The amount of metastatic melanoma in a sentinel lymph node: does it have prognostic significance?

Prediction of non-sentinel node status and outcome in sentinel node-positive melanoma patients

AIMS

Sentinel lymph node (SLN) -positive melanoma patients are usually recommended completion lymph node dissection (CLND) with the aim to provide regional disease control and improve survival. Nevertheless, only 20% these patients have additional metastases in non-sentinel lymph nodes (NSLN), indicating that CLND may be unnecessary in the majority of patients. In this retrospective study, we (i) sought to identify clinico-pathological features predicting NSLN status, as well as disease-free (DFS) and -specific (DSS) survival and (ii) evaluated the applicability of previously published algorithms, which were able to define a group of patients at zero-risk for NSLN-metastasis.

METHODS

This analysis included 504 consecutive melanoma patients stage I and II who underwent successful SLN-biopsy (SLNB) at our institute between 1998 and 2005. Metastatic SLN were re-evaluated for tumor burden and categorized according to two different micro-anatomic classifications and the S/U-score (Size of the sentinel node metastasis > 2 mm/Ulceration of the primary melanoma) was assessed. DFS and DSS were calculated for all analyses.

RESULTS

Out of 504 melanoma patients stage I or II, 85 (17%) were SLN-positive and 18 of 85 (21%) were found with positive NSLN in the CLND specimen. Median follow-up was 31 months. Neither primary tumor characteristics (age, gender, Clark level, Breslow thickness, ulceration of the primary melanoma, site and histological subtype of the primary melanoma), nor features of the sentinel node tumor (number and site of draining lymph node basins, number of positive sentinel nodes and size of sentinel node tumor (< 2 mm vs. > or = 2 mm) were able to predict additional positive lymph nodes in the CLND specimen. Likewise the implementation of published algorithms was not able to identify patients at negligible risk for harboring NSLN metastases. Upon univariate analysis, disease-free survival in SLN-positive patients was correlated with Breslow thickness, sentinel node tumor size > 2 mm and S/U score. In respect to disease-specific survival the significant prognostic parameters were Breslow thickness, ulceration, sentinel node tumor size > 2 mm and the S/U score. After a median follow-up of 31 months recurrence rates (37% vs. 78%, p=0.02) and death from disease (24% vs. 50%, p<0.01) were significantly different in patients with SLN-metastasis only as compared to patients with NSLN-metastasis.

CONCLUSION

NSLN status cannot be predicted in this data analysis by using clinico-pathological characteristics. Therefore, CLND is recommended for all patients after positive SLNB pending the results of the second Multicenter Selective Lymphadenectomy Trial.

Influence de la taille et de la localisation des métastases dans les ganglions sentinelles de mélanome sur le résultat du curage, à propos de 35 cas

AIM

Thirty-five cases of lymphadenectomy carried out in the context of positive sentinel lymph node for malignant melanoma have been reviewed to assess the prognostic value of certain metastatic charachteristics. We have checked wether the type (macro or micrometastasis) and localisation (subcapsular or intraparenchymal) in the sentinel lymph node had predictive value for the lymphadenectomy outcome and evolution of the case.

MATERIAL AND METHODS

The retrospective study relates to 35 cases (with an average 2 years history) taken from a total of 87 sentinel lymph node protocols; average age 46.5 years, Breslow 2.5 mm with an history of 25 months.

RESULTS

Among the 35 positive sentinel lymph nodes we have 19 cases (54.2%) of micrometastasis. Among the 35 lymphadenectomy 5 cases (14.28%) turned out positive, 3 of which concerned micrometastatic sentinel lymph nodes. In our cohort the micrometastatic nature of sentinel lymph nodes did not have statistically significant impact upon the lymphadenectomy result but showed more favourable short-term evolution with 68.42% metastatic free evolution as against 43.75% in case of initial macrometastasis. The subcapsular localisation of micrometastasis equally represents a factor of improved prognosis (69.2% of metastatic free evolution against of 30.8% in the case of intraparenchymal localistion).

CONCLUSION

Unfortunately, none of the studied criteria justifies a modification of our present clinical attitude whereby a systematic lymphadenectomy in cases of positive sentinel lymph nodes is performed, whatever the type or localisation of the relevant metastases.

