Immunohistochemical study of 40 cases of longitudinal melanonychia

The etiology of longitudinal melanonychia (LM) is difficult to establish by clinical and dermoscopic examinations alone. Microscopic examination of the nail matrix remains crucial. Two groups of LM may be identified: melanocytic activation (melanic pigmentation of the matrix epithelium without any increase in the density of melanocytes) and melanocytic proliferation (lentigo, nevus, or melanoma). The histological examination is challenging, and immunohistochemical investigations can be helpful. The objective of this study was to analyze the immunohistochemical findings with routinely used markers in melanocytic tumors-S-100 protein, HMB-45, and Melan-A-in LM. A series of 40 cases were analyzed: 10 activations, 4 lentigines, 7 nevi, 12 in situ melanomas, and 7 invasive melanomas. The sensitivity of S-100 protein is weak in benign and malignant intraepithelial melanocytes of the nail matrix, and if this marker is performed alone, it may be wrongly reassuring. However, the use of S-100 protein is essential to differentiate invasive melanoma, lacking an intraepithelial component, and particularly desmoplastic melanoma, from epithelial and mesenchymal tumors. HMB-45 and Melan-A are more sensitive than S-100 protein for the evaluation of intraepithelial melanocytic proliferation of the nail apparatus, with HMB-45 being the most intense marker. In the dermal component, HMB-45 and Melan-A were less sensitive than S-100 protein. In conclusion, we recommend that the panel of antibodies used for histological evaluation of LM should include HMB-45 and/or Melan-A and S-100 protein only if an invasive melanoma is suspected.     

Effects of model inducers on thyroxine UDP-glucuronosyl-transferase activity in vitro in rat and mouse hepatocyte cultures.

Thyroxine (T₄)-UDP-glucuronosyltransferase (UGT) activity was measured directly in cultured male Sprague–Dawley rat and OF-1 mouse hepatocyte monolayers. The activity of T₄-UGT (pmol/min/g liver) in vitro in hepatocyte cultures was, after 24 hr in culture, equivalent to that previously measured in vivo in rat and mouse liver microsomes (Viollon-Abadie et al., 1999). A progressive decline in T₄-UGT activity occurred over time in both rat and mouse hepatocyte cultures. Treatment of cultures with various model inducers such as phenobarbital (PB), β-naphthoflavone (NF) and clofibric acid (CLO) induced a strong increase in T₄-UGT activity in rat hepatocyte monolayers. In addition, and as expected from available in vivo data, treatment of rat hepatocyte cultures with NF also increased p-nitrophenol (PNP)-UGT activity and treatment with PB or CLO increased bilirubin (Bili)-UGT activity. In contrast, T₄-UGT activity in mouse hepatocyte monolayers was not affected by the treatments, neither were PNP- and Bili- UGT activities. These in vitro data confirm our previous in vivo observations that these inducers increase rat but not mouse liver T₄-UGT activities (Viollon-Abadie et al., 1999). The present study thus demonstrates that hepatocyte monolayers are appropriated for the evaluation and inter-species comparison of the effects of xenobiotics on T₄-UGT activities.     

Demyelination occurring during anti-tumor necrosis factor alpha therapy for inflammatory arthritides.

OBJECTIVE: To review the occurrence of neurologic events suggestive of demyelination during anti-tumor necrosis factor alpha (anti-TNFalpha) therapy for inflammatory arthritides. METHODS: The Adverse Events Reporting System of the Food and Drug Administration (FDA) was queried following a report of a patient with refractory rheumatoid arthritis who developed confusion and difficulty with walking after receiving etanercept for 4 months. RESULTS: Nineteen patients with similar neurologic events were identified from the FDA database, 17 following etanercept administration and 2 following infliximab administration for inflammatory arthritis. All neurologic events were temporally related to anti-TNFalpha therapy, with partial or complete resolution on discontinuation. One patient exhibited a positive rechallenge phenomenon. CONCLUSION: Further surveillance and studies are required to better define risk factors for and frequency of adverse events and their relationship to anti-TNFalpha therapies. Until more long-term safety data are available, consideration should be given to avoiding anti-TNFalpha therapy in patients with preexisting multiple sclerosis and to discontinuing anti-TNFalpha therapy immediately when new neurologic signs and symptoms occur, pending an appropriate evaluation.