Sentinel lymph nodes in cutaneous melanoma: handling, examination, and clinical repercussion

Sentinel lymph node assessment in melanoma: current state and future directions

Assessment of sentinel lymph node status is an important step in the evaluation of patients with melanoma for both prognosis and therapeutic management. Pathologists have an important role in this evaluation. The methodologies have varied over time, from the evaluation of dimensions of metastatic burden to determination of the location of the tumour deposits within the lymph node to precise cell counting. However, no single method of sentinel lymph node tumour burden measurement can currently be used as a sole independent predictor of prognosis. The management approach to sentinel lymph node-positive patients has also evolved over time, with a more conservative approach recently recognised for selected cases. This review gives an overview of past and current status in the field with a glimpse into future directions based on prior experiences and clinical trials.

Variability of Sentinel Lymph Node Location in Patients with Trunk Melanoma

(1) Background: Melanoma is one of the most aggressive types of neoplasia, and the management of this pathology requires a correct staging, as well as a personalized modern oncological treatment. The main objective of the study is to determine the variability of the lymphatic drainage for patients with melanomas located on the trunk and, secondarily, to determine the features of individuals who underwent sentinel lymph node biopsy (SLNB) depending on the exact location on the trunk. (2) Methods: This retrospective, observational, single-center study included 62 cases of trunk melanoma operated between July 2019 and March 2023, in which SLNB was performed and a total of 84 lymph nodes were excised. (3) Results: Patients had a median age of 54.5 (33-78) years, with 58.1% being male; the melanomas had a median Breslow index of 2.3 (0.5-12.5) mm. Approximately 64.3% of the cohort had melanoma on the upper part of the trunk (54 cases) and 35.7% had it on the lower part (30 cases). The type of anesthesia chosen was general anesthesia in 53 cases and spinal anesthesia in 9 cases (85.5% vs. 14.5%, p < 0.001). The number of sentinel lymph nodes excised was 54 for melanomas located on the upper part of the trunk (8 cervical and 46 axillary) and 30 sentinel lymph nodes for melanomas of the lower part of the trunk (16 at the axillary level and 14 at the inguinal level). Out of the 54 LNs identified in patients with melanoma on the upper part of the trunk, 13 were positive, with a total of 12 positive lymph nodes (LNs) from the axillar basin, and only one from the cervical region. Additionally, the incidence of patients with a minimum of two identified sentinel lymph nodes was 32.2%, with a total of seven having LN involvement in two basins, and only one of these cases showed positivity for malignancy. (4) Conclusions: SLNBs were more frequent in the axillary region overall, and had more positive SLNs. Moreover, melanoma on the upper part of the trunk had a higher rate of positive SLNs compared to the lower part. Tumors located on the lower part of the truck had more positive SLNs in the axillary region than in the inguinal one.

Differentiation of benign nevoid rests and metastatic melanoma in sentinel lymph node biopsy

Patients with cutaneous melanoma routinely undergo sentinel lymph node (SLN) biopsy. If this first lymph node is clear, the entire lymph node basin is very likely to be free from the metastatic disease. Lymph node analysis is therefore of great importance with respect to prognostication and further management. Various cell types, including benign nevoid rests, can mimic metastatic melanomatous cells in the SLN. There is no standardized method to differentiate naevoid rests from metastatic melanoma. Diagnosis is based on cell location, morphology and multiple immunohistochemical techniques, with no single test being completely diagnostic. We present a patient with Lentigo Maligna melanoma, who was found to have benign nevoid rests on SLN biopsy, and discuss the diagnostic tests and considerations in differentiating benign nevoid rests from metastatic melanoma.

The EORTC protocol for sentinel lymph node biopsy (SLNB) reveals a high number of nodal nevi and a strong association with nevus-associated melanoma

BACKGROUND

The diagnosis of nodal nevi (NN) is challenging as they mimic melanoma metastases (MM), with a detection rate mostly ranging between 1% and 11% in sentinel lymph node biopsy (SLNB). Herein, we assessed the incidence of NN and the association with the clinical-pathological features of primary melanoma, adopting the updated European Organisation for Research and Treatment of Cancer (EORTC) protocol for SLNB.

METHODS

All cases of paired melanoma and SLNB were retrospectively evaluated (April 2019-May 2020). Appropriate statistical tests were adopted, with significant variables included in the logistic regression model.

