Sentinel lymph node biopsy as an adjunct to management of histologically difficult to diagnose melanocytic lesions: a proposal

Diagnostic Algorithm to Subclassify Atypical Spitzoid Tumors in Low and High Risk According to Their Methylation Status

Current diagnostic algorithms are insufficient for the optimal clinical and therapeutic management of cutaneous spitzoid tumors, particularly atypical spitzoid tumors (AST). Therefore, it is crucial to identify new markers that allow for reliable and reproducible diagnostic assessment and can also be used as a predictive tool to anticipate the individual malignant potential of each patient, leading to tailored individual therapy. Using Reduced Representation Bisulfite Sequencing (RRBS), we studied genome-wide methylation profiles of a series of Spitz nevi (SN), spitzoid melanoma (SM), and AST. We established a diagnostic algorithm based on the methylation status of seven cg sites located in TETK4P2 (Tektin 4 Pseudogene 2), MYO1D (Myosin ID), and PMF1-BGLAP (PMF1-BGLAP Readthrough), which allows the distinction between SN and SM but is also capable of subclassifying AST according to their similarity to the methylation levels of Spitz nevi or spitzoid melanoma. Thus, our epigenetic algorithm can predict the risk level of AST and predict its potential clinical outcomes.

Comprehensive Clinical, Histopathologic, and Molecular Analysis and Long-term Follow-up of Patients With Nodal Blue Nevi

Blue nevi are benign, melanocytic neoplasms that show a range of clinical and morphologic patterns and include common/dendritic, cellular, and atypical cellular subtypes. Like other nevi, they most commonly occur in skin but can occasionally involve lymph nodes where they may be misinterpreted as representing metastatic melanoma. Moreover, whether benign blue nevi can metastasize to lymph nodes and their natural history and prognostic significance has been the subject of great controversy. To date, few cases of nodal blue nevi have been reported in the literature, and those reports have had limited clinical follow-up and supporting molecular data. This study sought to determine the clinical, pathologic, and molecular features of blue nevi involving lymph nodes, clarify their clinical significance, provide evidence for understanding their pathogenesis, and highlight potential pitfalls in the interpretation of lymph nodes with an ultimate aim of improving patient care. Thirteen cases of blue nevi involving lymph nodes were identified in the archives of Royal Prince Alfred Hospital, Sydney, Australia (1984-2018). A detailed assessment of the clinical and pathologic features of each case was performed, including an evaluation of all available immunohistochemical stains. Extended clinical follow-up was available for 9 patients. Droplet digital polymerase chain reaction for GNAQ Q209L, Q209P and GNA11 Q209L mutations was performed on 7 cases of blue nevi within lymph nodes together with matching cutaneous (presumed primary) blue nevi in 2 cases. All cases showed typical histologic features of blue nevi. BAP1 was retained in all cases (n=7). There were no recurrence or metastasis of blue nevus in any case on long-term clinical follow-up (n=9, median follow-up, 12 y). The majority of cases (n=5 of 7 evaluated) had GNAQ and GNA11 driver mutations. The 2 patients with a matched primary cutaneous blue nevus and regionally associated nodal blue nevus had the same GNAQ Q209L mutation in both sites in each patient. We conclude that blue nevi can involve lymph nodes and are associated with benign clinical behavior, and probably represent so-called "benign" metastasis. Awareness of these lesions is important when evaluating lymph nodes to avoid misdiagnosis as metastatic melanoma.

A sixteen-year single-center retrospective chart review of Spitz nevi and spitzoid neoplasms in pediatric patients

BACKGROUND

Spitzoid neoplasms in pediatric patients pose an interesting challenge for clinicians. More data on the clinical, histologic, and molecular characteristics of these lesions are necessary to distinguish features that may portend recurrence or malignant behavior to help determine future treatment guidelines in pediatric patients.

METHODS

Institutional Review Board approval was obtained from Children's Hospital of Wisconsin to conduct a retrospective analysis of spitzoid neoplasms. Patients with biopsied or excised spitzoid neoplasms between 01/01/2000 and 08/01/2016 were included. Pertinent clinical and histologic data were collected. Atypical, unusual, or diagnostically uncertain lesions were selected for re-review.