Size of sentinel node metastases predicts other nodal disease and survival in malignant melanoma

BACKGROUND

A positive sentinel lymph node (SLN) biopsy is an indication for completion lymph node dissection (CLND) in malignant melanoma; however, most CLNDs are negative. We hypothesized SLN metastatic size of < or =2 mm would predict CLND status and prognosis.

METHODS

We evaluated 80 consecutive patients undergoing CLND for positive SLNs over a 10-year period. Incidence of positive nonsentinel nodes and survival were compared for patients with SLN metastases < or =2 mm and >2 mm.

RESULTS

Of 504 patients undergoing SLN biopsy, 49 patients had SLN deposits < or =2 mm and a 6% incidence of positive CLNDs. Five-year survival was 85%, essentially the same as negative SLN biopsies. In contrast, 31 had SLN metastases >2 mm, a 45% incidence of addition disease at CLND, and 5-year survival of 47% (P < .0001).

CONCLUSION

An SLN metastatic cut point of 2 mm is an efficient predictor of CLND status and survival in malignant melanoma.

Histological features of melanoma sentinel lymph node metastases associated with status of the completion lymphadenectomy and rate of subsequent relapse

BACKGROUND

The current recommendation for patients with cutaneous melanoma and a positive sentinel lymph node (SLN) biopsy is a completion lymph node dissection (CLND). This study sought to define a population of SLN-positive patients, based on their histological pattern of SLN metastases, who may not require CLND.

METHODS

All patients with SLN-positive cutaneous melanoma who underwent CLND between March 1999 and December 2004 at a single academic institution were enrolled. Metastatic deposits in the SLN were categorized by their histological zone of involvement (subcapsular, parenchymal and/or sinusoidal). Logistic regression was used to examine the effect of SLN zone, size of nodal metastases, and other histological factors on CLND positivity. Kaplan-Meier and Cox models were used to study disease recurrence.

RESULTS

A total of 127 patients were included, and 15.8% had positive non-sentinel nodes. In adjusted analyses, the size of the largest tumor deposit in the SLN was the only factor associated with CLND status. No patients with a tumor deposit <or=0.20 mm had a positive CLND. Although a specific zone of tumor involvement was not predictive of CLND status, involvement of all three zones was independently associated with increased recurrence. Size of the largest tumor deposit was also associated with recurrence, with no recurrences in patients with nodal deposits <or=0.20 mm.

CONCLUSION

Histologic features of tumor metastases in positive SLN may be useful in defining a population of patients who may be spared CLND and a group at high risk of recurrence.

Clinical relevance of melanoma micrometastases (<0.1 mm) in sentinel nodes: are these nodes to be considered negative?

As only about 20% of sentinel node (SN) positive melanoma patients have additional non-SN lymph node involvement in the Completion Lymph Node Dissection (CLND) specimen, we tried to identify a SN positive patient group, which can be spared CLND. Micro anatomic analyses of metastatic SNs were performed to identify patient/tumor and/or SN factors predicting additional non-SN positivity as well as disease-free and overall survival. SN positivity was found in 77 of 262 stage I/II patients, included into a prospective database (10/97-5/04). Of 74 patients pathology material was available for re-evaluation. Micro anatomic analyses categorized topography of SN-metastases, Starz classification and amount of SN tumor burden. Additional non-SN positivity, DFS, OS and was calculated for all analyses. Mean Breslow thickness was 3.5 mm (0.8-12.0); mean FU was 35 (6-81) months. There was no additional non-SN positivity for SN-micrometastases <0.1 mm. Topography of SN involvement had no impact on OS. Estimated 5-year OS rates for the different groups of <0.1 mm, 0.1-1.0 mm and >1.0 mm SN tumor burden were 100%, 63% and 35% respectively. Distant metastases were exceedingly rare (1/16 = 6.3%) in <0.1 mm SN-positive patients. On multivariate analysis the SN tumor burden was the most important prognostic factor for DFS (P = 0.005) and OS (P = 0.03). Distant metastasis-free survival was identical (91%) to the 5-yr OS of SN negative patients, the estimated 5-yr OS was 100% for these patients and additional non-SN positivity was not observed. Therefore, our data suggest that patients with sub-micrometastases (<0.1 mm) in the SN may be judged as SN negative, as non-stage III, and are highly unlikely to benefit from CLND, which we no longer recommend.