RESULTS

81 patients and a total of 186 lymph nodes (LNs) were included. Eleven patients had only NN and 4 had both NN and MM (18.5%); 29 LNs (15.6%) showed at least one NN and 12 (6.5%) showed more than one NN (a total amount of 43 NN was detected). All NN and none MM stained for p16. NN were associated with age < 60 years (p: 0.042), no ulceration (p: 0.025) and nevus-associated melanoma (NAM) (p: 0.018), with this latter being the only predictor at the logistic regression model (p: 0.022).

CONCLUSIONS

The updated EORTC protocol shows a high number of NN and highlights a strong association with NAM.

Hematoxylin and eosin or double stain for CD34/SOX10: Which is better for the detection of lymphovascular invasion in cutaneous melanoma?

BACKGROUND

Lymphovascular invasion (LVI) is considered an unfavorable prognostic factor in cutaneous melanoma (CM). However, its detection by hematoxylin and eosin (H&E) is challenging, with discordant data about its association with clinical-pathological features and no previous studies investigating the inter- (IrOA) and intra-observer (IaOA) agreement. Herein, we tested H&E and double staining (DS) for CD34/SOX10 to detect the LVI in a cohort of 92 CMs, evaluating the IrOA, the IaOA, and the association with the other clinical-pathological features.

METHODS

Five authors independently evaluated 92 consecutive and retrospectively enrolled cases of CMs. We assessed the IrOA (Fleiss's Kappa/FK and intraclass correlation coefficient/ICC) and the IaOA (Cohen's Kappa/CK) with both H&E and CD34/SOX10. Furthermore, we compared the LVI assessment with the two stains and analyzed the association with other clinical-pathological features [χ2 tests for dichotomous and categorical data; Student t-test (normal distribution) and Mann-Whitney U-test (non-normal distribution) for continuous data].

RESULTS

The IrOA was almost identical with H&E (FK=0.446; ICC=0.805) and CD34/SOX10 (FK=0.454; ICC=0.810); by contrast, the IaOA was higher with H&E for one pathologist (CK: 0.809) and with CD34/SOX10 for the other one (CK: 0.563). Applying previously defined criteria, LVI was detected in 10 (9.2%) and 11 (10.1%) cases with H&E and CD34/SOX10, respectively (p = 1.000). Both H&E and CD34/SOX10 were significantly associated with vertical growth phase (H&E, p: 0.014; CD34/SOX10, p: 0.010), mitosis ≥ 1/mm2 (H&E, p: 0.000; CD34/SOX10, p: 0.004), pT (H&E, p: 0.000; CD34/SOX10, p: 0.001), Breslow thickness (H&E, p: 0.000; CD34/SOX10, p: 0.001), and lymph node and/or distant metastasis (H&E, p: 0.005; CD34/SOX10, p: 0.000); only H&E was associated with ulceration (p: 0.002) and distant metastasis (p: 0.000), conversely, only CD34/SOX10 was associated with lymph node metastasis (p: 0.003).

CONCLUSIONS

CD34/SOX10 does not improve the IrOA and the IaOA of the LVI assessment in CM; furthermore, H&E and CD34/SOX10 show a similar profile of association with the other unfavorable clinical-pathological features of CM. As result, CD34/SOX10 could be a redundant diagnostic tool if applied for the prognostic characterization of not-selected CM in a routine diagnostic scenario.

Three Types of Nodal Melanocytic Nevi in Sentinel Lymph Nodes of Patients With Melanoma: Pitfalls, Immunohistochemistry, and a Review of the Literature

The presence or absence of metastasis in sentinel lymph nodes often drives melanoma staging, prognosis, and treatment. However, distinguishing between metastatic melanoma cells and clusters of benign melanocytic nevus cells is not always straightforward. When morphologic hematoxylin and eosin interpretation alone is not sufficient, additional hematoxylin and eosin sections and immunohistochemical (IHC) studies may be beneficial. This review and small cases series of 3 diagnostically challenging melanocytic sentinel lymph node cases highlights the IHC approach to evaluate intraparenchymal nodal melanocytic nevi, coexistent metastatic melanoma with adjacent melanocytic nevi cells, and nodal blue nevi. In challenging cases, cytological morphology of the melanocytes, location within the lymph node, and IHC studies may assist in diagnosis. If these tools yield conflicting results, expert opinion is recommended.