RESULTS

266 lesions from 264 patients were included. 243 were classified as benign (91.35%), 22 as atypical (8.27%), and 1 as spitzoid melanoma (0.38%). No clinical or histologic variables were found to be statistically significant between the benign Spitz, atypical Spitz, and spitzoid melanoma cohorts. No known deaths occurred.

CONCLUSION

Our findings highlight the extreme variability of spitzoid neoplasms clinically and histologically. Importantly, this study demonstrates that the vast majority of spitzoid neoplasms in pediatric populations are benign and supports conservative management of spitzoid lesions in children.

Spitz Nevus and Other Spitzoid Tumors in Children. Part 2: Cytogenetic and Molecular Features. Prognosis and Treatment

Melanocytic neoplasms with spitzoid morphology (Spitz nevi, atypical Spitz tumors, and spitzoid melanomas) may be benign or malignant. Because the malignant potential of atypical Spitz tumors is uncertain, the proper therapeutic approach has been much debated over the years. Promising new techniques for molecular analysis have enabled better predictions of the biological behavior of these tumors. We review their cytogenetic features and prognosis and also provide an update of the most recent recommendations for management.

A Practical Approach to the Diagnosis of Melanocytic Lesions

CONTEXT.—

Melanocytic lesions are common in routine surgical pathology. Although the majority of these lesions can be confidently diagnosed using well-established morphologic criteria, there is a significant subset of lesions that can be diagnostically difficult. These can be a source of anxiety for patients, clinicians, and pathologists, and the potential consequences of a missed diagnosis of melanoma are serious.

OBJECTIVE.—

To provide a practical approach to the diagnosis of melanocytic lesions, including classic problem areas as well as suggestions for common challenges and appropriate incorporation of ancillary molecular techniques.

DATA SOURCES.—

Literature search using PubMed and Google Scholar, incorporating numerous search terms relevant to the particular section, combined with contemporaneous texts and lessons from personal experience.

CONCLUSIONS.—

Although a subset of melanocytic lesions can be diagnostically challenging, the combination of a methodical approach to histologic assessment, knowledge of potential diagnostic pitfalls, opinions from trusted colleagues, and judicious use of ancillary techniques can help the pathologist navigate this difficult area.

Sentinel Node Biopsy in Melanoma: A Short Update

Several controversies are still ongoing about sentinel node biopsy in melanoma. It is basically a staging procedure for melanoma > 0.75 mm in thickness or for thinner melanoma in the presence of ulceration, high mitotic rate, and/or lymphovascular invasion. Complete lymph node dissection after a positive sentinel node can also allow a better locoregional disease control but seems not to prevent the development of distant metastases. The use of sentinel node biopsy in atypical Spitz tumors should be discouraged because of their peculiar biological properties.

Update on dermoscopy of Spitz/Reed naevi and management guidelines by the International Dermoscopy Society

Spitzoid lesions represent a challenging and controversial group of tumours, in terms of clinical recognition, biological behaviour and management strategies. Although Spitz naevi are considered benign tumours, their clinical and dermoscopic morphological overlap with spitzoid melanoma renders the management of spitzoid lesions particularly difficult. The controversy deepens because of the existence of tumours that cannot be safely histopathologically diagnosed as naevi or melanomas (atypical Spitz tumours). The dual objective of the present study was to provide an updated classification on dermoscopy of Spitz naevi, and management recommendations of spitzoid-looking lesions based on a consensus among experts in the field. After a detailed search of the literature for eligible studies, a data synthesis was performed from 15 studies on dermoscopy of Spitz naevi. Dermoscopically, Spitz naevi are typified by three main patterns: starburst pattern (51%), a pattern of regularly distributed dotted vessels (19%) and globular pattern with reticular depigmentation (17%). A consensus-based algorithm for the management of spitzoid lesions is proposed. According to it, dermoscopically asymmetric lesions with spitzoid features (both flat/raised and nodular) should be excised to rule out melanoma. Dermoscopically symmetric spitzoid nodules should also be excised or closely monitored, irrespective of age, to rule out atypical Spitz tumours. Dermoscopically symmetric, flat spitzoid lesions should be managed according to the age of the patient. Finally, the histopathological diagnosis of atypical Spitz tumour should warrant wide excision but not a sentinel lymph-node biopsy.

