Intraoperative evaluation of sentinel lymph nodes for metastatic melanoma by imprint cytology

Diagnostic value of intraoperative histopathological examination of the sentinel nodes in breast cancer and skin melanoma-Preliminary results of single centre retrospective study

OBJECTIVE

Intraoperative histopatological examination of the sentinel nodes enables selection of patients who need dissection of the regional lymphatic system during the same operation. The aim of this study is to evaluate the diagnostic value of intraoperative histopathological examination of the sentinel nodes in breast cancer and skin melanoma. Intraoperative histopathology of the sentinel nodes as a diagnostic method is used in patients with melanoma and breast cancer. Recent studies have proved it to be an effective method for evaluating the nodes in the final histopathology. Intraoperative histopathological examination of the sentinel nodes is not performed routinely and there is no clear position on this issue. In this paper we try to prove that intraoperative test gives patients the simultaneous benefits of removal of regional lymph nodes metastases and earlier initiation of adjuvant therapy.

METHODS

The study comprises 137 patients with breast cancer and 35 patients with malignant skin melanoma. Sentinel nodes were intraoperatively sectioned and examined by means of the imprint method and frozen section evaluation. The patients with positive sentinel nodes underwent immediate dissection of regional lymph nodes. Those with negative sentinel nodes diagnosed in the intraoperative examination, but positive in final pathologic results, underwent subsequent dissection of regional lymph nodes.

RESULTS

60 sentinel lymph nodes were found in 35 patients with skin melanoma. In 3 patients, 3 sentinel lymph nodes were false negative in the intraoperative histopathological examination. No false positive sentinel lymph nodes were found. 249 sentinel lymph nodes were found in the intraoperative histopathological examination in 137 patients with breast cancer. There were no false positive sentinel nodes, but there were 7 false negative sentinel nodes. In this study, only 5 (3.6%) patients with breast cancer and 3 (8.5%) patients with skin melanoma required another regional operation.

CONCLUSION

The method of intraoperative histopathological evaluation of the sentinel nodes enables identification of metastases in these lymph nodes and gives a possibility to carry out a one-step regional lymphadenectomy and start the adjuvant therapy earlier.

Sentinel node biopsy for melanoma: an update after two decades of experience

When detected and treated early, melanoma has an excellent prognosis. Unfortunately, as the tumor invades deeper into tissue the risk of metastatic spread to regional lymph nodes and beyond increases and the prognosis worsens significantly. Therefore, accurately detecting any regional lymphatic metastasis would significantly aid in determining a patient's prognosis and help guide his or her treatment plan. In 1991, Don Morton and colleagues presented new paradigm in diagnosing regional lymphatic involvement of tumors termed sentinel lymph node biopsy (SLNB). By mapping the regional lymph system around a tumor and tracing the lymphatic flow, a determination of the most likely lymph node or nodes the cancer will spread to first is made. Then, a limited biopsy of the most likely nodes is performed rather than a more-invasive removal of the entire local lymphatic chain. In 20 years that have followed, a great deal of information has been gained as to its accuracy, prognostic value, appropriate candidates, and its impact on regional disease control and survival. The SLNB has been shown to accurately stage regional lymph node basins in stage I and II melanoma patients with minimal morbidity. More sensitive histologic techniques are now being applied that may allow even greater accuracy in the staging of melanoma patients. Although specific percent risk thresholds are still in question, recommendation for SLNB when melanomas are 1 mm or thicker has gained wide acceptance. SLNB may also be appropriate for patients with melanomas that are between 0.76 and 1 mm thick and have ulceration, high mitotic rates, or reach a Clark level IV. Therefore, melanomas with IB or greater staging should be considered for SLNB.

Intraoperative sentinel lymph node analysis in melanoma

BACKGROUND

The objective of this retrospective cohort study was to evaluate the sensitivity and specificity of touch preparation cytology (TPC) and frozen section (FS) histology in the intraoperative staging of melanoma.

METHODS

The cohort was identified from all patients with clinically node negative melanoma undergoing a SLN biopsy using Technetium and/or blue dye mapping from 1/1998 to 10/2008. TPC and FS analysis was performed utilizing Diff-quick and compared to permanent section interpretation with H&E.

RESULTS

Of 271 patients undergoing SLN biopsy, 163 underwent intraoperative analysis of the sentinel node (125 underwent TPC alone, 15 underwent FS alone, 23 underwent both TPC and FS), and 108 underwent no intraoperative analysis. Thirty-three patients undergoing intraoperative analysis of the SLN were found to have positive nodes (20%) on permanent histology. There were no false positives identified (specificity = 100%). The overall sensitivity for all methods of intraoperative analysis was 61% (20/33). On a per patient basis, the sensitivity was 47% (9/19) for TPC alone, 75% (3/4) for FS alone, and 80% (8/10) for both TPC and FS.

