Institutional and comprehensive review of laryngeal leukoplakia.

OBJECTIVES: The nature and interpretation of vocal fold leukoplakia has been limited by small study sizes. The present study reviewed institutional data and the published literature to better characterize vocal fold leukoplakia. METHODS: At our institution, the histopathology, age, and malignant conversion rates of 136 patients (208 biopsies) with vocal fold leukoplakia from 1990 to 2005 were reviewed. RESULTS: No dysplasia (ND), mild and/or moderate dysplasia (MM), and severe dysplasia and/or squamous cell carcinoma in situ (SS) was identified in, respectively, 110 of 208 (53%), 38 of 208 (18%), and 31 of 208 (15%) biopsies. After 30 months (range, 1 to 134 months), malignant transformation was observed in 8 patients on subsequent biopsies. Additionally, a literature search was performed from 1960 to 2005 for the medical subject headings (MeSH) premalignant laryngeal lesions, laryngeal dysplasia, laryngeal leukoplakia, vocal cord dysplasia, and hyperkeratosis of the larynx. Fifteen reports were included for review. When these were combined with our institutional data, 1,173 of 2,188 biopsies (53.6%) revealed ND. Mild and/or moderate dysplasia and SS were present in 717 of 2,140 (33.5%) and 375 of 2,471 (15.2%) biopsies, respectively. Squamous cell carcinoma developed in 52 of 1,388 (3.7%), 83 of 824 (10.1%), and 56 of 310 (18.1%) patients whose initial biopsies demonstrated ND, MM, or SS. CONCLUSIONS: More than half of the reported leukoplakia lesions with biopsies showed ND. However, even lesions characterized as ND were associated with an increased risk of development of squamous cell carcinoma. Importantly, the risk of developing malignancy appears to correlate with the severity of dysplasia present on initial biopsy. Because clinical examination does not accurately predict the risk of malignancy, future studies, including genomic evaluation of this lesion, may be necessary to further characterize its biologic behavior.

Comparative effects of phthalate monoesters on gap junctional intercellular communication and peroxisome proliferation in rodent and primate hepatocytes.

Several phthalate esters, compounds used as plasticizers in a variety of commercial products, have been shown to induce hepatic tumors in rodents. In this study, the comparative effects of phthalate monoesters on inhibition of gap junctional intercellular communication and induction of peroxisomal beta-oxidation were assessed in primary cultured hepatocytes from rats, mice, hamsters, cynomolgus monkeys, and humans. A human liver cell line was also utilized. Eight monoesters examined included mono-2-ethylhexyl phthalate (MEHP), mono-n-octyl phthalate (MNOP), mono-isononyl phthalate (MINP, 3 types, -1, -2, and -3), mono-isoheptyl phthalate (MIHP), mono-isodecyl phthalate (MIDP), and mono-(heptyl, nonyl, undecyl) phthalate (M711P). Gap junctional intercellular communication was measured 4 and 24 h after treatment by lucifer yellow dye coupling. Gap junctional intercellular communication was inhibited in rat and mouse hepatocytes by all eight monoesters in a concentration-dependent manner. In most cases, gap junctional intercellular communication was significantly reduced at the lowest concentrations tested (50 pM). Inhibition of gap junctional intercellular communication in rodent cells was substantially reversed within 24 h of monoester removal. In contrast, cell-to-cell communication was not inhibited in hamster, cynomolgus, or human hepatocytes or in a human liver cell line at any concentration examined. In rat hepatocytes, peroxisomal beta-oxidation was elevated after treatment with MEHP, MINP, MIHP, and MIDP but not MNOP or M711P, and with all but MIHP in mouse hepatocytes. The eight phthalates produced no marked change on peroxisomal beta-oxidation in hepatocytes from other species. These data provide additional evidence that the toxicological effects of phthalate esters are species specific.