Pediatric melanoma

Childhood melanoma is a rare pediatric malignancy, with fewer than 500 new diagnoses annually. The incidence is increasing, particularly in the adolescent population. This review highlights the epidemiology, clinical presentation, and histopathologic challenges of pediatric melanoma. Surgical resection remains the cornerstone for localized and regionally advanced disease. Adjuvant therapies, including current options and potential novel therapeutics for this unique population will be discussed.

The complex management of atypical Spitz tumours

In recent years, advances in molecular genetic characterisation have revealed that atypical Spitz tumours (ASTs) are basically heterogeneous diseases, although the clinical relevance of these findings is yet to be determined. Evidence of molecularly-defined diverse groups of lesions continues to accumulate; however, conflicting, confusing, and overlapping terminology has fostered ambiguity and lack of clarity in the field in general. The lack of fundamental diagnostic (morphological) unambiguous classification framework results in a number of challenges in the interpretation of the molecular genetic data. In this review, we discuss the main difficulties for pathologists and clinicians in the complex management of ASTs, with particular emphasis on the different genetic and biological features of recently-described entities, and offer our view of what could be medically reasonable to guide a rational approach in light of current data.

Atypical Spitzoid neoplasms: a review of potential markers of biological behavior including sentinel node biopsy

Atypical cutaneous melanocytic lesions, including those with Spitzoid features, can be difficult to categorize as benign or malignant. This can lead to suboptimal management, with potential adverse patient outcomes. Recent studies have enhanced knowledge of the molecular and genetic biology of these lesions and, combined with clinicopathological findings, is further defining their biological spectrum, classification, and behavior. Sentinel node biopsy provides important prognostic information in patients with cutaneous melanoma, but its role in the management of melanocytic lesions of uncertain malignant potential (MELTUMP) is controversial. This paper examines the role of molecular testing and sentinel node biopsy in MELTUMPs, particularly atypical Spitzoid tumors.

Atypical Spitz tumours and sentinel lymph node biopsy: a systematic review

Sentinel lymph node biopsy has been proposed as a diagnostic method for estimation of the malignant potential of atypical Spitz tumours. However, although cell deposits are commonly detected in the sentinel lymph nodes of patients with atypical Spitz tumours, their prognosis is substantially better than that of patients with melanoma and positive sentinel lymph node biopsies. We did a systematic review of published reports to assess the role of sentinel lymph node biopsy as a prognostic method in the management of atypical Spitz tumours. The results of our analysis did not show any prognostic benefit of sentinel lymph node biopsy; having a positive sentinel lymph node does not seem to predict a poorer outcome for patients with atypical Spitz tumours. These findings indicate that, especially in the paediatric population, it might be prudent initially to use complete excision with clear margins and careful clinical follow-up in patients with atypical Spitz tumours.

Clear cell nodular hidradenoma involving the lymphatic system: a tumor of uncertain malignant potential or a novel example of "metastasizing" benign tumor?

Exceedingly rare cases of neoplasms with clear-cut histopathologic features of benignity can show locoregional or even distant spread. Such cases can become putative examples of "benign metastasis" when a completely favorable clinical outcome is documented after an adequately long follow-up. We report 8 cases of morphologically benign clear cell nodular hidradenoma (CCNH) with lymphatic involvement. In 5 cases the cutaneous tumor showed small foci of intravascular deposits of neoplastic cells; in 2 cases the cutaneous tumor presented with a synchronous tumor in a regional node; in 1 case a nodal location CCNH was found with no evidence of any primary in the skin. All the cases were treated with conservative surgery and none of them showed disease progression during a follow-up period ranging from 2 to 11 years. These data suggest that in the absence of other histopathologic features of malignancy, lymphatic spread in CCNH can still carry an excellent prognosis and can be therefore considered as an example of "benign metastasis." As the latter concept can be set forth only after an uneventful long-term follow-up, in routine practice, cases of morphologically benign CCNH with lymphatic involvement are best labeled "atypical CCNH," or "CCNH-like tumor of uncertain malignant potential."

