Sentinel lymph node biopsy in thin melanoma patients.

BACKGROUND

We sought to determine the incidence of positive sentinel lymph nodes in thin melanoma (<or=1.0 mm) patients and if subgroups could be identified with a higher risk of occult nodal disease.

METHODS

Patients with <or=1.0 mm lesions treated between 1997 and 2003 were reviewed. Sentinel nodes underwent microscopic analysis including step sectioning and immunohistochemical examination. Some nodes underwent reverse transcriptase-polymerase chain reaction (RT-PCR) evaluation for melanoma markers.

RESULTS

Sixty-four of 107 thin melanoma patients underwent sentinel node biopsy (SNB). Mapped patients were more likely to have Clark >or= III and thicker lesions (mean 0.77 mm vs. 0.47 mm), but were not different in regards to age, sex, or lesion location. Eight percent and 58% of sentinel nodes were positive by routine histology and RT-PCR, respectively. Among mapped patients, younger age was the only significant prognostic factor for node positivity. With a median follow-up of 18 months among all patients, one regional recurrence (at 2 years) has been identified.

CONCLUSIONS

Given the low morbidity of sentinel lymph node biopsy, this procedure should be discussed with selected thin melanoma patients to detect microscopic disease, however PCR positivity by our methods is too commonly seen to be clinically significant in thin melanoma patients and requires additional study.