HCC.

METHODS

Direct DNA sequencing was carried out to sequence 980 bp of AFP promoter of DNA samples isolated from 83 HCC patients.

RESULTS

Three novel SNPs in the promoter region of the AFP gene, which have not been previously reported, were found at positions -330, -401 and -692. The level of serum AFP was significantly higher in HCC patients with the CT genotype of 330 SNP or the AG genotype of the 401 SNP. The genotype of CG in 692 SNP was also associated with a significant elevated level of serum AFP, and further this genotype appeared to be associated with the high risk of HCC development. 401 SNP and 692 SNP were located at the positions of known binding sites for transcription factors that have a role in the production of AFP and the growth of tumors.

CONCLUSIONS

The novel polymorphisms identified in the promoter region of the AFP gene may be pathologically significant in HCC.

Vascular defect beyond the endothelium in type II diabetic patients with overt nephropathy and moderate renal insufficiency

There is a paucity of data on the effects of overt nephropathy and moderate renal impairment on endothelial function in diabetic patients. A total of 26 type II diabetic (DM) patients with nephropathy (DMN+) (mean +/- s.d. age: 63.7 +/- 6.3 years), 32 diabetic patients without nephropathy (DMN-) (59.4 +/- 10.1 years), and 52 non-diabetic subjects (54.9 +/- 8.2 years) were recruited. High-resolution ultrasound scan was used to measure carotid intima media thickness (IMT) and flow-mediated dilation (FMD) of the brachial artery. Endothelium-independent dilation was determined by maximal vascular dilation after sublingual nitroglycerine (glyceryl trinitrate (GTN)-induced dilation). The mean carotid IMT increased progressively from non-DM to DMN- to DMN+ groups (0.74 +/- 0.23 vs 0.80 +/- 0.25 vs 1.03 +/- 0.38 mm; P=0.001 for trend) whereas FMD- (4.3 +/- 2.5 vs 3.9 +/- 1.7 vs 1.9 +/- 2.0%, P<0.001 for trend) and GTN-induced dilation (14.7 +/- 4.0 vs 14.5 +/- 3.9 vs 10.3 +/- 3.2%; P<0.001 for trend) declined in an opposite manner. On multivariate analysis, age (beta=0.257, P=0.009), glomerular filtration rate (beta=-0.364, P<0.001), and smoking (beta=0.25, P=0.013) were independently associated with carotid IMT (F=15.76, R(2)=0.340, P<0.001). After adjustment for baseline brachial arterial diameter, history of smoking (beta=-0.039, P<0.001), fasting plasma glucose (beta=-0.033, P=0.002), and total cholesterol (beta=-0.023, P=0.024) were independently associated with vessel diameter after FMD (F=2446.5, R(2)=0.992, P<0.001); whereas age (beta=-0.069, P=0.001) and urinary albumin excretion (beta=-0.048, P=0.018) were independently associated with vessel diameter after GTN (F=851.6, R(2)=0.967, P<0.001). Type II diabetic patients with overt nephropathy and moderate renal impairment had both structural and functional vascular abnormalities beyond the endothelium.

Biliary Cystadenoma and Other Complicated Cystic Lesions of The Liver: Diagnostic and Therapeutic Challenges

INTRODUCTION

Biliary cystadenomas are complicated cystic lesions of the liver. They are rare and pose considerable diagnostic and therapeutic challenges.

METHODS

We present our experience managing these lesions by performing a retrospective review of all patients with a preoperative diagnosis of or histologically proven biliary cystadenoma who underwent surgery between January 1995 and January 2005 at our institution. Altogether, 20 patients (16 women, 4 men) with a mean age of 58 years underwent a total of 22 operations. The diagnosis of biliary cystadenoma was based on exclusion of other pathologic entities and the presence of radiologic characteristics of biliary cystadenoma. Abdominal ultrasonography (US), computed tomography, or both were performed in all patients. US-guided fine-needle aspiration cytology was performed in seven patients and all of them were negative for malignancy. A preoperative diagnosis of biliary cystadenoma was made in 16 patients based on clinical and radiologic features and was correct in 6 of them. Diagnosis of biliary cystadenoma was not suspected in four patients.