CD63 expression in metastatic melanoma and melanocytic nevi in lymph nodes

Lymph node status remains one of the most important determinants for prognosis in patients with invasive malignant melanoma. Immunohistochemical stains are routinely employed in the histopathologic evaluation of sentinel lymph nodes removed for staging in patients with melanoma. Histologic analysis may reveal the presence of incidental benign melanocytic nevus cell inclusions (BMNCI), which are critical to distinguish from metastatic melanoma (MM). Our study assesses the utility of NK1 C3 (CD63) immunohistochemical staining in distinguishing between MM and BMNCI in sentinel lymph nodes. We found no difference in staining of MM and BMNCI, precluding its usefulness in differentiating between benign and malignant melanocytes. Thus CD63 lacks specificity when facing challenging cases requiring distinction between benign and malignant melanocytic cells; however, in combination with other immunohistochemical antibodies, CD63 may be useful in supporting melanocytic differentiation. Distinguishing MM and BMNCI continues to be a diagnostic challenge at times. Further research is needed to identify potentially useful markers to provide better diagnostic utility when evaluating lymph node biopsies in patients with melanoma.

Challenges in sentinel node pathology in the era of adjuvant treatment

BACKGROUND

With the approval of adjuvant therapy for stage III melanoma, accurate staging is more important than ever. Sentinel node biopsy (SNB) is an accurate staging tool, yet the presence of capsular nevi (CN) can lead to a false-positive diagnosis.

PATIENTS AND METHODS

Retrospective analysis of the American Joint Committee on Cancer 7th edition stage IIIA melanoma patients who were treated at our institute between 2000 and 2015. SNB slides were reviewed for this study by an expert melanoma pathologist.

RESULTS

Of 159 eligible patients, 14 originally diagnosed with metastatic melanoma merely had CN (8.8%). Another two merely had melanophages (1.3%). Thus, 10.1% of SNs were considered false positive after revision. In 12 patients, the SN tumor burden was originally reported as larger than 1 mm but turned out to be less than 1 mm. Four patients originally reported as SN tumor burden less than 1 mm before revision turned out to have larger than 1 mm. These patients might have been over- or undertreated in the current era of adjuvant therapy for stage III melanoma.

CONCLUSIONS

Distinguishing metastatic melanoma from benign CN and melanophages can be a diagnostic challenge. We plead for an expert pathologists' review, especially when using the SNB + results to determine treatment consequences.

Correlation of Tumor Burden in Sentinel Lymph Nodes with Tumor Burden in Nonsentinel Lymph Nodes and Survival in Cutaneous Melanoma

PURPOSE

In patients with cutaneous melanoma, metastasis in a nonsentinel lymph node (non-SLN) is a strong independent adverse prognostic factor. However, patients with a tumor-involved SLN no longer routinely undergo completion lymph node dissection (CLND). We hypothesized that SLN tumor burden may predict non-SLN tumor burden.

EXPERIMENTAL DESIGN

We compared tumor burden parameters between SLN and non-SLN in patients with cutaneous melanoma who underwent SLN biopsy with a positive SLN during 2003 to 2008 at The University of Texas MD Anderson Cancer Center.

RESULTS

We identified 336 eligible patients with a positive SLN. Of these, 308 (92%) underwent CLND, and 35 (10%) had non-SLN metastasis. The median follow-up time was 6.0 years. For patients with maximum diameter of tumor in the SLN ≤2.0 mm, >2.0-5.0 mm, and >5.0 mm, non-SLN metastasis was detected in 5 of 200 patients (3%), 10 of 63 patients (16%), and 20 of 57 patients (35%), and the mean maximum diameters of the non-SLN tumor deposits were 0.09, 1.56, and 2.71 mm, respectively (P < 0.0001). The percentage of patients with both subcapsular and intraparenchymal non-SLN tumor was higher for patients with SLN tumor in both locations than for patients with SLN tumor in only one location (P < 0.0001). Extranodal extension in a non-SLN was more common in patients with extranodal extension in an SLN (P = 0.003).

CONCLUSIONS

In patients with cutaneous melanoma who undergo CLND, SLN tumor burden predicts non-SLN tumor burden. SLN tumor burden parameters provide accurate prognostic stratification independent of non-SLN status and should be considered for incorporation into future staging systems and integrated risk models.

Utility of Multistep Protocols in the Analysis of Sentinel Lymph Nodes in Cutaneous Melanoma: An Assessment of 194 Cases

Context.—

Currently, no universal protocol exists for the assessment of sentinel lymph nodes (SLNs) in cutaneous melanoma. Many institutions use a multistep approach with multiple hematoxylin-eosin (H&E) and immunohistochemical stains. However, this can be a costly and time- and resource-consuming task.