Sentinel node biopsy in atypical melanocytic neoplasms in childhood: a single institution experience in 24 patients

INTRODUCTION

Sentinel lymph node biopsy (SLNB) is a controversial but frequently used adjunct to wide excision of difficult-to-diagnose melanocytic proliferations of childhood. We herein report our institutional experience with SLNB in pediatric patients with these lesions, hereafter referred to as 'atypical melanocytic proliferations'.

METHODS

Our prospectively collected melanoma database was queried for patients ≤21 years of age status post-SLNB for a diagnosis of atypical melanocytic proliferation in which the diagnosis of melanoma ≥1 mm in depth was considered in the differential diagnosis by one or more expert dermatopathologists and for which no diagnostic consensus could be reached.

RESULTS

Of 24 patients identified over 17 years, 7 patients (29%) had a positive sentinel lymph node (SLN). Six SLN-positive patients underwent complete lymph node dissection, with one (14%) having additional nodal involvement identified. With a median follow-up of 4.1 years (range < 0.1 to 14.8 years), all patients showed no evidence of disease.

CONCLUSIONS

Despite a significant rate of identification of melanocytes in SLNs of children with atypical melanocytic proliferations, survival appears favorable and controversy surrounding the significance of nodal involvement remains. Further studies with larger numbers of patients and long-term follow-up are needed before the true prognostic value of SLNB in this setting can be determined.

Spitz nevi and other Spitzoid lesions part II. Natural history and management

For dermatologists, evidence-based management guidelines for Spitz tumors have not been established. Despite the lack of a standardized approach, most dermatologists recommend the excision of Spitz tumors occurring in adults and adopt more conservative measures towards pediatric cases. The histopathologic attributes and the clinical scenario are factored into management in each case. While the metastatic behavior of certain Spitz tumors is well known, the malignant potential of these lesions remains unclear because they only rarely result in negative outcomes. The risks and benefits of adjunctive measures, such as sentinel lymph node biopsy and interferon use, remain untested and are subjects of ongoing controversy. (In part II of this continuing medical education article, we will continue to use the terminology defined in part I for purposes of continuity. "Spitz tumor" is used as the umbrella term for the entire category of lesions, "common Spitz nevi" refers to only the most typical lesions seen in pediatric cases, and "atypical Spitz tumors" encompass the "all other" category, which continues to cause debate.).

Atypical Spitzoid melanocytic tumors: a morphological, mutational, and FISH analysis

BACKGROUND

Identification of the clinical behavior of atypical Spitzoid tumors with conflicting histopathologic features remains controversial.

OBJECTIVE

We sought to assess whether molecular findings may be helpful in the diagnostic and prognostic assessment of atypical Spitzoid tumors.

METHODS

A total of 38 controversial, atypical Spitzoid lesions (≥ 1 mm in thickness) were analyzed for clinicopathological features, chromosomal alterations by fluorescence in situ hybridization (FISH) analysis (RREB1/MYB/CCND1/CEP6), BRAF(V600E) mutation by allele-specific real-time polymerase chain reaction confirmed by sequencing, and H-RAS gene mutation by direct sequencing.

RESULTS

Atypical Spitzoid lesions developed in 21 female and 17 male patients (mean age 22 years). Nine patients underwent sentinel lymph node biopsy and a sentinel lymph node micrometastasis was detected in 4 of these 9 cases. Four additional patients, who did not receive a sentinel lymph node biopsy, experienced bulky lymph node metastases and one experienced visceral metastases and death. Lesions from patients with lymph node involvement showed more deep mitoses (P < .01), less inflammation (P = .05), and more plasma cells (P = .04). FISH analysis demonstrated the presence of chromosomal alterations in 6 of 25 cases. Correlation with follow-up data showed that the only case with fatal outcome showed multiple chromosomal alterations by FISH analysis. BRAF(V600E) mutation was detected in 12 of 16 cases (75%) and H-RAS mutation on exon 3 was found in 3 of 11 cases (27%).

LIMITATIONS

Our results require validation in a larger series with longer follow-up information.

CONCLUSIONS

FISH assay may be of help in the prognostic evaluation of atypical Spitzoid tumors. Diagnostic significance of BRAF(V600E) and H-RAS mutations in this setting remains unclear.