Molecular diagnostics in melanoma

Molecular pathology is rapidly evolving, featuring continuous technologic improvements that offer novel clinical opportunities for the recognition of disease predisposition, for identifying sub-clinical disease, for more accurate diagnosis, for selecting efficacious and non-toxic therapy, and for monitoring of disease outcome. Currently, the identification and prognosis of primary cutaneous melanoma is based on histologic factors (tumor depth and ulceration) and clinical factors (number of lymph node and/or distant metastases). However, metastasis can occur in patients with thin melanomas, and sentinel lymph node biopsy does not identify all patients at risk for distant metastasis. New markers exist that correlate with melanoma progression, which may aid in melanoma identification, prognostication, and detection of minimal residual disease/early recurrence. Moreover, not many therapeutic options exist for melanoma as no regimen prolongs survival. Emerging data with investigational therapies suggest that certain markers might play a crucial role in identifying patients who will respond to therapy or show utility in the monitoring the response to therapy. Herein, molecular diagnostics that can potentially benefit the individual melanoma patient will be discussed.

Surgical Management of Primary Cutaneous Melanoma: Excision Margins and the Role of Sentinel Lymph Node Examination

Surgical strategies for managing patients who have primary cutaneous melanoma have changed dramatically over the past 30 years. More conservative excision margins have been shown to be adequate, and routine complete lymph node dissection (CLND)has been abandoned since the sentinel node (SN) biopsy technique was introduced. Knowledge of a patient's SN status not only provides a reliable guide to prognosis, but also allows CLND to be avoided in 80% to 85% of patients. Recent clinical trial results suggest that SN biopsy, with immediate CLND if an SN is positive,confers a survival advantage in those who have metastatic disease in regional nodes. Minimally invasive and noninvasive methods of SN assessment, such as magnetic resonance spectroscopy, are being evaluated.

High positive sentinel node identification rate by EORTC melanoma group protocol. Prognostic indicators of metastatic patterns after sentinel node biopsy in melanoma

Methods to work-up sentinel nodes (SN) vary considerably between institutes. This single institution study evaluated the positive SN-identification rate of the EORTC Melanoma Group (MG) protocol and investigated the prognostic value of the SN status regarding disease-free survival (DFS) and overall survival (OS) and evaluated the locoregional control after the SN procedure. Multivariate and univariate analyses using Cox's proportional hazard regression model was employed to assess the prognostic value of covariates regarding DFS and OS. The positive SN-identification rate was 29% at a median Breslow thickness of 2.00 mm and the false-negative rate was 9.4%. Breslow thickness and ulceration of the primary correlated with SN status. SN status, ulceration and site of the primary tumour correlated with DFS. SN status and ulceration of the primary correlated with OS. The in-transit metastasis rate correlated with SN-positivity, Breslow thickness and ulceration. Projected 3-year OS was 95% in SN-negative and 74% in SN-positive patients. Transhilar bivalving of the SN with step sections from the central planes is simple and had a high SN-positive detection rate of about 30%. The SN status is the most important predictive value for DFS and OS. In-transit metastasis rates correlated with SN-positivity, Breslow thickness and ulceration of the primary.

Molecular staging of the sentinel lymph node in melanoma patients: correlation with clinical outcome

BACKGROUND

This study was designed to determine the debated prognostic significance of reverse transcriptase-polymerase chain reaction (RT-PCR) positivity in melanoma patients' sentinel lymph node (SLN) negative by conventional histopathology (PATH).

PATIENTS AND METHODS

Patients with primary stage I-II cutaneous melanoma underwent radioguided sentinel lymphadenectomy. Their SLNs were assessed for tyrosinase (Tyr) and melanoma antigens recognized by T-cells (MART-1) mRNA expression using RT-PCR, in parallel with hematoxylin and eosin staining and immunohistochemistry. Tyr and MART-1 expression in the SLNs were correlated with PATH assay results, standard prognostic factors, time to progression and overall survival.

RESULTS

Twenty-three of the 124 patients (18.5%) had positive SLNs by both PATH and RT-PCR (PATH+/PCR+). Sixteen patients (13%) were negative by PATH and positive by RT-PCR (PATH-/PCR+). Eighty-five patients (68.5%) had SLNs that were negative by both PATH and RT-PCR (PATH-/PCR-). At a median follow-up of 30 months, recurrence rates among the three cohorts were statistically different (PATH+/PCR+, 60%; PATH-/PCR+, 31%; PATH-/PCR-, 9.4%). Seven of 23 (30%) and two of 16 (12.5%) patients died in the PATH+/PCR+ and PATH-/PCR+ SLN groups, respectively, whereas no patient died in the PATH-/PCR- SLN group.

