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L K Tan

Publications and source records attributed to L K Tan.

At least 37 records · Page 2Linked to original sources
PubMed2001

Complete branchial fistula. Case report and review of the literature.

Branchial anomalies, a result of aberrant embryonic development, are rarely seen in clinical practice. Lesions of the second branchial pouch commonly present as a neck lump or discharging sinus that may be complicated by infection. Clinical examination often reveals the lesion to be related to the junction of the upper two thirds and the lower one third of the sternocleidomastoid muscle. Branchial fistulas often present as a discharging sinus in the neck with the fistula tract extending upward within the deep neck tissue for a variable distance. A complete branchial fistula is one that has a defined internal opening in the tonsillar area and an external opening at the skin overlying the sternocleidomastoid muscle at the junction of the upper two thirds and the lower one third of the muscle. The incidence of such lesions is extremely rare. Surgical excision is the treatment of choice for branchial anomalies. We present the case of a patient who presented with a complete branchial fistula and discuss the clinical presentation and surgical management of such lesions, with a review of the relevant literature.

Adult↗
PubMed2000

In microdissected ductal carcinoma in situ, HER-2/neu amplification, but not p53 mutation, is associated with high nuclear grade and comedo histology.

BACKGROUND: HER-2/neu and p53 are two molecular markers that have been the focus of investigation in patients with invasive breast carcinoma. However, most of the published data have relied on immunohistochemical detection of the proteins as a surrogate marker of the underlying genetic alterations, a detection method that often gives variable results due to technical factors. In addition, there are limited data documenting HER-2/neu amplification and p53 mutations in the various histologic subtypes of ductal carcinoma in situ (DCIS). The authors evaluated a series of microdissected, pure DCIS lesions comprising a spectrum of morphologic subtypes (comedo, micropapillary, papillary, cribriform, and solid) and their corresponding normal breast tissue for genetic aberrations in HER-2/neu and p53. METHODS: HER-2/neu amplification was determined by differential polymerase chain reaction, and p53 mutations were identified by single-strand conformation polymorphism analysis. RESULTS: HER-2/neu amplification was identified in 12 of 30 DCIS samples (40%), and p53 mutations were identified in 6 of 30 DCIS samples (20%). The genetic alterations were not present in any of the normal breast tissue samples. HER-2/neu amplification occurred predominantly in the comedo subtype (69% vs. 18% of the noncomedo subtype; P = 0.008) and in lesions of high nuclear grade (63% vs. 14% of low grade; P = 0.01). There was no difference in the frequency of p53 mutations among the subtypes or between low grade and high grade lesions. No correlation between the presence of the two genetic alterations was observed. CONCLUSIONS: The presence of HER-2/neu amplification, but not p53 mutations, correlates with histologic subtype and nuclear grade. The relatively frequent occurrence of HER-2/neu amplification and p53 mutations in DCIS tissue and their absence in normal breast tissue suggest that these genetic aberrations are important early in breast duct carcinogenesis.

Breast Neoplasms↗
PubMed2000

Sentinel lymph node biopsy: is it indicated in patients with high-risk ductal carcinoma-in-situ and ductal carcinoma-in-situ with microinvasion?

BACKGROUND: Axillary lymph node status is the strongest prognostic indicator of survival for women with breast cancer. The purpose of this study was to determine the incidence of sentinel node metastases in patients with high-risk ductal carcinoma-in-situ (DCIS) and DCIS with microinvasion (DCISM). METHODS: From November 1997 to November 1999, all patients who underwent sentinel node biopsy for high-risk DCIS (n = 76) or DCISM (n = 31) were enrolled prospectively in our database. Patients with DCIS were considered high risk and were selected for sentinel lymph node biopsy if there was concern that an invasive component would be identified in the specimen obtained during the definitive surgery. Patients underwent intraoperative mapping that used both blue dye and radionuclide. Excised sentinel nodes were serially sectioned and were examined by hematoxylin and eosin and by immunohistochemistry. RESULTS: Of 76 patients with high-risk DCIS, 9 (12%) had positive sentinel nodes; 7 of 9 patients were positive for micrometastases only. Of 31 patients with DCISM, 3 (10%) had positive sentinel nodes. 2 of 3 were positive for micrometastases only. Six of nine patients with DCIS and three of three with DCISM and positive sentinel nodes had completion axillary dissection; one patient with DCIS had an additional positive node detected by conventional histological analysis. CONCLUSIONS: This study documents a high incidence of lymph node micrometastases as detected by sentinel node biopsy in patients with high-risk DCIS and DCISM. Although the biological significance of breast cancer micrometastases remains unclear at this time, these findings suggest that sentinel node biopsy should be considered in patients with high-risk DCIS and DCISM.