Melanoma and melanocytic tumors of uncertain malignant potential in children, adolescents and young adults--the Stanford experience 1995-2008

Pediatric melanoma is difficult to study because of its rarity, possible biological differences in preadolescents compared with adolescents, and challenges of differentiating true melanoma from atypical spitzoid neoplasms. Indeterminant lesions are sometimes designated as melanocytic tumors of uncertain malignant potential (MelTUMPs). We performed a retrospective, single-institution review of melanomas, MelTUMPs and Spitz nevi with atypical features (SNAFs) in patients at 21 years of age and younger from 1995 to 2008. We identified 13 patients with melanoma, seven with MelTUMPs, and five with SNAFs. The median age for melanoma patients was 17 years, 10 for MelTUMPs, and six for SNAFs. Of the 13 melanoma patients, only four were younger than 15 years, while six were adolescents, and three were young adults. Nine melanoma patients (69%) were female. The most common histologic subtype was superficial spreading. The median depth for melanomas was 1.2 mm, and 3.4 mm for MelTUMPs. Microscopic regional nodal involvement detected on elective or sentinel lymph node (SLN) dissection was present in 2/10 (20%) of primary melanomas and 2/6 (33%) of Mel-TUMPs. Complete lymphadenectomy was performed on four melanoma patients, with three positive cases. Patient outcome through March 31, 2009 revealed no in-transit or visceral metastasis in patients with MelTUMPs or SNAFs. One SLN-positive patient (8%) with melanoma developed recurrent lymph node and liver metastasis and died 15 months after primary diagnosis. Our data highlight the rarity, female predominance, and significant rate of SLN positivity of pediatric melanoma. The high rate of MelTUMPs with regional nodal disease reinforces the need for close follow-up.

Pigmented lesion pathology: what you should expect from your pathologist, and what your pathologist should expect from you

The first part of this review examines the reliability of histologic diagnosis in pigmented lesions, as measured by concordance studies and medicolegal analysis. It emphasizes the role of clinicians in maximizing that reliability, by providing adequate clinical descriptions, using appropriate biopsy technique, and critically interpreting pathology reports. It identifies those entities that are especially problematic, either because they cannot be reliably recognized by the histopathologist or because their histology is a poor guide to their biologic behavior. The second part of the review is a guide to some of the more difficult and controversial pigmented lesions, including dysplastic nevus, spitzoid nevi and melanomas, cellular blue nevus, animal-type melanoma, and deep penetrating nevus.

EANM-EORTC general recommendations for sentinel node diagnostics in melanoma

The accurate diagnosis of a sentinel node in melanoma includes a sequence of procedures from different medical specialities (nuclear medicine, surgery, oncology, and pathology). The items covered are presented in 11 sections and a reference list: (1) definition of a sentinel node, (2) clinical indications, (3) radiopharmaceuticals and activity injected, (4) dosimetry, (5) injection technique, (6) image acquisition and interpretation, (7) report and display, (8) use of dye, (9) gamma probe detection, (10) surgical techniques in sentinel node biopsy, and (11) pathological evaluation of melanoma-draining sentinel lymph nodes. If specific recommendations given cannot be based on evidence from original, scientific studies, referral is given to "general consensus" and similar expressions. The recommendations are designed to assist in the practice of referral to, performance, interpretation and reporting of all steps of the sentinel node procedure in the hope of setting state-of-the-art standards for good-quality evaluation of possible spread to the lymphatic system in intermediate-to-high risk melanoma without clinical signs of dissemination.

Atypical spitzoid melanocytic tumors with positive sentinel lymph nodes in children and teenagers, and comparison with histologically unambiguous and lethal melanomas