RESULTS

The overall diagnostic accuracy was 30%. Enucleation was the most common surgical procedure and was performed in 10 patients. The mean follow-up period was 5.5+/-2.8 years. No recurrence was detected in patients with confirmed biliary cystadenoma after adequate excision.

CONCLUSIONS

The findings of this study highlight the difficulty with preoperative diagnosis of biliary cystadenoma, which has seldom been discussed in the literature. Preoperative differentiation by means of radiologic imaging is inaccurate (30%). Any therapy short of complete excision leads to local recurrence and risk of malignant transformation. Complete excision of any suspicious lesion remains the best method of diagnosis and treatment.

MicroAlbuminuria Prevalence Study (MAPS) in hypertensive type 2 diabetic patients in Hong Kong

OBJECTIVES

To assess the prevalence of macroalbuminuria and microalbuminuria, and the level of blood pressure control in patients with type 2 diabetes and hypertension in Hong Kong.

DESIGN

Cross-sectional clinic-based epidemiological study.

SETTING

Six medical centres (including two public hospital diabetes centres) in Hong Kong.

PATIENTS

Recruited from the medical centres from April to November 2002, after excluding those with bacteriuria and haematuria.

MAIN OUTCOME MEASURES

Body mass index; blood pressure; levels of blood glucose, macroalbuminuria, and microalbuminuria; treatments for hypertension and diabetes.

RESULTS

The as per-protocol recruited population of 437 hypertensive type 2 diabetic patients had a mean age of 61.7 (standard error, 0.5) years. Overall, the prevalence of diabetic nephropathy in this population was high; 18.3% had macroalbuminuria (95% confidence interval, 16.5-20.2%) and 24.9% had microalbuminuria (95% confidence interval, 22.9-27.0%). Predictive factors were advanced age, male sex, poor blood pressure control, and existing cardiovascular complications. Whilst almost all patients (96.1%) were receiving treatment for hypertension, only 25.6% had systolic/diastolic blood pressures below the 130/85 mm Hg target.

CONCLUSIONS

In Hong Kong, the prevalence of microalbuminuria and macroalbuminuria is high in type 2 diabetic patients with hypertension, particularly in males and those with poorly controlled systolic blood pressure. Tight glycaemic control, antihypertensive therapy, and use of renin-angiotensin system inhibitors/blockers are necessary to retard the progression of nephropathy to advanced renal disease.

Fatal septicaemia from Chromobacterium violaceum: case reports and review of the literature

Chromobacterium violaceum rarely causes infection in humans and its mechanism of pathogenicity is not well understood. Human infection carries a high mortality rate with a fulminating clinical progression. A high index of suspicion is required for diagnosis, and is based on recovering the organisms from blood cultures or other appropriate specimens. We present three cases of human infection managed in a tertiary referral hospital in Hong Kong with a review of the literature.

Emergency laparoscopic unroofing of a ruptured hepatic cyst

The use of laparoscopic techniques in the emergency treatment of liver cyst complications has not been reported in the literature. Laparoscopic surgery is a well-established treatment modality for giant hepatic cyst in the elective setting. We report a case of laparoscopic unroofing of a 15-cm ruptured hepatic cyst, which had recurred after previous percutaneous alcohol instillation therapy. Laparoscopic ultrasound was used to delineate the extent of the cyst while a Harmonic scalpel was used for dissection. The patient made an uneventful recovery and was discharged 4 days after the operation.

Tuberculous peritonitis in a haemodialysis patient with elevated serum CA 125 and hypercalcaemia

CA 125, a glycoprotein derived from coelomic epithelium, is used primarily as a marker of epithelial ovarian cancer. However, elevated levels of serum CA 125 have also been detected in other benign and malignant disorders. This study describes a haemodialysis patient who contracted tuberculous peritonitis associated with hypercalcaemia, erythropoietin-resistant anaemia and elevated CA 125, which normalised gradually following antituberculosis treatment. Tuberculous peritonitis should be considered in the differential diagnosis of ascites with elevated serum CA 125. Additionally, CA 125 is a useful marker for monitoring response to tuberculous peritonitis treatment.