Adult↗
PubMed2000

Is routine intraoperative frozen-section examination of sentinel lymph nodes in breast cancer worthwhile?

BACKGROUND: Routine intraoperative frozen section (FS) of sentinel lymph nodes (SLN) can detect metastatic disease, allowing immediate axillary dissection and avoiding the need for reoperation. Routine FS is also costly, increases operative time, and is subject to false-negative results. We examined the benefit of routine intraoperative FS among the first 1000 patients at Memorial Sloan Kettering Cancer Center who had SLN biopsy for breast cancer. METHODS: We performed SLN biopsy with intraoperative FS in 890 consecutive breast cancer patients, none of whom had a back-up axillary dissection planned in advance. Serial sections and immunohistochemical staining for cytokeratins were performed on all SLN that proved negative on FS. The sensitivity of FS was determined as a function of (1) tumor size and (2) volume of metastatic disease in the SLN, and the benefit of FS was defined as the avoidance of a reoperative axillary dissection. RESULTS: The sensitivity of FS ranged from 40% for patients with Tla to 76% for patients with T2 cancers. The volume of SLN metastasis was highly correlated with tumor size, and FS was far more effective in detecting macrometastatic disease (sensitivity 92%) than micrometastases (sensitivity 17%). The benefit of FS in avoiding reoperative axillary dissection ranged from 4% for Tla (6 of 143) to 38% for T2 (45 of 119) cancers. CONCLUSIONS: In breast cancer patients having SLN biopsy, the failure of routine intraoperative FS is largely the failure to detect micrometastatic disease. The benefit of routine intraoperative FS increases with tumor size. Routine FS may not be indicated in patients with the smallest invasive cancers.

Adult↗
PubMed2000

Complications of foreign bodies in the esophagus.

Major complications of foreign bodies in the esophagus carry significant morbidity and mortality risks. A retrospective case control study was performed to assess the factors associated with major complications. In total, 273 patients seen within a 7-year period were divided into 2 groups; 253 had no or minor complications, and 20 had major complications. Age, sex, duration of the foreign body, total white cell count (TWC), and nature and site of the foreign body were analyzed in the 2 groups. The major complication rate was 7.3%. Duration of the foreign body and TWC were the only statistically significant factors associated with major complications. Six patients required open neck exploration, 1 had an open thoracotomy, and 13 were treated by endoscopic removal. There were 2 deaths. Given the significant morbidity and mortality risks, we conclude that patients with a prolonged history of a foreign body in the esophagus and a raised TWC should be treated urgently.

Adult↗
PubMed2000

Cloning and expression of immunoreactive antigens from Mycobacterium tuberculosis.

Four immunoreactive proteins, B.4, B.6, B.10, and B.M, with molecular weights ranging from 16,000 to 58,000, were observed from immunoblots of Mycobacterium tuberculosis total lysates screened with sera from individuals with active tuberculosis. These proteins were identified from microsequence analyses, and genes of proteins with the highest homology were PCR amplified and cloned into the pQE30 vector for expression studies. In addition, a 37.5-kDa protein, designated C17, was identified from a phage expression library of M. tuberculosis genomic DNA. Preliminary immunoblot assays indicated that these five resultant recombinant proteins could detect antibodies in individuals with active pulmonary and extrapulmonary tuberculosis. The overall ranges of sensitivities, specificities, positive predictive values, and negative predictive values for the recombinant antigens were 20 to 58, 88 to 100, 69 to 100, and 56 to 71%, respectively. The B.6 antigen showed preferential reactivity to antibodies in pulmonary compared to nonpulmonary tuberculosis serum specimens. All of these recombinant antigens demonstrated potential for serodiagnosis of tuberculosis.

Antigens, Bacterial↗
PubMed2000

Evaluation of pectoralis major muscle in patients with posterior breast tumors on breast MR images: early experience.

PURPOSE: To evaluate the ability to use breast magnetic resonance (MR) imaging to assess disease extent in patients with posterior breast masses who are suspected to have tumor invasion into underlying muscle. MATERIALS AND METHODS: Nineteen patients with posterior breast masses underwent three-dimensional, gradient-echo, 1.5-T MR imaging before and after the administration of gadopentetate dimeglumine. Thirteen had deep palpable masses that were clinically determined to be fixed to the underlying chest wall. Twelve had mammographic findings that caused muscle involvement to be suspected, and seven had normal mammograms. All patients underwent surgery. MR images were reviewed and were correlated with histologic findings. RESULTS: Enhancing masses were identified on MR images in all 19 patients. Five (26%) of the 19 patients had masses that abutted the muscles, with obliteration of the fat plane and muscle enhancement. All five had muscle involvement at surgery. In the remaining 14 (74%) patients, no enhancement of muscle was seen; none of these had invasion of the muscle at surgery. CONCLUSION: Extension of adjacent tumor into underlying musculature was indicated by abnormal enhancement within these structures. Violation of the fat plane between tumor and muscle, without other findings, did not indicate tumor involvement of these deep structures.

