Clinical relevance of molecular staging for melanoma: comparison of RT-PCR and immunohistochemistry staining in sentinel lymph nodes of patients with melanoma

Ann Surg. 2000 Jun;231(6):795-803. doi: 10.1097/00000658-200006000-00003.


Objective: To determine the clinical significance of a molecular assay based on the reverse transcriptase polymerase chain reaction (RT-PCR) for the presence of micrometastatic melanoma cells in sentinel lymph nodes (SLNs).

Summary background data: Routine histologic examination of lymph nodes often underestimates the presence of micrometastatic disease. The authors have previously shown that an RT-PCR assay designed to detect melanocyte-specific expression of the tyrosinase gene could be used to define a population of patients at higher risk for both recurrence and death compared with routine hematoxylin and eosin (H&E) histology. In this study, the authors used the tyrosinase RT-PCR assay in a patient population examined by a more detailed histologic analysis, including S-100 immunohistochemistry.

Methods: Patients underwent lymphatic mapping and SLN biopsy. SLN specimens were bivalved, and half of each specimen was serially sectioned and examined by routine H&E histology and S-100 immunohistochemistry. The other half of each specimen was analyzed by a nested RT-PCR assay.

Results: Hematoxylin and eosin histology detected metastatic disease in 36 (16%) of the 233 patients tested. S-100 immunohistochemistry detected micrometastatic disease in another 16 patients, and 114 (63%) of 181 patients with histology-negative nodes had positive findings on RT-PCR. There were significant differences between PCR-positive and PCR-negative patient groups in Breslow thickness, Clark level, and the presence of ulceration of the primary tumor, factors that have been shown to correlate with recurrence and survival.

Conclusions: These results suggest that RT-PCR can increase the sensitivity of detection of metastatic melanoma cells in SLNs over the current standard methods, including H&E histology and S-100 immunohistochemistry. Further long-term follow-up is needed to detect actual differences in recurrence and overall survival.

MeSH terms

  • Adult
  • Aged
  • Female
  • Humans
  • Immunohistochemistry
  • Lymph Nodes / pathology*
  • Male
  • Melanoma / pathology*
  • Middle Aged
  • Neoplasm Staging / methods*
  • Prospective Studies
  • Reverse Transcriptase Polymerase Chain Reaction*
  • Skin Neoplasms / pathology*