Granulocytic sarcoma of the small bowel causing intestinal obstruction

Granulocytic sarcomas of the small bowel are rare. They are discrete tumours of leukaemic myeloblasts and partially matured granulocytes that form in any part of the body. This disease is infrequently seen in patients with acute myeloid leukaemia, and rarely seen in patients without leukaemia. Here we report a case of small bowel obstruction due to granulocytic sarcoma of mid-ileum in a non-leukaemic patient. We also review the literature on treatment and prognosis of this condition.

Embryotrophic factor-3 from human oviductal cells enhances proliferation, suppresses apoptosis and stimulates the expression of the β1 subunit of sodium–potassium ATPase in mouse embryos

BACKGROUND

Embrytrophic factor-3 (ETF-3) from human oviductal cells enhanced the development of mouse preimplantation embryos. This report studied the embryotrophic mechanisms of the molecule.

METHODS AND RESULTS

Mouse embryos were incubated with ETF-3 for 24 h at different stages of development. ETF-3 treatment between 96 and 120 h post-HCG increased the cell count of blastocysts, whilst treatment between 72 and 96 h post-HCG enhanced the expansion and hatching of the blastocysts. ETF-3 increased the cell number of the embryos by suppressing apoptosis and increasing proliferation as determined by TUNEL and bromodeoxyuridine uptake assays, respectively. Real-time quantitative PCR showed that the in vivo developed and ETF-3-treated blastocysts had a significantly higher mRNA copy number of Na/K-ATPase-beta1, but not of hepsin, than that of blastocysts cultured in medium alone. The former gene was associated with cavitation of blastocysts while the latter was related to hatching of blastocyst. The beneficial effect of ETF-3 on blastocyst hatching was also seen when ETF-3-supplemented commercially available sequential culture medium for human embryo culture was used to culture mouse embryos.

CONCLUSIONS

ETF-3 improves embryo development by enhancing proliferation, suppressing apoptosis and stimulating expression of genes related to blastocyst cavitation. Supplementating human embryo culture medium with ETF-3 may improve the success rate in clinical assisted reproduction.

Establishment of a capillary-cumulus model to study the selection of sperm for fertilization by the cumulus oophorus

BACKGROUND

Spermatozoa have to traverse the cumulus oophorus before fertilization in vivo. Evidence suggests that the cumulus oophorus plays an important role in the fertilization process. We describe the establishment of a capillary-cumulus oophorus model with which to study the action of cumulus mass on the function of human spermatozoa.

METHODS

Human cumulus oophorus was aspirated into a glass capillary. Spermatozoa were allowed to pass through the cumulus mass in the capillary from one end of the capillary. The spermatozoa that had traversed the mass were collected at the other end of the capillary and underwent sperm function analyses.

RESULTS

Compared with those spermatozoa cultured in medium alone, spermatozoa exposed to the cumulus mass were more likely to have normal morphology, be capacitated and acrosome reacted, with a distinct motility pattern and better zona-binding capacity.

CONCLUSION

A novel in vitro model for spermatozoa penetration through the cumulus oophorus was established. The model can be applied to investigate the effect of the cumulus oophorus on sperm functions.

The Contribution of d-Mannose, l-Fucose, N-Acetylglucosamine, and Selectin Residues on the Binding of Glycodelin Isoforms to Human Spermatozoa1