CONCLUSIONS

RT-PCR is more sensitive than PATH to detect SLN metastases and it is a reliable predictor of disease relapse in stage I-II melanoma patients.

Erfahrungen mit der neuen American Joint Committee on Cancer (AJCC)-Klassifikation des kutanen malignen Melanoms. Experiences with the new American Joint Committee on Cancer (AJCC) classification of cutaneous melanoma

A new AJCC/UICC staging classification of malignant melanoma was published in 2001 and has been in use since then. Compared to the TNM classification used for the previous 15 years, the new classification contains fundamental changes. The classification of the primary tumor is now based on newly defined classes for Breslow's tumor thickness (0 - 1.0 mm; 1.01 - 2.0 mm, 2.01 - 4.0 mm; > 4.0 mm). Histopathologically diagnosed ulceration is the second prognostic factor in primary melanoma and its presence leads to upstaging into the next higher T category. Clark level of invasion is now only relevant for tumors up to 1 mm thick; levels IV and V are also reasons for upstaging. Classification of regional lymph node metastasis distinguishes between microscopic metastasis only as detected with sentinel lymph node biopsy and clinically detectable macroscopic metastasis. Additionally, the number of metastatic nodes and the presence of satellite and in-transit metastasis are prognostic factors for classification of regional lymph node metastasis. In distant metastasis, the kind of organ involvement has a role for classification (only skin and lymph nodes vs. lung vs. other organs) and an elevated LDH value leads to upstaging. A critical analysis of data of the German Central Malignant Melanoma Registry did not confirm the strong role of histopathological ulceration of the primary tumor in all T- and N-stages. Furthermore, there is an inconsistency of the classification as stage IIC displays a significantly worse prognosis as compared to stage IIIA. In spite of these drawbacks the new staging classification should used particularly in clinical trials in order to make data internationally comparable.

Predictors and Natural History of In-Transit Melanoma After Sentinel Lymphadenectomy

BACKGROUND

In-transit recurrence is a unique and uncommon pattern of treatment failure in patients with melanoma. Little information exists concerning the incidence, predictors, and natural history of in-transit disease since the introduction of sentinel lymph node biopsy (SLNB).

METHODS

Between 1991 and 2001, 1395 patients with primary melanoma underwent SLNB. Univariate and multivariate logistic regression analyses were performed to examine the association among known clinicopathologic factors, in-transit recurrence, and distant metastatic failure after the development of in-transit disease.

RESULTS

With a median follow-up of 3.9 years, 241 patients (17.3%) experienced disease recurrence, including 91 (6.6%) who developed in-transit recurrence. Independent predictors of in-transit recurrence included age >50 years, a lower extremity location of the primary tumor, Breslow depth, ulceration, and sentinel lymph node (SLN) status. Of the 69 patients who presented with in-transit disease as the sole site of first recurrence, 39 developed distant disease. By univariate analysis, predictors of distant failure among patients with in-transit disease included SLN status, largest metastatic focus in the SLN >2.5 mm2, subcutaneous location of in-transit disease, in-transit tumor size > or = 2 cm, and a disease-free interval before in-transit recurrence of <12 months. In-transit tumor size remained a significant predictor of distant metastasis by multivariate analysis (odds ratio, 9.69).

CONCLUSIONS

The overall incidence of in-transit metastases in patients undergoing SLNB is low and does not seem to have increased since the introduction of the SLNB technique. In-transit recurrence, as well as subsequent distant metastatic failure, can be predicted on the basis of adverse tumor factors and SLN status.

Evidence-based principles and practices in pathology: selected problem areas

Contrary to the intuitive impression of most pathologists, there are still many areas in laboratory medicine where evidence-based medicine (EBM) principles are not applied. These include aspects of both anatomic and clinical pathology. Some non-EBM practices are perpetuated by clinical "consumers" of laboratory services, because of inadequate education, habit, or over-reliance on empirical factors. Other faulty procedures are pathologist-driven, with similar underpinnings. This overview considers several exemplary problem areas representing non-EBM practices in the hospital laboratory. Such examples include ideas and techniques centering on metastatic malignancies, "targeted" oncological therapy, analysis of surgical margins in the excision of neoplasms, general laboratory testing and data utilization, evaluation of selected coagulation defects, administration of blood products, and analysis of hepatic iron-overload syndromes. The concepts illustrating departures from EBM are discussed for each of those topics.

