1. ¹Department of Pathology, Center for Medical Education and Clinical Investigation, Buenos Aires, Argentina
2. ²Division of Surgical Oncology, Hospital de Clínicas 'José de San Martín', University of Buenos Aires School of Medicine, Buenos Aires, Argentina
3. ³Department of Pathology, Hospital de Clínicas 'José de San Martín', University of Buenos Aires School of Medicine, Buenos Aires, Argentina

Correspondence: Dr VC Denninghoff, PhD, Department of Pathology, Center for Medical Education and Clinical Investigation, Arcos 1853 1oB, Buenos Aires C1428AFA, Argentina. E-mail: vdenninghoff@cemic.edu.ar

Received 26 July 2007; Revised 2 December 2007; Accepted 3 December 2007; Published online 25 January 2008.

Abstract

Lymph node mapping and sentinel lymph node biopsy are currently used to stage patients with cutaneous malignant melanoma. Immunohistochemical stains contribute to the detection of micrometastases; however, molecular biology techniques are associated with better diagnostic sensitivity. Sixty sentinel lymph nodes were included in this study. The primary lesions were malignant melanoma stage I or II, with a follow-up of longer than 2 years. Sentinel lymph nodes were studied with hematoxylin–eosin, immunohistochemistry for S-100 and HMB-45, and molecular biology techniques (reverse transcription (RT)-PCR) for the detection of tyrosinase messenger RNA. In 15 of 60 cases (25%), tyrosinase was detected by RT-PCR; three of these cases were also positive by immunohistochemistry. The population was divided into three groups: (i) hematoxylin–eosin-/immunohistochemistry+/molecular biology techniques+ (3 cases); (ii) hematoxylin–eosin-/immunohistochemistry-/molecular biology techniques+ (12 cases); (iii) hematoxylin–eosin-/immunohistochemistry-/molecular biology techniques- (45 cases). Correlation of the groups with overall survival showed the following: (i) 2 of 3 patients died (67%); (ii) 5 of 12 died (42%), and (iii) all 45 patients are alive, with no lymphadenectomy and a median follow-up of 84 months. The inclusion of molecular biology techniques appears to be of great value for the detection of sentinel lymph node micrometastases in patients with cutaneous malignant melanoma. In our series, those patients who showed negativity with all the three methods had a null recurrence rate. Therefore, this triple negativity could be a positive prognostic factor for overall survival. Our findings suggest the possibility of molecular oncological staging, which would allow the selection of patients with submicroscopic metastases for a complete treatment.