Previous data showed that glycodelin-A from amniotic fluid and glycodelin-F from follicular fluid inhibited sperm-zona pellucida binding. Solubilized zona pellucida reduced the binding of glycodelin-F to sperm extract dose dependently. This study demonstrated that the zona pellucida proteins also reduced the binding of glycodelin-A to sperm extract. Ionophore-induced acrosome reaction reduced the binding of iodinated glycodelin-A and -F to sperm, indicating that the glycodelin-binding sites are on the outer acrosomal membrane or on the sperm plasma membrane overlying the acrosome. While the binding of glycodelin-A to sperm was suppressed by mannose and fucose neoglycoproteins, that of glycodelin-F was also reduced by acetylglucosamine neoglycoprotein. Pretreatment of sperm with inhibitors of mannosidase and acetylglucosaminidase reduced the binding of glycodelin-F to sperm. On the other hand, inhibitor of mannosidase but not of acetylglucosaminidase inhibited the binding of glycodelin-A. In a competition binding assay, mannosidase reduced both glycodelin-A and -F binding whereas acetylglucosaminidase reduced only glycodelin-F binding. While fucosidase reduced the binding of both glycodelins, fucosidase inhibitor was marginally active in suppressing the binding of glycodelins to human sperm. Among the selectins tested, only E-selectin had a slight inhibitory effect on the binding of glycodelin-A to sperm. The binding of glycodelin-F was unaffected by selectins and their antibodies. In conclusion, the binding of glycodelin-A to sperm involves mannose, fucose, and possibly E- selectin residues, while that of glycodelin-F involves mannose, fucose, and N-acetylglucosamine but not the selectin residue.

Consensus statement on iodine deficiency disorders in Hong Kong

This article reviews the available data on the study of iodine deficiency disorders in Hong Kong and to discuss the approach towards preventing such disorders in Hong Kong. The importance of iodine and iodine deficiency disorders is described, and the available data on the dietary iodine intake and urinary iodine concentration in different populations of Hong Kong are summarised and discussed. Dietary iodine insufficiency among pregnant women in Hong Kong is associated with maternal goitrogenesis and hypothyroxinaemia as well as neonatal hypothyroidism. Borderline iodine deficiency exists in the expectant mothers in Hong Kong. Women of reproductive age, and pregnant and lactating women should be made aware and educated to have an adequate iodine intake, such as iodised salt, as an interim measure. A steering group involving all stakeholders should be formed to advise on the strategy of ensuring adequate iodine intake, including universal iodisation of salt in Hong Kong. Continuous surveillance of iodine status in the Hong Kong population is necessary.

Identification of novel genes expressed during spermatogenesis in stage-synchronized rat testes by differential display

The molecular mechanism regulating spermatogenesis at different developmental stages remains largely unknown. In a vitamin A-deficiency (VAD) rat model, five distinct histologically defined, stage-synchronized testes: (i) resting spermatogonia and preleptotene spermatocytes at Day 0 of post-vitamin A treatment (PVA); (ii) early pachytene spermatocytes at Day 7 PVA; (iii) late pachytene at Day 15 PVA; (iv) round spermatids at Day 25 PVA; and (v) elongated spermatids at Day 35 PVA were used to study gene expression profiles by mRNA differential display. Twenty-four differentially expressed cDNA fragments were identified and cloned; oligonucleotide sequence analyses indicated that there are 12 novel gene sequences, half of which share no apparent match in current GenBank/EMBL databases. Other 12 VAD clones share sequence homology to membrane channel and transport, transcription and translation, cell cycle and morphogenesis, inducer and transducer, surface or secreted glycoproteins or enzymes, and other miscellaneous molecules. Semi-quantitative RT-PCR analyses against different stages of VAD testes demonstrated: (i) restricted expression of VAD1.2 and 1.3 (novel) on Day 25 PVA when round spermatids form; (ii) escalating pattern of VAD12 (Cx43) in Sertoli cells; and (iii) relative constant levels of VAD4 (A5D3), VAD26.1 (ribonuclease), and VAD27 (GRP8) in spermatogenesis.

Zona-binding inhibitory factor-1 from human follicular fluid is an isoform of glycodelin

Zona-binding inhibitory factor-1 (ZIF-1), a glycoprotein in human follicular fluid, reduces the binding of spermatozoa to the zona pellucida. ZIF-1 has a number of properties similar to those of glycodelin-A from human follicular fluid. The objective of this study was to compare the biochemical characteristics of these two glycoproteins. N-terminal sequencing and protease-digested peptide mapping showed that ZIF-1 and glycodelin-A have the same protein core. However, these glycoproteins differ in their oligosaccharide chains, as demonstrated by fluorophore-assisted carbohydrate electrophoresis, lectin-binding ability, and isoelectric focusing. ZIF-1 inhibited spermatozoa-zona pellucida binding slightly more than did glycodelin-A and significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. Indirect immunofluorescence staining revealed specific binding of glycodelin-A and ZIF-1 to the acrosome region of human spermatozoa, where ZIF-1 produced a stronger signal than did glycodelin-A at the same protein concentration. These data suggest that ZIF-1 is a differentially glycosylated isoform of glycodelin that potently inhibits human sperm-egg interaction. Future study on the function role of ZIF-1 would provide a better understanding of the regulation of fertilization in humans.