Sentinel node status in melanoma patients is not predictive for overall survival upon multivariate analysis

Sentinel lymph node biopsy (SLNB) has become a widely accepted standard procedure in the staging of patients with cutaneous melanoma and absence of clinical lymph node metastases, although there is no final proof that SLNB influences overall survival in these patients. This study investigated the accuracy of SLNB and the clinical outcome of patients after a mean follow-up of 22 months. Between 1998 and 2003, SLNB was performed in 309 consecutive patients. Patients with one or more positive sentinel lymph nodes (SLNs) were subjected to selective lymphadenectomy (SL). Survival analyses were performed using the Kaplan–Meier approach. A Cox proportional-hazard analysis was used for univariate and multivariate analysis to explore the effect of variables on survival. Sentinel lymph nodes were identified in 299 of 309 patients (success rate: 96.8%). Of these, 69 (23%) had a positive SLN. The false-negative rate was 9.2%. Recurrence of disease to the regional lymph node basin (3.0%) and to the locoregional skin (2.6%) was rare in SLN-negative patients in contrast to SLN-positive patients (7.2 and 17.4%, respectively). The 3-year overall survival was 93 and 83% for SLN-negative and SLN-positive patients, respectively. Upon multivariate analysis, SLN status (P<0.001), Breslow thickness (P<0.02) and ulceration (P<0.026) were all found to be independent prognostic factors with respect to disease-free survival, whereas Breslow thickness proved to be the only significant factor with respect to overall survival.

Ultrasound examination of sentinel nodes in the initial assessment of patients with primary cutaneous melanoma

BACKGROUND

The value of targeted high-resolution ultrasound (US) examination in detecting sentinel lymph node metastases in patients with newly diagnosed primary cutaneous melanomas has not yet been fully evaluated. The aim of this study was to determine the threshold size of metastatic melanoma deposits in SLNs able to be detected by targeted US examination before initial melanoma surgery.

METHODS

A total of 304 patients presenting with primary cutaneous melanomas had SLNs identified by lymphoscintigraphy and then examined in situ by the same physician with high-resolution US. Within 24 hours, the SLNs were removed for histopathologic assessment of sections stained conventionally and with immunohistochemical markers for S100 protein and HMB45 antigen.

RESULTS

Metastatic disease was present in SLNs from 33 node fields in 31 patients. The US results in seven of these cases were suggestive of metastatic disease. Twenty-six node fields contained positive nodes not detected by US. Undetected deposits had diameters <4.5 mm.

CONCLUSIONS

These results suggest that a targeted US examination of SLNs can detect metastatic melanoma deposits down to approximately 4.5 mm in diameter. However, most metastatic melanoma deposits in SLNs are considerably smaller than this at the time of initial staging, and US therefore cannot be considered cost-effective in this setting.

CCL21 chemokine regulates chemokine receptor CCR7 bearing malignant melanoma cells

PURPOSE

The chemokine CC-ligand 21/secondary lymphoid tissue chemokine (CCL21/SLC) regulates the homing of naïve T cells and dendritic cells that express CC-chemokine receptor 7 (CCR7) from distant sites to lymphoid tissue such as lymph nodes. We hypothesized that CCL21/SLC regulates the migration of CCR7-bearing melanoma cells from a primary lesion to regional tumor-draining lymph nodes.

EXPERIMENTAL DESIGN

Quantitative real-time reverse transcriptase-PCR (qRT) assay and immunohistochemistry (IHC) were used to assess the level of CCR7 expression in melanoma cell lines and in primary and metastatic melanoma tumors. Cell migration assay using melanoma cell lines was performed under the induction of CCL21/SLC. The CCL21/SLC expression level in tumor-draining sentinel lymph nodes (SLNs) was assessed by both qRT assay and IHC.

RESULTS

Melanoma cell lines and tumors demonstrated heterogeneous expression of CCR7 mRNA by qRT assay. There was strong functional correlation between CCR7 mRNA expression and cell migration induced by CCL21/SLC. IHC evidence of CCR7 expression in primary melanomas significantly (P = 0.02) correlated with Breslow thickness. Assessment of SLN from 55 melanoma patients by qRT assay demonstrated that CCL21/SLC mRNA expression level was significantly (P = 0.008) higher in pathologically melanoma-negative SLNs than in melanoma-positive SLNs.