Adult↗
PubMed2000

Immunoglobulin D multiple myeloma in our hospital--a rare occurrence.

Immunoglobulin (Ig) D multiple myeloma is a rare presentation, usually with an aggressive course and a poorer prognosis. It accounts for about 1-2% of newly diagnosed mulitple myeloma patients. Due to its rarity, reports on Ig D multiple myeloma are limited in the literature. We therefore present 4 cases of Ig D multiple myeloma in our hospital over a period of 8 years between 1990 to 1998. The average age of presentation of our patients was 44 years old with a female preponderance. Common presenting symptoms were appetite and weight loss and bone pain. Two patients presented with neurological symptoms and 2 with renal impairment. Three patients had an associated lambda paraproteinaemia and the fourth had a kappa paraproteinaemia. A common finding in Ig D myeloma is a small or no spike seen on serum electrophoresis together with heavy Bence Jones proteinuria. A review of the literature on Ig D myeloma is also presented.

Adult↗
PubMed1999

Six-year follow-up of patients with microinvasive, T1a, and T1b breast carcinoma.

BACKGROUND: Management of patients with breast cancers < or = 1 cm remains controversial. Reports of infrequent nodal metastases in tumors < or = 5 mm has led to suggestions that axillary dissection should be selective, and that tumor characteristics should guide adjuvant therapy. METHODS: A retrospective review of 290 patients with breast cancer 1 cm in size or smaller from 1989 to 1991 was done. Distant disease-free survival (DDFS) was the primary outcome measure. RESULTS: There were 95 T1a (< or = 5 mm) and 196 T1b (6-10 mm) cancers. Nodal metastases were found in 8 T1a and 26 T1b tumors. Larger size, poorer differentiation, and lymphovascular invasion (LVI) were associated with more nodal metastases, but none of these trends reached statistical significance. The 6-year DDFS was 93% for node-negative and 87% for node-positive patients (P = .02). Overall, breast cancers with poorer differentiation and LVI trended toward a poorer outcome. For patients with node-negative tumors, LVI was associated with a poorer outcome (P = .03). The size of the primary tumor was not predictive of outcome. There were no nodal metastases or recurrences in the 18 patients with microinvasive breast cancer. CONCLUSIONS: Lymph node status is the major determinant of outcome in breast cancers 1 cm in size or smaller. Accurate axillary assessment remains crucial in management of small breast cancer.

Adult↗
PubMed1999

Epistaxis.

Epistaxis is a common clinical problem. The widespread availability of endoscopic equipment is shifting management philosophy toward targeting the bleeding point. This shift may have a significant impact on decreasing length of stay and blood transfusion rates. Advances in interventional radiology have also reduced the risk of embolization. Patient education, especially teaching first-aid measures to patients at high risk for nosebleeds, also encourages more effective use of health care resources.

Blood Transfusion↗
PubMed1999

Cytotoxicity and DNA interaction of the enantiomers of 6-amino-3-(chloromethyl)-1-[(5,6,7-trimethoxyindol-2-yl)carbonyl]indo- line (amino-seco-CI-TMI).

The enantiomers of the previously reported racemic 6-amino-3-(chloromethyl)-1-[(5,6,7-trimethoxyindol-2-yl)carbonyl] indoline (amino-seco-CI-TMI) were prepared via resolution of a precursor by chiral HPLC. The only detectable product isolated from reaction of the racemic compound with calf thymus DNA, followed by thermal cleavage, was shown by mass spectrometry and two-dimensional NMR spectroscopy to be the adenine N3 adduct. Polyacrylamide gel electrophoresis assays with the racemate and with each enantiomer also showed adenine to be the only site of alkylation. While the racemic amino compound exhibited sequence selectivity identical to that of the previously characterized phenol analogue, the enantiomers exhibited distinctly different sequence selectivities, allowing the (+) enantiomer to be assigned the "natural" S configuration. The (+)-(S) enantiomer is 3-fold more cytotoxic than the (-)-(R) enantiomer (IC(50) values of 240 and 700 nM, respectively, in AA8 cells, after exposure for 4 h).

Alkylation↗
PubMed1999

Lymphangiomyomatosis: radiological and measured lung function deterioration after contrast-enhanced computed tomography.