Children and teenagers with a positive sentinel lymph node (SLN) after a prior diagnosis of an atypical spitzoid melanocytic tumor (ASMT) are usually cared for clinically in the same way as patients with melanoma. Little is known about long-term follow-up of these individuals to determine whether this practice is appropriate. To learn more about the biology of these tumors we retrospectively reviewed the clinical and pathologic findings of children and teenagers (<18 y of age at the time of diagnosis) with an ASMT, positive SLN and follow-up of at least 3 years. Their findings were compared with histologically unambiguous melanomas of children or teenagers, who had a positive SLN or died of metastatic melanoma. Eleven individuals, 6 girls and 5 boys, with primary ASMT and positive SLN were identified. The primary tumors ranged in thickness from 2.1 to 12 mm (median, 4.6 mm; mean, 5 mm). The tumor mitotic rate ranged from 1 to 10 mitoses/mm (median, 3/mm, median, 3/mm). The positive SLNs included 6 nodes with intranodal melanocytic aggregates measuring <1 mm in greatest dimension, and 5 nodes, in which the size of the melanocyte deposits was >/=1 mm. All the patients with ASMT and positive SLN remained free of disease with a median follow-up of 47 months (mean, 61 mo, range: 36 to 132 mo). In contrast, 2 of 5 patients <18 years of age with a histologically unambiguous melanoma and a positive SLN died of metastatic melanoma. The overall disease-specific mortality rate for all patients <18 years of age diagnosed with melanoma was 12%. Our findings confirm that children and teenagers with ASMTs and positive SLNs have a less aggressive clinical course than those with histologically unambiguous melanoma.

Management of malignant melanoma: best practices

BACKGROUND

Melanoma is a commonly occurring cancer in Canada, with an estimated age-standardized incidence of 10 to 13 per 100,000. An estimated 4,300 new cases were diagnosed, and there were 800 reported deaths in 2005.

OBJECTIVE AND CONCLUSION

The Canadian Expert Panel on Malignant Melanoma has developed best practices to improve the management of malignant melanoma. Sections include recommendations on primary diagnosis, dermatopathologic assessment, and reporting; use of preoperative lymphoscintigraphy and an intraoperative gamma probe to map and biopsy the sentinel lymph node; indications for surgical resection, sentinel node biopsy, and surgery for advance disease; use of interferon-alpha adjuvant therapy and treatment options for stage IV disease; and management of central nervous system metastases.

The atypical Spitz tumor of uncertain biologic potential: a series of 67 patients from a single institution

BACKGROUND

Atypical Spitz tumors (AST) are rare spitzoid melanocytic proliferations with an uncertain malignant potential. ASTs have overlapping features of both Spitz nevi and spitzoid melanoma, and consequently generate controversy with diagnosis and management. Sentinel lymph node biopsy (SLNB) has been proposed as a possible means to gain additional insight into the true biologic potential of these tumors; however, previous reports on the use of SLNB in ASTs have been limited by small numbers of patients and short durations of follow-up.

METHODS

The authors extracted data from their institution's prospective melanoma database, collected between 1994 and 2007, for all patients with ASTs of uncertain biologic potential. They reviewed the clinical features of these patients, including the sentinel lymph node status, and the histological features of the tumors.

RESULTS

A total of 67 patients with ASTs were identified, with a median age of 23.7 years. The mean depth was 2.4 mm. Of these, 57 had a SLNB performed, with 27 (47%) having a positive sentinel lymph node. SLNB-positive cases had a significantly lower mean age than SLNB-negative cases (17.9 vs 28.7 years; P = .013); however, no other significant differences were observed. All 27 patients with a positive SLNB were alive and disease free with median follow-up of 43.8 months. One patient who did not receive a SLNB developed recurrent disease with regional and distant metastases.

CONCLUSIONS

ASTs do not appear to behave like conventional melanoma. There is a high incidence of microscopic lymph node deposits in SLNBs, but despite this finding, patients have a favorable prognosis. Our findings raise several questions regarding the malignant potential of ASTs, and the role of SLNB in their management.

Sentinel lymph node biopsy for patients with diagnostically controversial Spitzoid melanocytic tumors?

The distinction of a Spitz nevus from melanoma can be very difficult. Pathologists may disagree on whether a Spitzoid melanocytic proliferation is benign or malignant, or acknowledge uncertainty about the diagnosis. As long as melanoma is suspected or strongly considered, a clinical management plan is often adopted as if the patient had melanoma, which may include sentinel lymph node (SLN) biopsy for staging. The findings of the sentinel node may resolve the diagnostic controversy about the primary tumor, but there is also the risk for more diagnostic confusion, uncertainty, and errors. We review the arguments in favor and against SLN biopsy for patients with diagnostically controversial Spitzoid melanocytic tumors, summarize current experience, and illustrate diagnostic pitfalls. Although SLN biopsy provides prognostic information helpful for clinical trials, we caution against performing the procedure as a diagnostic adjunct.