CONCLUSIONS

There were no false positives identified suggesting TPC and FS can be used safely to identify the majority of SLN that harbor metastases from melanoma.

Imprint cytology in tumor tissue bank quality control: an efficient method to evaluate tumor necrosis and to detect samples without tumor cells

Quality assessment of the tissue stored in a tumor biobank is crucial because it is estimated that approximately 10% of the frozen samples are unsuitable for a molecular analysis mainly because of sampling problems in the tissue. We studied the value of imprint cytology (IC) versus frozen section to quantify necrosis and tumor cells in the tissue. The amount of tumor cells and necrosis was assessed by one pathologist on the frozen sections and ICs independently on 100 consecutive tumor samples. It was expressed as a percentage on frozen sections and on a four-level semiquantitative scale for IC (0 to 3+). Overall agreement between the quantity of tumor cells on IC and on frozen section was fair (Kappa = 0.23). Sensitivity and specificity of IC to detect the absence of tumor cell on the frozen section were 57% (4/7) and 98% (91/93), respectively. Overall agreement between necrosis quantification on IC and on frozen section was substantial (Kappa = 0.66).Sensitivity and specificity of IC to detect significant necrosis (defined as more than 30% necrosis) were 100% (3/3) and 98% (95/97), respectively. We show that IC is efficient to semiquantify necrosis in a tumor sample and to detect significant necrosis. IC seems to be less efficient to quantify tumor cells.

Evaluation of sentinel lymph nodes for melanoma metastases by pathologists

The pathologic evaluation of sentinel lymph nodes for melanoma metastases is not without significant challenges. It is affected by significant variation in approaches, which may compromise the final interpretation, leading to nonrepresentative spurious results. This article discusses various approaches along with recommended dos and don'ts for optimum evaluation of sentinel lymph nodes for melanoma metastases.

Intraoperative Imprint Cytology for Evaluation of Sentinel Lymph Nodes from Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy. Intraoperative imprint cytology (IIC) can potentially avoid second operations for completion lymphadenectomy when nodal metastases are found during nodal staging with sentinel lymph node biopsy (SLN). This represents the first series of IIC for MCC we are aware of and our initial experience. Patients with biopsy-proven MCC underwent SLN (at the time of wide excision) using a double indicator technique with “technetium sulfur colloid and isosulfan blue. SLN were identified and bisected and touch imprints of each half were made. One half was air-dried and stained with Diff-Quick and the other was fixed with 95 per cent alcohol and stained with hematoxylin and eosin (H&E). Paraffin-embedded sections were examined by H&E. Eighteen patients underwent successful SLN mapping procedures. IIC was negative in 84.2 per cent (16) cases. Three false-negatives occurred with IIC, but there were no false-positives, making the sensitivity 33 per cent and the specificity 100 per cent. Two of four patients with positive pathology-confirmed SLN also had positive IIC. SLN mapping has usefulness in patients with MCC. IIC is feasible and accurate in evaluating the SLN. IIC is a practical diagnostic tool when intraoperative analysis of SLN biopsy is desired for MCC.

Real-time intraoperative detection of melanoma lymph node metastases using recombinant vaccinia virus GLV-1h68 in an immunocompetent animal model

There is a clinical need for improved intraoperative detection of lymph node metastases from malignant melanoma (MM). We aimed to investigate the use of recombinant vaccinia virus GLV-1h68, expressing green fluorescent protein (GFP), for real-time intraoperative detection of melanoma lymph node metastases in an immunocompetent animal model. Mice bearing foot pad tumors received intratumoral injections of GLV-1h68, and 48 hr later were evaluated for popliteal lymph node metastasis using noninvasive bioluminescence imaging and fluorescence imaging. Histologic analysis of lymph nodes was performed to determine sensitivity and specificity of virus-mediated detection. Intratumoral injection of GLV-1h68 into primary foot pad melanoma tumors resulted in viral transmission to popliteal lymph nodes, infection of lymphatic metastases, and transgene expression that was reliably and easily detected. Histologic confirmation demonstrated favorable operating characteristics of this assay (sensitivity 80%, specificity 100%, positive predictive value [PPV] 100%, negative predictive value [NPV] 91%). Detection of marker gene expression by GLV-1h68 allowed the detection of lymphatic metastases in an immunocompetent animal model of MM. This assay is rapid, sensitive, specific and easy to perform and interpret. As a candidate gene therapy virus for killing cancer, GLV-1h68 may also have significant concomitant diagnostic utility in the staging of cancer patients.