Embryotrophic factor-3 from human oviductal cells affects the messenger RNA expression of mouse blastocyst

Our previous results showed that embryotrophic factor-3 (ETF-3) from human oviductal cells increased the size and hatching rate of mouse blastocysts in vitro. The present study investigated the production of ETF-3 by an immortalized human oviductal cell line (OE-E6/E7) and the effects of ETF-3 on the mRNA expression of mouse embryos. The ETF-3 was purified from primary oviductal cell conditioned media using sequential liquid chromatographic systems, and antiserum against ETF-3 was raised. The ETF-3-supplemented Chatot-Ziomek-Bavister medium was used to culture Day 1 MF1 x BALB/c mouse embryos for 4 days. The ETF-3 treatment significantly enhanced the mouse embryo blastulation and hatching rate. The antiserum, at concentrations of 0.03-3%, abolished the embryotrophic effect of ETF-3. Positive ETF-3 immunoreactivity was detected in the primary oviductal cells, OE-E6/E7, and blastocysts derived from ETF-3 treatment. Vero cells (African Green Monkey kidney cell line), fibroblasts, and embryos cultured in control medium did not possess ETF-3 immunoreactivity. The mRNA expression patterns of the treated embryos were studied at the blastocyst stage by mRNA differential display reverse transcription-polymerase chain reaction (DDRT-PCR). The DDRT-PCR showed that some of the mRNAs were differentially expressed after ETF-3 treatment. Twelve of the differentially expressed mRNAs that had high homology with cDNA sequences in the GenBank were selected for further characterization. The differential expression of seven of these mRNAs (ezrin, heat shock 70-kDa protein, cytochrome c oxidase subunit VIIa-L precursor, proteinase-activated receptor 2, eukaryotic translation initiation factor 2beta, cullin 1, and proliferating cell nuclear antigen) was confirmed by semiquantitative RT-PCR. In conclusion, immortalized oviductal cells produce ETF-3, which influences mRNA expression of mouse blastocyst.

Submandibular Castleman's disease

Castleman's disease is a rare benign lymphoid tumour of unknown aetiology, which usually appears as a solitary mediastinal mass. We report an unusual case of Castleman's disease, an asymptomatic submandibular mass in the lower jaw, and we discuss the computed tomography appearance.

Glycohaemoglobin measurement: methodological differences in relation to interference by urea

The aim of this study was to investigate the agreement between a cation-exchange HPLC method and a boronate affinity method of measuring glycohaemoglobin (HbA1c), with particular reference to the effect of elevated urea concentration. HbA1c was measured by both methods in samples from 75 subjects who were classified as diabetic with normal (n=36) or abnormal (n=12) renal function, and non-diabetic with normal (n=8) or abnormal (n=19) renal function. Urea was found to cause a clinically significant interference in the HPLC method at a level > or =17.0 mmol/l. Each increase of 1 mmol/l urea in serum was associated with an absolute increase of 0.04% in the HbA1c value as measured by the HPLC method. The boronate affinity method for HbA1c did not appear to be affected by elevated urea concentration. There was significant correlation (r=0.97, p<0.001) between HbA1c results obtained by the two methods, however, results obtained by the boronate affinity method were generally lower. The discrepancy between results obtained by the two methods was particularly marked in uraemic samples from diabetic subjects, as the HPLC/boronate affinity difference increased as the HbA1c increased and also as the urea concentration increased. Results indicate that blood from diabetic patients with renal failure may give erroneously high HbA1c values by HPLC. Results also highlight the importance of choosing appropriate clinical samples and statistical techniques when evaluating or comparing test methods.