Sentinel lymph node biopsy for melanoma: aspects of pathologic assessment

Sentinel lymph node (SLN) biopsy affords an accurate, minimally invasive means of staging and determining prognosis in patients with melanoma and for identifying those patients who may benefit from complete regional lymph node dissection. Careful and accurate histopathologic assessment of SLNs is critical to achieving optimal reliability of the technique. Micromorphometric parameters of melanoma deposits in SLNs have been shown to be predictive of regional non-SLN involvement and of clinical outcomes. Several non-histopathologic methods of SLN evaluation have been investigated, and while some of them show promise for the future, excision and histopathologic examination currently remains the gold standard for the evaluation of SLNs.

Sentinel lymph node biopsy in histologically ambiguous melanocytic tumors with spitzoid features (so-called atypical spitzoid tumors)

BACKGROUND

The distinction of Spitz nevi from melanomas with spitzoid morphology can be difficult. For lesions with overlapping histopathologic features, it may be impossible to predict their malignant potential with certainty. The current study evaluated the role of sentinel lymph node (SLN) biopsy in patients with such atypical spitzoid tumors.

METHODS

The clinical and histopathologic features of 21 patients with atypical spitzoid tumors who underwent SLN biopsy were reviewed and correlated with the presence or absence of metastatic tumor in their corresponding SLNs.

RESULTS

The atypical histopathologic features that were most frequently present included incomplete maturation (11 patients, 52%), two or more dermal mitoses per square millimeter (13 patients, 62%), and deep dermal mitoses (11 patients, 52%). Six patients (29%) showed SLN metastasis. There were histopathologic differences between tumors with positive SLN when compared with tumors with negative SLN: mean tumor thickness (3.38 mm vs. 2.04 mm), incomplete maturation (83% vs. 40%), median dermal mitotic rate (3.5/mm(2) vs. 2/mm(2)), deep dermal mitoses (83% vs. 47%), and expansile dermal nodules (50% vs. 13%). However, of these, only the difference in mean tumor thickness reached statistical significance (P < .05).

CONCLUSIONS

SLN biopsy offers a means of assessing the metastatic potential of atypical spitzoid tumors and aids in the management of these patients by selecting patients who may benefit from a regional node field dissection and those in whom the use of adjuvant therapies could be considered.

[Spitz nevus vs 'spitzoid' malignant melanoma. A diagnostic dilemma?]

Data from the literature and histopathological findings in six personal cases are used to illustrate criteria that can be applied in differential diagnosis between a Spitz nevus and a spitzoid variant of malignant melanoma. The diagnostic term 'atypical Spitz tumor' is explained; it is used to describe a morphological "grey zone" in which it is not possible to differentiate with adequate certainty between a Spitz nevus and a spitzoid malignant melanoma.

The role of sentinel node biopsy in the management of melanocytic lesions of uncertain malignant potential (MUMP)

Melanocytic lesions of uncertain malignant potential (MUMP) is a term which is useful in identifying melanocytic tumours where the distinction between benign and malignant is a histological problem. Sentinel node biopsy is recognised to provide unmatched prognostic information in melanoma patients, but has recently been advocated for diagnostic purposes in MUMP. We present the case of a seven-year-old girl who presented with a six-month history of a changing pigmented lesion on her left upper arm. Excision biopsy not only showed a melanocytic lesion with some spitzoid features but also marked atypia making it appropriate to use the term MUMP. Sentinel node biopsy was undertaken. This case demonstrates that sentinel node biopsy can be performed safely in children. Given the low morbidity of the procedure we advocate that this technique should be considered in this difficult diagnostic situation to further the management of these patients.