CONCLUSIONS

This report demonstrates a potential mechanism for recruitment and homing of CCR7(+) metastatic melanoma cells to tumor-draining lymph nodes, which express CCL21/SLC. The study also suggests that lymph nodes bearing metastasis may suppress CCL21/SLC production.

Melanoma - what is new in sentinel node biopsy and locoregional treatments in 2003? Report of a workshop at the Third Research Meeting on Melanoma, Milan, Italy, May 2003

This paper reports on the scientific session on sentinel node biopsy, surgery and locoregional treatments that took place during the Third Research Meeting on Melanoma, Milan, Italy, held in May 2003. It provides an overview of contributions presented at the meeting grouped according to subject - ultrasound scanning, sentinel node biopsy, mini-invasive surgery and stop-flow limb perfusion. The main comments made by the respective rapporteurs are also summarized.

The microanatomic location of metastatic melanoma in sentinel lymph nodes predicts nonsentinel lymph node involvement

PURPOSE

Sentinel node biopsy is now widely accepted as the most accurate prognostic indicator in melanoma, and is important in guiding management of patients with clinical stage I or II disease. Patients with a positive sentinel node have conventionally undergone completion lymphadenectomy (CLND) of the involved basin, but only 20% have involvement beyond the sentinel node, suggesting that CLND may be unnecessary for the other 80% of patients. This study seeks to identify criteria that might be used to be more restrictive in selecting those who should undergo CLND.

METHODS

A total of 146 patients were identified who had had a positive sentinel node biopsy for malignant melanoma. Their sentinel nodes and lymphadenectomy specimens were re-evaluated pathologically. The metastatic melanoma in each sentinel node was assessed according to its microanatomic location within the node (subcapsular, combined subcapsular and parenchymal, parenchymal, multifocal, or extensive), and this was correlated with the presence of involved nonsentinel nodes in the CLND. The depth of the metastases from the sentinel node capsule was also recorded.

RESULTS

The metastatic deposits in the sentinel node were subcapsular in 26.0% of patients. None of these patients had any nonsentinel nodes involved on CLND. In the patients whose sentinel node metastases had a different microanatomic location, the rate of nonsentinel node involvement was 22.2% overall.

CONCLUSION

The microanatomic location of metastases within sentinel nodes predicts nonsentinel lymph node involvement. In patients with only subcapsular deposits in the sentinel node, it is possible that CLND could safely be avoided.

Prediction of metastatic melanoma in nonsentinel nodes and clinical outcome based on the primary melanoma and the sentinel node

Lymphatic mapping and sentinel node biopsy are well-established techniques for staging and managing patients with melanoma, breast cancer and other malignancies that spread initially to the regional lymph nodes. Identification of tumor in the sentinel node is the most precise staging technique currently available. The sentinel node is the site of metastatic melanoma in approximately 20% of melanoma patients and if tumor is present in the sentinel node it is customary to perform a complete dissection of the lymph nodes of the affected nodal basin. This may be overtreatment for some patients as tumor is identified in the nonsentinel nodes of only one-third of sentinel node-positive melanoma patients treated by completion lymphadenectomy. If it were possible accurately to identify the minority of patients with tumor in the nonsentinel nodes, the patients most likely to benefit from lymphadenectomy, the remaining patients could be spared a potentially morbid operation that is unlikely to confer clinical advantage. In 90 patients with a melanoma-positive sentinel node, who subsequently had a completion lymphadenectomy, we evaluated and compared the capacity of characteristics of the primary melanoma and of the sentinel node to predict individuals likely to have tumor in nonsentinel nodes. We assessed the Breslow thickness of the primary, the amount of tumor in the sentinel node (relative tumor area) and, as an index of immune modulation of the sentinel node, the density of dendritic leukocytes in the nodal paracortex. The relative area of tumor in the sentinel node and Breslow thickness of the primary melanoma most accurately predicted the presence of tumor in the nonsentinel nodes (P=0.0001 in both cases-Wilcoxon rank sums). The presence of melanoma in the nonsentinel nodes was also predicted by the density of dendritic leukocytes in the paracortex (P=0.008-Wilcoxon rank sums). These three observations assessed alone and in combination predict the presence of tumor in the nonsentinel nodes with high accuracy. The same characteristics also significantly correlated with tumor recurrence (tumor burden, P=0.0001, Breslow, P=0.0001 and dendritic cell density, P=0.0007) and death from melanoma (tumor burden, P=0.0001, Breslow, P=0.0001 and dendritic cell density, P=0.0026).