Experimental simulation of two-particle quantum entanglement using classical fields

We experimentally demonstrate simulation of two entangled quantum bits using classical fields of two frequencies and two polarizations. Multiplication of optical heterodyne beat signals from two spatially separated regions simulates coincidence detection of two particles. The product signal so obtained contains several frequency components, one of which can be selected by bandpass frequency filtering. The bandpassed signal contains two indistinguishable, interfering contributions, permitting simulation of four polarization-entangled Bell-like states. These classical field methods may be useful in small scale simulations of quantum logic operations that require multiparticle entanglement without collapse.

Laparoscopic repair of morgagni's hernia with percutaneous placement of suture

Simultaneous laparoscopic repair of Morgagni's hernia and laparoscopic cholecystectomy in a 59-year-old lady is described. In contrast to most previous reported series, in which repairs were fashioned with direct intracorporeal suturing, stapling, or mesh placement, an alternative technique of suture placement with a percutaneously inserted needle was applied. The procedure was smooth, and there was no evidence of recurrent hernia 9 months after the operation.

The synthesis and fate of glycodelin in human ovary during folliculogenesis

The ontogeny of glycodelin in human ovarian follicles during folliculogenesis was studied. Glycodelin immunoreactivity began to be detected in the granulosa cells and thecal cells of late secondary follicles. Immunoreactivity was also found in both the luteinized granulosa cells and cumulus cells obtained from women undergoing the assisted reproduction treatment. However, only the luteinized granulosa cells, and not the cumulus cells, expressed glycodelin mRNA. Results also showed that the cumulus cells took up radiolabelled glycodelin and partially deglycosylated some of it. Glycodelin (and a partially deglycolsylated form of glycoldelin) appeared to complex with two cytoplasmic or membrane components of the cumulus cells. The data also demonstrated that ZIF-1, a glycoprotein isolated from human follicular fluid, was immunologically similar to glycodelin. In conclusion, we suggest that glycodelin is synthesized in the granulosa cells of ovarian follicles at late secondary follicle stage. It then may be released into the follicular fluid from where it is taken up and partially modified by the cumulus cells.

A compendium of gene expression in normal human tissues

This study creates a compendium of gene expression in normal human tissues suitable as a reference for defining basic organ systems biology. Using oligonucleotide microarrays, we analyze 59 samples representing 19 distinct tissue types. Of approximately 7,000 genes analyzed, 451 genes are expressed in all tissue types and designated as housekeeping genes. These genes display significant variation in expression levels among tissues and are sufficient for discerning tissue-specific expression signatures, indicative of fundamental differences in biochemical processes. In addition, subsets of tissue-selective genes are identified that define key biological processes characterizing each organ. This compendium highlights similarities and differences among organ systems and different individuals and also provides a publicly available resource (Human Gene Expression Index, the HuGE Index, http://www.hugeindex.org) for future studies of pathophysiology.

Myxoma of the gingiva: a case report and literature review

Soft tissue myxomas of the oral and para-oral tissue are extremely rare. Only two cases of myxoma of gingiva have been reported in the literature. The histogenesis of these lesions remains obscure. We report a case of gingival myxoma in a 37-year-old man. A firm ovoid soft tissue mass measuring 1.5 x 1.2 x 1 cm in size was noted at the mesio-lingual gingiva of a partially impacted right mandibular third molar. Radiographic examination revealed an impacted mandibular third molar with normal radiographic bony consistency of the mandible. Excisional biopsy was performed with no evidence of recurrence after 8 months. Histological examination showed stromal mass composed of myxoid-like fluid in fibrovascular stroma and scanty inflammatory cell infiltration, suggesting myxomas of the oral soft tissues and jaws. Immunohistochemical stains with S-100 protein, desmin and smooth muscle specific actin yielded negative results, and those with alcian blue, periodic-acid-Schiff, mucicarmine, vimentin and reticulin were positive. Tumor cells of mesenchymal origin without neurogenic or muscular derivations and myxoid matrix composed of acid mucopolysaccharides in this lesion further confirmed the diagnosis of myxoma. Periodontal ligament origin cannot be completely excluded due to tumor location and its association with an impacted molar. However, further study is necessary to clarify the origin and histogenesis of these lesions.