Lymphatic mapping and sentinel lymph node biopsy for malignant melanoma in Japanese.

Background: Clinical records of 24 Japanese patients suffering from a primary malignant skin tumor were summarized, and the efficacy of lymphatic mapping (LM) and sentinel lymph node biopsy (SLNB) in cases with possible lymphatic metastasis was investigated, and compared with previous reports.

Methods: There were 17 cases of malignant melanoma (MM), 4 of squamous cell carcinoma (SCC), 2 of extramammary Paget's disease, and 1 of eccrine porocarcinoma. LM and SLNB were performed as additional treatment during extended surgery.

Results: Blue-stained lymph ducts and nodes were observed in 21 of 24 cases (87.5% identification rate). In these 21 cases, 3 sentinel lymph nodes (SLNs) were identified in 1 patient (4.8%), 2 SLNs in 5 patients (23.8%), and one SLN in 15 patients (71.4%). In MM, distant metastasis was seen in 3 of 10 cases (30%) with negative SLN. In these 3 cases, Breslow's thickness of the tumor ranged from 2.0 to 3.9 mm (average 2.6 mm). Except for MM, no distant metastases were observed in 7 cases with negative SLN.

Conclusions: The incidence of MM in Japanese is about 0.001%, and the accumulation of reliable data is slow. Although MM is rare, SCC is more common. Therefore we investigated the clinical data of non-MM patients at risk of metastasis. SLN biopsy in non-MM patients was shown to be linked with their prognosis. In conclusion, the SLN biopsy technique is useful in the early stages of MM, and for non-MM patients at risk of lymphatic metastasis.