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Helene Nortvig Abrahamsen

Publications and source records attributed to Helene Nortvig Abrahamsen.

4 recordsLinked to original sources
PubMed2005

Pathologic assessment of melanoma sentinel nodes: a role for molecular analysis using quantitative real-time reverse transcription-PCR for MART-1 and tyrosinase messenger RNA.

PURPOSE: Molecular analysis of melanoma sentinel nodes (SN) is sensitive, but poorly specific because metastases cannot be distinguished from benign nevus inclusions (BNI). We investigated whether quantitative reverse transcription-PCR (RT-PCR) detection of MART-1 and tyrosinase mRNAs could improve this specificity and contribute to SN assessment. EXPERIMENTAL DESIGN: Two hundred twenty SNs from 95 melanoma patients analyzed by extensive immunohistopathology and real-time quantitative RT-PCR. RESULTS: Using histopathology, SNs and patients were allotted to three diagnostic groups: (a) metastasis positive, (b) BNI positive, and (c) melanocyte-free. Median MART-1 and tyrosinase mRNA levels in SNs were significantly different in patients with metastasis compared with patients with BNIs (P < 0.05) and patients without melanocytic lesions (P < 0.001). However, a "gray-zone" was observed where distinction, based on mRNA levels, could not be made between the three groups. For both genes, the highest mRNA level recorded in each RT-PCR-positive patient was positively correlated with Breslow's tumor thickness. For SNs with metastases, tumor burden was significantly correlated to the mRNA level. Using the presence of a MART-1 RT-PCR signal to detect patients with metastases, a sensitivity of 100% and a negative predictive value of 100% were achieved when extensive immunohistology was used as reference. CONCLUSIONS: Quantitative RT-PCR MART-1 and tyrosinase mRNA analysis cannot be used alone for SN diagnosis because of its poor specificity for melanoma metastasis. However, in approximately one third of cases without RT-PCR evidence of MART-1 expression, extensive histopathologic SN investigation is not necessary, thus substantially reducing the cost of SN analysis. The level of melanocyte-associated mRNA is associated with both tumor thickness and tumor burden as measured histopathologically, suggesting that this may be of prognostic value.

Adult↗
PubMed2004

Sentinel lymph nodes in malignant melanoma: extended histopathologic evaluation improves diagnostic precision.

BACKGROUND: The optimal technique for sentinel lymph node (SN) assessment in patients with melanoma is controversial. Molecular analysis (reverse transcriptase-polymerase chain reaction) detects significantly greater numbers of SNs with suspected micrometastases (up to 71%) than does routine histopathology (approximately 20%). The authors sought to identify possible reasons for this discrepancy and to determine whether using an extended histopathologic protocol could improve diagnostic precision. METHODS: Two hundred thirty-one SNs from 100 consecutive patients with cutaneous melanomas that measured 1-4 mm in thickness were bisected, and half of the lymph node was examined according to an extensive histopathologic protocol involving serial sectioning and immunohistochemical analysis of 3 melanocyte-associated markers (S-100, HMB-45, and Melan-A). RESULTS: Lymph node melanocytic lesions were frequent, with micrometastases and benign nevus inclusions (BNI) found in SNs in 28% and 28% of patients, respectively (4 SNs contained both). Melan-A was the most sensitive immunohistochemical marker and was positive in all BNI-positive SNs and 97% of micrometastasis-positive SNs. Although HMB-45 showed differential labeling in micrometastases compared with BNI (82% vs. 16%), immunohistochemistry could not distinguish between those lesions. Micrometastases were already identified on the first central level in 49% of positive SNs, whereas only 23% of SNs with BNI were diagnosed on the first level. CONCLUSIONS: Extensive serial sectioning with immunohistochemical analysis substantially increased the histopathologic detection of micrometastases and BNI in melanoma SNs to a level approaching the level reported for molecular techniques. The large number of BNIs represents an important potential source of imprecision (false positivity) in SN assays based on nonmorphologic methods.

Adult↗
PubMed2003

Towards quantitative mRNA analysis in paraffin-embedded tissues using real-time reverse transcriptase-polymerase chain reaction: a methodological study on lymph nodes from melanoma patients.

Improved extraction techniques combined with sensitive real-time reverse transcriptase-polymerase chain reaction may allow detection of mRNA in formalin-fixed, paraffin-embedded (FFPE) materials, but the factors affecting mRNA quantification in clinical material using these methods have not been systematically analyzed. We designed analyses using real-time reverse transcriptase-polymerase chain reaction for quantification of MART-1, beta-actin, and beta(2)-microglobulin mRNAs. The analytical intra- and interassay imprecision (coefficient of variation) was in the range 10 to 20% for all three genes studied. Using these protocols, we studied the influence of tissue autolysis and length of formalin-fixation on mRNA detection in metastatic melanoma. Delay in freezing reduced detectable mRNA, although this was less than predicted and mostly occurred early in autolysis. MART-1, beta-actin, and beta(2)-microglobulin mRNAs were consistently detected in FFPE metastatic melanoma even after fixation for up to 3 weeks, although the total mRNA detected was markedly reduced in fixed compared with fresh tissues (up to 99%). Quantification of MART-1 was, however, possible if this was expressed relative to a housekeeping gene. The polymerase chain reaction product from FFPE tissues could be increased up to 100-fold amplifying short (<136 bp) compared with long amplicons. Variations in time before tissue processing and in fixation length seem to be less important sources of imprecision than previously assumed. Our findings suggest that quantitative analysis of mRNA in archive and routine diagnostic tissues may be possible.

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