Pathological Evaluation of Sentinel Lymph Nodes

The sentinel lymph nodes are the most likely site of nodal metastasis. Their focused analysis results in upstaging cancers, although the extra yield from a more intensive work-up is generally dominated by micrometastases and isolated tumor cells. Nodal staging is generally done to reflect systemic spread of solid tumors and guide treatment accordingly. However, in general, the two processes of haematogenous and lymphogenic spread are not causally interrelated, and the extrapolation from low-volume nodal involvement to systemic involvement and therapeutic consequences of this extrapolation are still under investigation.

Sentinel Lymph Node Biopsy for Atypical Melanocytic Lesions with Spitzoid Features

INTRODUCTION

Sentinel lymph node biopsy (SLNB) is routinely used as a staging procedure for melanomas, however may also assist in understanding the biology of atypical and controversial spitzoid melanocytic skin lesions.

METHODS

Five hundred and forty-nine sentinal lymph node excisions were performed over a 5-year period. Fourteen patients with controversial melanocytic lesions were identified and of these ten underwent SLNB. The histology of the primary skin lesion and corresponding sentinal lymph nodes were evaluated and correlated with outcome.

RESULTS

Thickness of the primary melanocytic lesion ranged from 1.22 to 4 mm. Fifty percent of patients were less than 17 years of age. Ten patients underwent SLNB and three cases (30%) displayed metastatic disease in the SLNB specimen. All three patients were under 17 years of age and all underwent completion axillary dissection. One completion axillary dissection had an additional node with metastasis on routine H&E and immunohistochemical staining. No capsular invasion was seen. All three cases with metastatic disease received adjuvant systemic therapy and remain disease free at 29, 49 and 57 months follow-up. All patients with a negative SLNB remain disease free at mean follow-up of 28.1 months (range: 13-40 months).

CONCLUSION

Our results confirm that some of these spitzoid lesions metastasize to regional lymph nodes and SLNB is a valuable adjunct tool in staging these lesions. However, molecular studies and a prolonged follow-up are needed to determine whether these lesions, especially those occurring in children are comparable to stage matched overt melanoma in adults.

Sentinel lymph node biopsy in patients with “atypical Spitz tumors.” A report on 12 cases

The distinction between Spitz nevus and melanoma is currently possible, applying a set of definite histological criteria. However, in certain lesions deviating from the stereotypical morphology of classic Spitz nevi ("atypical Spitz tumors"), the differentiation between benign and malignant cases appears problematic because objective criteria for a reliable diagnosis are lacking. We report the clinicopathologic findings of 12 patients with atypical Spitz tumors, who underwent sentinel node biopsy. All the tumors, composed of spindle and/or epithelioid cells, histologically showed features referable to Spitz nevi mixed to features generally found in malignant melanomas. Nine patients were females and three males, ranging in age from 2 to 48 years (mean, 23.2 years). The size of lesions ranged from 5 to 9 mm, the thickness from 1.12 to 5.70 mm. Nodal micrometastases were found in 4 (33.3%) patients. Among the patients with positive sentinel node, two showed minimal nodal involvements; one patient showed additional tumor deposits in one nonsentinel regional node. All patients are alive and free of disease with a follow-up of 2 to 90 months (mean, 26.3 months). Metastasizing and nonmetastasizing cases appeared clinically and histologically indistinguishable. The statistical analysis showed no significant difference between the two groups. Results suggested that all the reported cases may constitute a relatively homogeneous morphological group of lesions with a relevant metastatic potential that may be underdiagnosed.

Regressed subungual melanoma simulating cellular blue nevus: managed with sentinel lymph node biopsy

BACKGROUND

Subungual melanoma, a not uncommon presentation of cutaneous melanoma in Asian populations, is easily overlooked as benign and thus is improperly treated.

OBJECTIVE

To present two cases with clinical suspicion of subungual melanoma. Skin biopsies failed to demonstrate the diagnostic features of malignancy.

METHODS

Lymphoscintigraphy and sentinel lymph node (SLN) biopsies were performed to determine regional lymph node status.

RESULTS

Both hematoxylin-eosin and HMB45 staining revealed melanoma cells in the SLN of the patient. The second patient's SLN was negative for malignant cells, but her excised primary lesion showed extensive regressed melanoma.

CONCLUSION

Regression phenomena are not uncommon for subungual melanoma. An extention biopsy techniques are useful for determining nodal basin status in regressed subungual melanoma.