Objective.—

To assess the utility for multistep protocols in the analysis of melanoma SLNs by specifically evaluating the Calgary Laboratory Services (CLS) protocol (which consists of 3 H&E slides and 1 S100 protein, 1 HMB-45, and 1 Melan-A slide per melanoma SLN block) and to develop a more streamlined protocol.

Design.—

Histologic slides from SLN resections from 194 patients with diagnosed cutaneous melanoma were submitted to the CLS dermatopathology group. Tissue blocks were processed according to the CLS SLN protocol. The slides were re-reviewed to determine whether or not metastatic melanoma was identified microscopically at each step of the protocol. Using SPSS software, a decision tree was then created to determine which step most accurately reflected the true diagnosis.

Results.—

We found with Melan-A immunostain that 337 of 337 negative SLNs (100%) were correctly diagnosed as negative and 55 of 56 positive nodes (98.2%) were correctly diagnosed as positive. With the addition of an H&E level, 393 of 393 SLNs (100%) were accurately diagnosed.

Conclusions.—

We recommend routine melanoma SLN evaluation protocols be limited to 2 slides: 1 H&E stain and 1 Melan-A stain. This protocol is both time- and cost-efficient and yields high diagnostic accuracy.

Update on eighth edition American Joint Committee on Cancer classification for Merkel cell carcinoma and histopathological parameters that determine prognosis

Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine carcinoma. The annual incidence of MCC is increasing in the USA. Timely diagnosis and proper staging of this tumour are crucial as MCC has high rates of regional recurrence and lymph node and distant metastasis. In this review, we outline the key differences between the tumor node metastasis (TNM) staging criteria for MCC in the seventh and eighth editions of the AJCC Cancer Staging Manual We also discuss histopathological parameters that are not included in the eighth edition of the manual but have been shown in other studies to predict a worse prognosis in patients with MCC. Correct assessment and reporting of these clinically relevant histopathological parameters is of utmost importance for practising pathologists as management differs according to the stage of the tumour. This review aims to increase awareness of all these parameters, and proper recognition would guide the treating clinicians towards the most appropriate treatment options that can be given to patients.

A unique gene expression signature is significantly differentially expressed in tumor-positive or tumor-negative sentinel lymph nodes in patients with melanoma

The purpose of this study was to learn whether molecular characterization through gene expression profiling of node-positive and node-negative sentinel lymph nodes (SLNs) in patients with clinical stage I and II melanoma may improve the understanding of mechanisms of metastasis and identify gene signatures for SLNs/SLNs that correlate with diagnosis or clinical outcome. Gene expression profiling was performed on SLN biopsies of 48 (24 SLN and 24 SLN) patients (T3a/b-T4a/b) who underwent staging of SLNs using transcriptome profiling analysis on 5 μm sections of fresh SLNs. U133A 2.0 Affymetrix gene chips were used. Significance analysis of microarrays was used to test the association between gene expression level and SLN status. Genes with fold change more than 1.5 and q value less than 0.05 were considered differentially expressed. Pathway analysis was performed using Ingenuity Pathway Analysis. The Benjamini and Hochberg method was used to adjust for multiple testing in pathway analysis. We identified 89 probe sets that were significantly differentially expressed (1.5-27-fold; q<0.05). Upon performing the pathway analysis, it was found that 25 genes were common among the most significant and biologically relevant canonical pathways. The molecules and pathways that achieved differential expression of highest statistical significance were notably related to melanoma and its microenvironment and to signaling pathways implicated in immunosuppression and development of cancer. A 25-gene signature is significantly differentially expressed between SLN and SLN and is related to melanoma oncogenesis and immunosuppression. The identified expression profile provides a signature of melanoma nodal involvement. These findings warrant further investigation into the mechanisms of metastasis, melanoma metastasis diagnosis, and prediction of outcome.

