Frozen section analysis of sentinel lymph nodes in melanoma patients.

BACKGROUND: The sentinel lymph node biopsy (SLNB) is a diagnostic or staging option in the treatment of patients with cutaneous malignant melanoma (CMM) and is investigated intensively. A positive SLNB has appeared to identify patients who might have benefited from a lymph node dissection (LND). Intraoperative frozen section analysis (FSA) of the sentinel lymph node (SLN) during surgery would allow SLNB and LND to be performed in the same procedure. In the current study, we tested the reliability of FSA on the sentinel lymph node in patients with CMM. METHODS: Before definitive treatment of their melanomas began, FSA was performed on the SLNBs of 58 patients, whose median age was 56 (22-81) years, and who were 55% male and 45% female. Serial sections (500 micrometer interval), stained with routine hematoxylin and eosin and immunohistochemistry (S-100 and HMB-45), obtained definitive histology of the sentinel lymph node. RESULTS: Detection of the sentinel lymph node was possible in 56 patients (97%). Sixty-one SLNBs were performed in these patients. FSA detected metastases in 5 of 108 SLN (5%) in 5 patients. This was upgraded after definitive histology to 13 SLN (12%) in 11 patients (20%). Sensitivity of the FSA was 38%. After a median follow-up of 35 (range: 24-54) months, the false-negative rate of the SLN was 4% (2 patients). CONCLUSION: The combination of the low sensitivity of FSA and a finding that only 12% of the SLNBs contained metastases does not justify routine use of FSA on the SLN of patients with CMM.

Iodine-131 Hippuran for the estimation of renal plasma flow: requirements for radiochemical purity.

For many years iodide-131 Hippuran has been used as a tracer to measure effective renal plasma flow (ERPF). Because of the low renal clearance of free 131I-iodide and the inability to count it separately from 131I-Hippuran, free 131I-iodide will lower the calculated 131I-Hippuran clearance, resulting in a lower estimated ER-PF. This study was performed to establish the maximum allowable radiochemical impurity of free 131I-iodide in 131I-Hippuran preparations for ERPF measurements in continuous clearance studies. A known amount of 123I-iodide was added to the (131I-iodide-free) 131I-Hippuran solution used for continuous infusion clearance studies in nine patients. 123I-iodide activity was used because it can be counted separately from 131I-Hippuran in the infusion solutions and plasma samples while it behaves exactly like 131I-iodide, so that the results obtained with 123I-iodide can be extrapolated to 131I-iodide. After performing the clearance studies, the ERPF was calculated firstly with 131I-Hippuran activity only (= true ERPF) and secondly including the free radioactive iodide activity (= false ERPF) in the clearance formula. As expected, if free 131I-iodide is present in the infusion solution, its concentration in plasma will be highest at the end of the clearance study. The 131I-iodide concentration in plasma relative to the 131I-Hippuran concentration will be higher in patients with high ERPF values.(ABSTRACT TRUNCATED AT 250 WORDS)