Sentinel lymph node dissection in stage I/II melanoma patients: surgical management and clinical follow-up study

Selective sentinel lymph node (SLN) dissection is widely used in the management of cutaneous melanoma patients without clinical evidence of nodal metastases. A series of 274 consecutive melanoma patients who underwent melanoma primary excision and SLN mapping at our institutions since 1998, and were thereafter followed up and eventually treated, is reported in this prospective study. The aim was to analyse the parameters associated with a higher risk of occult nodal metastases, to evaluate the clinical outcome of melanoma patients who underwent SLN procedure, and to identify by means of multivariate analysis the prognostic parameters with independent predictive value on disease-free survival (DFS) in node-positive and negative patients. The SLN was tumour-negative in 228 patients (83.2%). A disease progression occurred in 25 (10.9%); among them, 10 patients in whom the initially identified SLN had been negative, developed a clinically and histologically evident positive lymph node in the same basin during follow-up. Five-year DFS and overall survival were 75% and 82%, respectively. In 46 patients (16.8%), the SLN proved to be tumour positive. The percentage of SLN-positive patients varied according to the primary thickness, from 11.8% in patients with Breslow of 2 mm or lower, to 34.7% in patients with Breslow from 2 to 4 mm, up to 55.9% in patients with Breslow greater than 4 mm (P<0.001). Only two patients with Breslow thickness lower than 1 mm had positive SLN biopsy. Five-year DFS and overall survival (OS) were 42 and 69%, respectively, significantly lower than those of negative SLN-patients (P<0.001). Multivariate analyses showed that the parameters with prognostic independent value on DFS were SLN status (micrometastases or macrometastases; P=0.0001), and to a lesser extent, Breslow thickness (P=0.04). In conclusion, our data support the clinical usefulness of SLN dissection as a reliable and accurate staging method in patients with cutaneous melanoma. SLN-positive patient OS (5-year survival 69%) seems to be superior to that historically reported for stage III patients treated with curative nodal dissection only after the clinical evidence of palpable adenopathies (5-year survival 36%). The prognostic relevance of the pattern of SLN invasion (micrometastases/macrometastases) could be the basis for the planning of adjuvant treatment trials on selected groups of patients.

Sentinel lymph nodes in malignant melanoma

BACKGROUND

The optimal technique for sentinel lymph node (SN) assessment in patients with melanoma is controversial. Molecular analysis (reverse transcriptase-polymerase chain reaction) detects significantly greater numbers of SNs with suspected micrometastases (up to 71%) than does routine histopathology (approximately 20%). The authors sought to identify possible reasons for this discrepancy and to determine whether using an extended histopathologic protocol could improve diagnostic precision.

METHODS

Two hundred thirty-one SNs from 100 consecutive patients with cutaneous melanomas that measured 1-4 mm in thickness were bisected, and half of the lymph node was examined according to an extensive histopathologic protocol involving serial sectioning and immunohistochemical analysis of 3 melanocyte-associated markers (S-100, HMB-45, and Melan-A).

RESULTS

Lymph node melanocytic lesions were frequent, with micrometastases and benign nevus inclusions (BNI) found in SNs in 28% and 28% of patients, respectively (4 SNs contained both). Melan-A was the most sensitive immunohistochemical marker and was positive in all BNI-positive SNs and 97% of micrometastasis-positive SNs. Although HMB-45 showed differential labeling in micrometastases compared with BNI (82% vs. 16%), immunohistochemistry could not distinguish between those lesions. Micrometastases were already identified on the first central level in 49% of positive SNs, whereas only 23% of SNs with BNI were diagnosed on the first level.

CONCLUSIONS

Extensive serial sectioning with immunohistochemical analysis substantially increased the histopathologic detection of micrometastases and BNI in melanoma SNs to a level approaching the level reported for molecular techniques. The large number of BNIs represents an important potential source of imprecision (false positivity) in SN assays based on nonmorphologic methods.