Lymphatic mapping and sentinel lymph node biopsy in the detection of early metastasis from sweat gland carcinoma.

BACKGROUND Several subtypes of sweat gland carcinoma have been found to demonstrate a propensity to metastasize systemically and to regional lymph nodes. The predictive value and benefit of sentinel lymph node (SLN) biopsy have been established in numerous other malignancies, but to the authors' knowledge there is little literature published to date regarding the use of SLN biopsy in patients with sweat gland carcinoma. In the current study, the authors demonstrated the utility of SLN biopsy in detecting subclinical metastases of sweat gland carcinoma, which may result in early treatment. METHODS The authors identified five patients with malignant eccrine tumors in whom SLN biopsy was performed at the study institution. Clinical and histopathologic data were reviewed. RESULTS The five study cases included two cases of aggressive digital papillary adenocarcinoma (both occurring on upper extremity digits), two cases of hidradenocarcinoma (occurring on the knee and foot, respectively), and an eccrine carcinoma (occurring on the scalp). In each biopsy-established case, there was no clinical evidence of metastatic disease, and a wide local excision or amputation was performed with concurrent SLN biopsy. Four of 18 SLNs in 3 of the 5 patients (60%) were found to be positive for metastatic carcinoma, as identified in hematoxylin and eosin stains and/or cytokeratin immunohistochemical stains. All three lymph node-positive patients subsequently underwent regional lymphadenectomy and were found to have no evidence of additional metastases. CONCLUSIONS The results of the current study demonstrate that SLN biopsy detects subclinical metastases from sweat gland carcinomas to regional lymph nodes. SLN mapping and biopsy at the time of resection can provide useful information with which to guide early treatment. Further studies are necessary to determine whether this procedure results in a survival benefit in patients with sweat gland carcinomas.