Pulmonary lymphangiomyomatosis (LAM) is a rare disease of unknown aetiology which occurs exclusively in women, usually of reproductive age. The findings on CT and high-resolution CT (HRCT) are well described and characteristic, and in a young woman they are virtually pathognomonic. A case of symptomatic, radiological and measured lung function deterioration following contrast-enhanced CT in a patient with LAM are reported here. These observations, to the authors' knowledge, have never been reported before. The authors attempt to explain these observations based on the known pathology of LAM.

Adolescent↗
PubMed1999

Two dosing regimens for preinduction cervical priming with intravaginal dinoprostone pessary: a randomised clinical trial.

OBJECTIVE: To compare the efficacy within 24 hours of a three-times-a-day intensive dosing regimen with a standard once daily dosing regimen using dinoprostone vaginal pessary in preinduction cervical priming. DESIGN: Randomised controlled trial. SETTING: Department of Obstetrics and Gynaecology, Singapore General Hospital. PARTICIPANTS: One hundred singleton term primigravidae with cephalic presentation with unfavourable cervical scores (Bishop score < or = 5) requiring induction of labour. METHODS: Eligible women were randomly assigned the standard regimen (3000 microg dinoprostone [Prostin, Upjohn, Crawley, UK] once daily) or an intensive regimen (3000 microg dinoprostone given sequentially three times daily four hours apart) for cervical priming until successful priming (Bishop score of > or = 6) or the onset of active labour occurred. MAIN OUTCOME MEASURES: Number of women whose cervices were ripened successfully or who entered active labour within 24 hours of starting cervical priming, priming to induction interval, and priming to delivery interval. RESULTS: Forty-nine women were assigned to the standard regimen and 51 to the intensive regimen. The median number (range) of dinoprostone pessaries used was two (one to seven) in the standard regimen and three (one to nine) in the intensive regimen. Forty-two women (82.4%) who underwent the intensive regimen achieved successful cervical ripening or active labour within 24 hours, compared with 21 assigned to standard regimen (OR 6.2, 95% CI 2.3-17.4). This difference was statistically significant. The median intervals from priming to induction, and from priming to delivery, were also statistically significantly shorter in women treated with the intensive regimen. Thirty-five women (68.63%) assigned the intensive regimen experienced pain, compared with 21 (42.86%) in the standard regimen (OR 2.92, 95% CI 1.19-7.21), with two and one women in the respective regimens requiring opiate analgesics. Five women with oligohydramnios had transient cardiotocographic abnormalities during priming with the intensive regimen, none of which required immediate intervention, and the babies were born in good condition. There were no cases of uterine hypertonus and the outcomes of labour were similar for women from both regimens. CONCLUSIONS: Preinduction cervical priming with the intensive dosing regimen improves the chances of successful ripening within 24 hours for primigravidae with unfavourable cervical scores at full term singleton pregnancies, and shortens the interval from priming to induction, and priming to delivery. This regimen may be more cost effective by shortening the period of hospital stay. The overall incidence of adverse reactions to the mother and fetus during priming was low. However, close fetal surveillance must be maintained, particularly in pregnancies complicated with oligohydramnios.

Administration, Intravaginal↗
PubMed1999

Epidermal growth factor, estrogen, and progesterone receptor expression in primary sweat gland carcinomas and primary and metastatic mammary carcinomas.

The distinction between primary sweat gland carcinomas and metastatic breast carcinoma to the skin is sometimes difficult. In an effort to improve this discrimination, we compared the immunohistochemical staining pattern of 42 primary sweat gland carcinomas (SGCs) with 30 metastases from breast carcinoma (BC) to the skin, 125 primary BCs, and 30 noncutaneous metastases from BCs. The antibodies used were against the receptors for epidermal growth factor (EGF-R), estrogen receptor (ER), and progesterone receptor (PR). The frequencies of positive staining were as follows for EGF-R: 34 (81%) of 42 SGCs, 5 (17%) of 30 BCs metastatic to skin, 28 (22%) of 125 primary BCs, and 6 (20%) of 30 noncutaneous BC metastases. For ER, the frequencies were 9 (21%) of 42 SGCs and 10 (33%) of 30 BCs metastatic to skin. The frequencies for PR were 8 (19%) of 42 SGCs and 8 (27%) of 30 BCs metastatic to skin. These results suggest that expression of EGF-R may be diagnostically helpful, because it is strongly associated with SGCs when compared with metastatic BCs (P < .0001). This association is also present when ductal eccrine and apocrine types of SGC, which are the histologic subtypes of SGC most difficult to distinguish from metastatic BC, are separately analyzed (P < .001). The frequencies of expression of ER and PR in SGCs and BCs metastatic to skin were not significantly different.

Adult↗