Clinical impact of ulceration width, lymphovascular invasion, microscopic satellitosis, perineural invasion, and mitotic rate in patients undergoing sentinel lymph node biopsy for cutaneous melanoma: a retrospective observational study at a comprehensive cancer center

The prognostic significance of the width of the ulceration in primary melanomas remains unclear, and there is a relative paucity of data for lymphovascular invasion (LVI), microscopic satellitosis (MS), perineural invasion (PNI), and mitotic rate when compared with other pathological elements currently required for reporting. To evaluate the prognostic importance of the ulceration width and other important pathologic measurements, a single-institutional retrospective study was conducted using records of cutaneous melanoma patients who underwent sentinel lymph node (SLN) biopsy at The University of Texas, MD Anderson Cancer Center between 2003 and 2008. We identified 1898 eligible patients with median tumor thickness of 1.25 mm and median follow-up of 6.7 years. By multivariable analyses, the strongest risk factor for SLN positivity was high tumor thickness followed by the presence of LVI. The pathologic measures with the strongest influence on recurrence-free survival (RFS) were tumor thickness and positive SLN status. Ulceration width and presence of MS were also significantly associated with RFS while PNI was not. Factors with the strongest influence on melanoma-specific survival (MSS) were positive SLN status and mitotic rate. In conclusion, SLN biopsy should probably be offered if the primary tumor has LVI. MS is an adverse prognostic factor for RFS, but its influence on outcome is modest. Ulceration width predicts RFS but loses its independent prognostic significance for MSS when adjusting for currently used clinicopathological factors. In view of its impact on MSS, mitotic rate should be recorded for cutaneous invasive melanomas across all T categories.

Agreement Between Cytology and Histopathology for Regional Lymph Node Metastasis in Dogs With Melanocytic Neoplasms

Melanocytic neoplasms are common in dogs and frequently occur within the oral cavity or in haired skin. The behavior of melanocytic neoplasms is variable and depends on tumor location, size, and histopathologic features. This study compared cytopathology and histopathology of 32 lymph nodes from 27 dogs diagnosed with melanocytic neoplasms. Agreement between the original cytology report, cytology slide review, original histopathology report, and histopathology slide review was determined for each lymph node. A subset of lymph nodes was subjected to immunohistochemistry (Melan-A) and additional histochemical stains/techniques (Prussian blue, bleach) to assist in differentiation of melanocytes and melanophages. Agreement ranged from slight to fair for each of the variables evaluated with weighted kappa (κw) or kappa (κ) analysis (original cytology vs cytology review κw = 0.24; original cytology vs original histopathology κw = 0.007; original cytology vs histopathology review κw = 0.23; cytology review vs original histopathology κw = 0.008; cytology review vs histopathology review κw = 0.006; and original histopathology vs histopathology review κ = 0.18). The diagnoses (metastatic, equivocal, or negative for metastasis) of the original report and slide review for both cytology and histopathology were not significantly correlated with survival in this population of patients. Overall, agreement between cytology and histopathology was poor even with a single clinical or anatomic pathologist performing slide review. Consensus between routine cytology and histopathology for staging of lymph nodes in patients with melanocytic neoplasms is poor and does not correlate with survival.

EANM practice guidelines for lymphoscintigraphy and sentinel lymph node biopsy in melanoma

PURPOSE

Sentinel lymph node biopsy is an essential staging tool in patients with clinically localized melanoma. The harvesting of a sentinel lymph node entails a sequence of procedures with participation of specialists in nuclear medicine, radiology, surgery and pathology. The aim of this document is to provide guidelines for nuclear medicine physicians performing lymphoscintigraphy for sentinel lymph node detection in patients with melanoma.

METHODS

These practice guidelines were written and have been approved by the European Association of Nuclear Medicine (EANM) to promote high-quality lymphoscintigraphy. The final result has been discussed by distinguished experts from the EANM Oncology Committee, national nuclear medicine societies, the European Society of Surgical Oncology (ESSO) and the European Association for Research and Treatment of Cancer (EORTC) melanoma group. The document has been endorsed by the Society of Nuclear Medicine and Molecular Imaging (SNMMI).

CONCLUSION

The present practice guidelines will help nuclear medicine practitioners play their essential role in providing high-quality lymphatic mapping for the care of melanoma patients.

Cutaneous malignancy of the head and neck

Most skin cancers of the head and neck are nonmelanoma skin cancers (NMSCs). Basal cell carcinoma and squamous cell carcinoma are the most frequent types of NMSCs. Treatment options including wide local excision, Mohs surgery, sentinel lymph node biopsy, and cervical lymphadenectomy and adjuvant radiation when warranted offer a high cure rate, while balancing excellent functional and cosmetic outcomes. Evaluation by a multidisciplinary team is highly recommended with advanced and aggressive lesions. Avoidance of sunburns and acute sun damage, sunscreen protection, and early identification and evaluation of suspicious lesions remain the first line of defense against skin cancers.

