Does intensive histopathological workup by serial sectioning increase the detection of lymph node micrometastasis in patients with primary cutaneous melanoma?

Various histopathological techniques have been developed in order to improv e the detection of micrometastasis in the regional lymph nodes of patients with malignant melanoma, Our standard histopathological examination of lymp h nodes included haematoxylin and eosin (H & E) staining and immunohistoche mistry (IH) using antibodies to HMB-45 and S-100 proteins of three paraffin sections at one level. In addition, lymph nodes were examined by molecular biological methods using tyrosinase reverse transcription-polymerase chain reaction (RT-PCR). In this study, we investigated the use of step sections and IH in lymph nodes regarded as negative by standard histopathology but positive by tyrosinase RT-PCR, suggesting the presence of tumour cells. In a series of 76 consecutive patients with stage I and II cutaneous melanoma, a total of 156 regional lymph nodes were examined by H & E staining, IH an d tyrosinase RT-PCR. All lymph nodes were bisected along their long axis fo r separate evaluation. In 21 patients, at least one lymph node in the regio nal nodal basin reported as tumour-negative by standard histopathology was demonstrated to express tyrosinase (total number of nodes = 33). These 33 l ymph nodes were re-examined by H & E and IH at 10 additional levels of the paraffin block. Only one lymph node from one patient had occult melanoma ce lls in deeper levels detected exclusively by IH. Six out of 20 patients wit h positive findings exclusively on tyrosinase RT-PCR developed tumour recur rences during a median follow-up of 34 months. We therefore conclude that a dditional step sectioning with IH does not significantly increase the detec tion of tumour-positive lymph nodes. Patients with melanoma cells detected exclusively by RT-PCR, however, were shown to be at increased risk for tumo ur recurrence. (C) 2001 Lippincott Williams & Wilkins.