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Biomedical subjects

L K Tan

Publications and source records attributed to L K Tan.

115 records · Page 7Linked to original sources
PubMedDate not supplied

Incidence of axillary lymph node metastases in T1a and T1b breast carcinoma.

BACKGROUND: We investigated the incidence of axillary lymph node metastases in patients with T1a (< or = 0.5 cm) and T1b (> 0.5 cm and < or = 1.0 cm) breast cancers. METHODS: The charts of 2000 patients who underwent axillary lymph node dissection for breast cancer at our institution from 1989 to 1991 were reviewed. Of these, 81 patients had T1a and 166 had T1b primary breast cancers. RESULTS: Among the 247 patients with T1a and T1b breast cancers, nodal metastases were present in 30 (12.1%), with a 7.4% positivity rate for patients with T1a and 14.5% positivity rate for T1b tumors. Of the 212 patients who had > or = 10 nodes dissected, 29 (13.7%) had positive nodes. Of those, 6 of 60 (10.0%) patients with T1a and 23 of 152 (15.1%) with T1b tumors had positive nodes. The presence of lymphovascular invasion (LVI) predicted a significantly higher nodal positivity rate (27.8% vs. 10.9%, p = 0.05). CONCLUSIONS: Of patients with adequately evaluated axillae, 10% with T1a and 15% with T1b cancers were found to have nodal metastases. Although LVI was significantly associated with a higher risk of lymph node metastases, we could not characterize any subgroup at acceptably low risk of nodal positivity. Until a more useful prognostic indicator is discovered, axillary dissection should continue to be part of the mainstay of management for small breast cancers.

Axilla↗
PubMedDate not supplied

Absence of p16 gene (CDKN2) deletions in microdissected primary breast carcinoma specimens.

BACKGROUND: The p16 gene (CDKN2), a tumor suppressor gene located on chromosome 9p21, has been demonstrated to be mutated or deleted with high frequency in a variety of tumor cell lines, including breast. While previous studies have not demonstrated CDKN2 mutations in primary breast carcinomas, it is possible that gene deletion in neoplastic DNA was marked by the presence of contaminating normal stromal DNA in breast carcinoma specimens. METHODS: We investigated the incidence of homozygous deletion of CDKN2 by analyzing 20 microdissected pure populations of primary breast carcinoma cells. Using polymerase chain reaction (PCR) techniques, the entire coding region and intervening introns of CDKN2 were amplified. The PCR products were resolved by agarose gel electrophoresis and single-strand conformation polymorphism (SSCP) analysis. RESULTS: We detected no deletions or mutations of the p16 gene. CONCLUSIONS: CDKN2 is not deleted with high frequency in primary breast carcinomas, and the p16 gene does not play a role in breast carcinogenesis via this mechanism.

Breast Neoplasms↗
PubMedDate not supplied

Epidermoid cyst of the liver complicated by microscopic squamous cell carcinoma: CT, ultrasound, and pathology.

Though cystic hepatic lesions may have features that help characterize them by noninvasive imaging modalities, these findings are often nonspecific and may be unable to establish the presence of malignancy. This is illustrated here by describing an epidermoid cyst of the liver containing microscopic foci of squamous cell carcinoma. The importance of totally resecting an epidermoid cyst of the liver is emphasized.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Fine needle aspiration biopsy of hepatocellular carcinoma. Diagnostic dilemma at the ends of the spectrum.

A diagnostic dilemma exists at the extreme ends of the spectrum in the cytodiagnosis of hepatocellular carcinoma (HCC). The cytologic features of fine needle aspiration biopsies from 30 well- and 16 poorly differentiated HCC were reviewed and the adjunctive role of serum alpha-fetoprotein (AFP), hepatitis B virus (HBV) markers and radiologic findings evaluated. Some subtle features noted in very well differentiated HCC include small tumor cell size with increased nuclear/cytoplasmic ratio, monotony of atypia, hepatocytic tumor giant cells and narrow trabeculae with tendency for cell dissociation. Useful features in poorly differentiated HCC include cell dehiscence, large cells with ovoid nuclei and thickened nuclear membranes, and one or more increasingly prominent nucleoli, with some assuming a reniform configuration. The serum AFP levels are not always elevated. Positive HBV markers, cirrhosis and compatible imaging findings are suggestive but not diagnostic. The general inclination, however, is still toward a diagnosis of HCC if the aspirate is from a focal lesion or lesions in a hepatitis B surface antigen-positive, cirrhotic liver. Cell block sections provide histologic confirmation.

Adult↗
PubMedDate not supplied

Biliary cystadenocarcinoma arising in a cystadenoma. Report of a case diagnosed by fine needle aspiration cytology.

Hepatic cyst fluid cytology tends to yield disappointing results. We report a case of a 56-year-old woman with a biliary cystadenocarcinoma diagnosed by fine needle aspiration cytology. Computed tomography scans had shown a solitary, unilocular hepatic cyst over a five-year period. There was a recent increase in the size and development of a mural echogenic focus. Cytologic examination revealed clusters of malignant glandular cells in a background of cellular debris and mucinophages. The resected specimen confirmed the presence of an adenocarcinoma arising from malignant transformation of a preexisting cystadenoma.

Adenoma, Bile Duct↗
PubMedDate not supplied

The effect of a synthetic analogue of prostaglandin E2 on wound healing in rats.

This was a prospective, randomized, double-blind experimental study to assess the effect of a long-acting prostaglandin (PG) analogue on wound healing in rats. Eight-cm long, dorsal midline skin incisions were made on rats (n = 44) and immediately resutured. The treatment group (n = 22) received daily intraperitoneal injections of 16,16-dimethyl prostaglandin E2-methyl ester (di-MPGE2) for 7 days, whereas the controls (n = 22) received normal saline. The rats were sacrificed in groups of 11 at 7 and 14 days, respectively. The wounds were excised and analyzed. Histology showed that there was increased fibrosis (p < 0.03) and a decreased number of macrophages (p < 0.02) in the PG group at 7 days. Tensile strength and hydroxyproline content also increased but did not attain significant levels. The differences between the PG and control groups at 14 days similarly did not attain statistical significance. The results suggest that in wound healing, the administration of di-MPGE2 may be beneficial during the early stages of inflammation, rather than during the later stages of remodelling.

16,16-Dimethylprostaglandin E2↗