Lack of standards for the detection of melanoma in sentinel lymph nodes: a survey and recommendations

CONTEXT

Detection of microscopic melanoma metastases in sentinel lymph nodes drives clinical care; patients without metastases are observed, and patients with metastases are offered completion lymphadenectomy and adjuvant therapy.

OBJECTIVE

We sought to determine common elements in currently used analytic platforms for sentinel lymph nodes in melanoma patients.

DESIGN

An electronic survey was distributed to 83 cancer centers in North America.

RESULTS

Seventeen responses (20%) were received. The number of sentinel lymph node mapping procedures for melanoma ranged from less than 11 to more than 100 patients per year, with 72% of institutions mapping more than 50 melanoma patients a year. Uniform practices included (1) processing all of the lymph node tissue rather than submitting representative sections and (2) use of immunohistochemical stains if no tumor was identified on the hematoxylin-eosin-stained sections. Significant variability existed regarding the method of sectioning lymph nodes at grossing and in the histology laboratory; most bisected nodes longitudinally (94%) and performed deeper levels into the block (67%), but these were not uniform practices. S-100 was the most commonly used immunohistochemical stain (78%), followed by Melan-A (56%), MART-1 (50%), HMB-45 (44%), tyrosinase (33%), MiTF (11%), and pan-melanoma (6%).

CONCLUSIONS

There is a need for a standardized platform for detecting melanoma in sentinel lymph nodes. Current practices by a majority of laboratories and findings in the reported literature support the following: histologic evaluation of all lymph node tissue, use of immunohistochemical stains, bisecting lymph nodes longitudinally, and performing deeper levels into the tissue block.

Impact of the 2009 (7th edition) AJCC melanoma staging system in the classification of thin cutaneous melanomas

CONTEXT

The 7th (2009) edition of the AJCC melanoma staging system incorporates tumor (Breslow) thickness, MR, and ulceration in stratifying T1 primary melanomas. Compared to the prior 6th (2001) edition, MR has replaced CL for thin melanomas.

OBJECTIVE

We sought to identify and report differences of the classification of thin melanomas as well as outcome of SLNB in patients according to the 6th and 7th editions at our institution.

RESULTS

106 patients were identified with thin melanomas verified by wide excision. 31 of 106 thin melanomas were reclassified according to the 7th edition of the AJCC. Of those 31, 15 CL II/III patients (6th edition T1a) were reclassified as T1b based on the presence of mitoses while 16 CL IV patients (6th edition T1b) were categorized as T1a based on the absence of mitoses. 26/31 reclassified patients underwent SLNB, and all were negative. Patients with thin melanoma and a +SLNB (N = 3) were all classified as T1b according to both staging systems.

CONCLUSIONS

In our experience, 29% of thin melanomas were reclassified according to the 7th edition with similar proportions of patients re-distributed as T1a (14%) and T1b (15%). Cases with +SLN corresponded with T1b lesions in both 6th and 7th editions.

Controversial issues on melanoma

In this chapter, we try to debate two of the most several controversial points about melanoma: the role of the ultraviolet (UV) ray exposure and the position of the sentinel node biopsy in the dermatological daily activity. It has been demonstrated as a direct relationship between UV exposure and the risk of developing melanoma, but it is also true that a chronic continuous UV ray exposure can develop a protective action. Nodal evaluation is one of the most important prognostic indicators to be considered for the patient outcome. The aims for which sentinel node biopsy is so often adopted can be summarized in three points: a detailed nodal staging, a regional disease control, and a possible overall improved survival. At present, many authors do not think that it let the overall survival grow; therefore, they suggest its use only to stage regional lymph nodes and accurately identify patients who could benefit through an early complete regional lymphadenectomy.

Cutaneous melanocytic lesions: do not miss the invisible gorilla

Of all pathology fields, the analysis of melanocytic lesions has one of the highest rates of review for legal reasons, particularly regarding the distinction between nevus and melanoma. Among the most frequently involved are desmoplastic melanoma, nevoid melanoma, and Spitz nevus versus spitzoid melanoma. Therefore, it follows that pathologists and dermatopathologists should pay special attention when dealing with such type of lesions. This review article will emphasize a number of clinical, histologic, and immunohistochemical features we believe are essential when evaluating lesions whose differential diagnosis includes melanoma/nevus. Furthermore, we want to stress the importance of examining the entire slide within the context of all available information in order to not miss the invisible gorilla in the slide. Regarding this apparently bizarre choice to illustrate these problems (to not miss an invisible gorilla), we request the reader to continue reading this article to find out why.