99mTc-human serum albumin: an effective radiotracer for identifying sentinel lymph nodes in melanoma.

UNLABELLED: Sentinel lymph node (SLN) biopsy has emerged as a novel approach for identifying patients with melanoma and regional nodal micrometastasis who may benefit from full nodal basin resection. To identify the pattern of tumor lymphatic drainage and the SLN, lymphoscintigraphy has been performed using primarily 99mTc-sulfur colloid (SC). In this study, we compare the efficacy of SLN biopsy using 99mTc-human serum albumin (HSA) with SLN biopsy after SC-based lymphoscintigraphy. METHODS: One hundred and six patients with localized cutaneous melanoma were studied. Lymphoscintigraphy was performed after intradermal injection of HSA in 85 patients and SC in 21 patients. Four patients underwent lymphoscintigraphy twice, once with SC and once with HSA. Dynamic images were acquired for up to 1 h, followed by high-count images of the SLN in various projections so that the most likely site was marked on the skin for biopsy. Intraoperatively, blue dye was injected around the primary site. Twenty-four patients underwent SLN dissection directed by preoperative lymphoscintigraphy and vital blue dye mapping; in the remaining 80 patients, a gamma probe was added intraoperatively to the localization procedure. Two patients underwent mapping with gamma probe alone. RESULTS: Draining lymphatic basins and nodes were identified by lymphoscintigraphy in all patients. The SLN was identified in 95% of patients when both blue dye and intraoperative gamma probe were used. When 99mTc-HSA was used for imaging, 98% of the SLNs ultimately identified were radiolabeled, and 82% were both hot and blue. Of the SLN recovered with SC, all the nodes were radiolabeled; however, there was only 58% hot and blue concordance. Greater numbers of SLNs were removed in the SC group (median 2.0 versus 1.0, P = 0.02); however, the incidence of micrometastasis was statistically similar in both HSA and SC cohorts. In the 4 patients examined with both tracers, SLN mapping was similar. CONCLUSION: Although SC has been the radiotracer of choice for SLN mapping in melanoma, HSA appears to be a suitable alternative, with identical success rates. In fact, the higher concordance between hot and blue nodes using HSA suggests superiority of this tracer for this purpose.

Immunohistochemistry with pancytokeratins improves the sensitivity of sentinel lymph node biopsy in patients with breast carcinoma.

BACKGROUND: Sentinel lymph node (SLN) biopsy is being investigated as a staging procedure for breast carcinoma. The authors evaluated whether immunohistochemical (IHC) analysis improves the sensitivity of this procedure. METHODS: Forty-four women with breast carcinoma were recruited for SLN biopsy. Preoperative lymphoscintigraphy was followed by intraoperative localization using a handheld gamma probe and blue dye. After SLN identification, an immediate complete axillary lymph node dissection was performed in all patients. All lymph nodes were subjected to routine histology (hematoxylin and eosin [H&E]) and IHC using antibody to cytokeratins. RESULTS: The SLN was identified in 41 of 43 patients (95%). Successful SLN identification was independent of biopsy technique (open surgical [95%] vs. fine-needle aspiration/core needle biopsy [96%]). Twelve of 41 patients (29%) had evidence of lymph node metastasis in the SLN by routine histology. Of the twenty-nine patients with H&E negative SLN, 3 were found to have metastasis by IHC for a conversion rate of 10%. Fifteen of 41 patients (37%) had evidence of metastasis in SLN. All 26 patients with H&E and IHC negative SLN had negative nonsentinel lymph nodes by routine histology and IHC (100% negative predictive value). All patients with tumors < 2 cm and micrometastasis to the SLN had no additional lymph node disease, in contrast to patients with lesions > 2 cm or patients with macrometastasis to the SLN (P = 0.007). CONCLUSIONS: These results confirm that SLN biopsy is extremely accurate for patients with breast carcinoma, even after open surgical biopsy. IHC analysis or serial sectioning of SLN improves the sensitivity of this staging technique.

Thyroid and parathyroid gland pathology. Role of imaging.

There are many imaging modalities available for studying thyroid and parathyroid masses. For the thyroid gland, the demonstration of a hyperfunctioning or purely cystic mass by scintigraphy and ultrasound reassures that a palpable nodule is not cancer. Solitary, cold, or solid nodules often requires biopsy because of suspicion of malignancy. Metabolic and inflammatory disorders are imaged best with nuclear medicine studies whereas congenital thyroid lesions are evaluated best with computed tomography or MR imaging. In the search for a parathyroid adenoma, MR imaging and technetium-99m sestamibi studies appear to be most accurate, but because of its low cost, ultrasound has a favorable role. In previously operated patients with persistent hyperparathyroidism, MR imaging is probably most useful, but multiple imaging studies may be needed for definitive localization of adenomas.