Assessment of the role of sentinel lymph node biopsy for primary cutaneous desmoplastic melanoma

Clinical Characteristics and Special Considerations in the Management of Rare Melanoma Subtypes

Rare histologic subtypes of melanoma, including acral, mucosal, uveal, and desmoplastic melanomas, only make up 5% of all diagnosed melanomas and are often underrepresented in large, randomized trials. Recent advancements in systemic therapy have shown marked improvement in pathologic response rates, improving progression-free and overall survival among cutaneous melanoma patients, but there are limited data to demonstrate improved survival among rarer subtypes of melanoma. Acral melanoma has a poor response to immunotherapy and is associated with worse survival. Mucosal melanoma has a large variability in its presentation, a poor prognosis, and a low mutational burden. Uveal melanoma is associated with a high rate of liver metastasis; recent adoption of infusion and perfusion therapies has demonstrated improved survival among these patients. Desmoplastic melanoma, a high-risk cutaneous melanoma, is associated with high locoregional recurrence rates and mutational burden, suggesting this melanoma may have enhanced response to immunotherapy. While these variants of melanoma represent distinct disease entities, this review highlights the clinicopathologic characteristics and treatment recommendations for each of these rare melanomas and highlights the utility of modern therapies for each of them.

Prognostic and predictive biomarkers in melanoma

Biomarkers help to inform the clinical management of patients with melanoma. For patients with clinically localised primary melanoma, biomarkers can help to predict post-surgical outcome (including via the use of risk prediction tools), better select patients for sentinel lymph node biopsy, and tailor catch-all follow-up protocols to the individual. Systemic drug treatments, including immune checkpoint inhibitor (ICI) therapies and BRAF-targeted therapies, have radically improved the prognosis of metastatic (stage III and IV) cutaneous melanoma patients, and also shown benefit in the earlier setting of stage IIB/C primary melanoma. Unfortunately, a response is far from guaranteed. Here, we review clinically relevant, established, and emerging, prognostic, and predictive pathological biomarkers that refine clinical decision-making in primary and metastatic melanoma patients. Gene expression profile assays and nomograms are emerging tools for prognostication and sentinel lymph node risk prediction in primary melanoma patients. Biomarkers incorporated into clinical practice guidelines include BRAF V600 mutations for the use of targeted therapies in metastatic cutaneous melanoma, and the HLA-A∗02:01 allele for the use of a bispecific fusion protein in metastatic uveal melanoma. Several predictive biomarkers have been proposed for ICI therapies but have not been incorporated into Australian clinical practice guidelines. Further research, validation, and assessment of clinical utility is required before more prognostic and predictive biomarkers are fluidly integrated into routine care.

The utility of SOX10 in mixed type desmoplastic melanoma with lymph node metastasis of the spindle cell component: A cautionary tale of inattentional blindness

Desmoplastic melanoma (DM), a type of spindle cell melanoma separated into pure desmoplastic melanoma (PDM) and mixed desmoplastic melanoma (MDM) subtypes, can be a diagnostic challenge and easily confused for dermal scar, especially PDM. We report a 65-year-old white man who received a left thumb amputation after an initial biopsy for melanoma, an unclassified type with epithelioid morphology. The amputation and sentinel lymph node specimens were significant for residual melanoma with epithelioid morphology, dermal scar, and a slightly expanded "scar-like" capsular area in one of seven lymph nodes, which was diffusely positive for SOX10 on reflex sentinel lymph node immunohistochemical protocol. On re-review of the amputation "scar" like area, a subsequent SOX10 stain confirmed the diagnosis of MDM in this area with epithelioid and spindle cell morphology, significantly upgrading the tumor stage. We share this case to highlight: (i) MDM, although exceptionally uncommon, can result in a pure spindle cell lymph node metastasis, (ii) to encourage increased utilization of SOX10 to assess sentinel lymph node biopsies, especially in the context of melanomas with a spindle cell component, and (iii) share an example of inattentional blindness which was fortunately identified by reflex sentinel lymph node immunohistochemical protocols.

Local Recurrence Rates After Excision of Desmoplastic Melanoma: A Systematic Review and Meta-Analysis

BACKGROUND

Few prospective studies have evaluated local recurrence rates (LRR) after excision of desmoplastic melanoma (DM); however, several retrospective studies have reported high LRR.

OBJECTIVE

To determine LRR after excision of DM and evaluate factors affecting LRR.

MATERIALS AND METHODS

Systematic review of the PubMed, Embase, and Web of Science databases was performed to identify studies reporting local recurrence after excision of DM with conventional wide local excision (WLE), Mohs micrographic surgery (MMS), or staged excision (SE). Meta-analysis was performed to calculate summary LRR and pooled risk ratios (RR).

RESULTS

Literature search identified 4 studies evaluating MMS or SE (total n = 61 DM). 53 studies assessed WLE ( n = 3,080) and were analyzed quantitatively. The overall LRR after WLE of DM was 21% (95% CI, 0.16-0.28; n = 2,308). Local recurrence rate was higher with positive/unknown histologic excision margins (49%, 95% CI, 0.25-0.74; n = 91) versus negative histologic margins (11%, 95% CI, 0.07-0.17; n = 1,075; [ p < .01]). Neurotropism was also associated with increased LRR (RR, 1.79; 95% CI, 1.34-2.38, p < .01; n = 644).

CONCLUSION

DM has high LRR after WLE. Local recurrence risk was greatest with positive excision margins, indicating the importance of achieving negative microscopic margins. Greater study of MMS and SE for DM is required.

Representativeness of initial skin biopsies showing pure desmoplastic melanoma: implications for management

Desmoplastic melanoma (DM) is an uncommon subtype of melanoma with distinct clinicopathological features. It is classified into pure desmoplastic melanoma (PDM) when the proportion of desmoplastic melanoma is ≥90% of the dermally-invasive component, and mixed desmoplastic melanoma (MDM) when the proportion of desmoplastic melanoma is <90%. Studies have reported a lower sentinel lymph node biopsy (SLNB)-positivity rate in PDM compared to MDM and non-DM. As a result, some have recommended not performing SLNB in PDM patients. When PDM is identified in a partial biopsy of a melanoma, there is a risk that sampling bias may under-recognise MDM, but to the best of our knowledge this has not been previously assessed or quantified. The aim of this study was to assess the concordance of the proportion of desmoplastic melanoma in an initial partial biopsy of PDM with the proportion in the entire tumour following complete excision, in patients with cutaneous melanoma. A secondary aim was to determine how frequently this potentially resulted in a patient not receiving a SLNB. Seventy-eight cases of cutaneous melanoma were identified from the Melanoma Institute Australia (MIA) database and 23 cases from the Memorial Sloan Kettering Cancer Centre (MSKCC), where an initial biopsy contained PDM and a subsequent wide excision had residual invasive melanoma. Clinicopathological features were analysed in all patients, including whether a SLNB was performed, the results of SLNB, and any subsequent recurrence. Ninety percent (91/101) of cases were still classified as PDM in the complete wide excision specimen while 10% (10/101) of cases were reclassified as MDM, which was a significant change in classification of final desmoplastic melanoma subtype (p<0.001). The proportion of desmoplastic melanoma was also significantly different between the initial and excisional biopsies (p=0.004). Forty-eight (48/101) patients had a SLNB, of which two (4.5%) were positive for metastatic melanoma; both cases were PDM in the excision specimen. Of the 10 cases demonstrating MDM in the excision specimen, the initial biopsy was a punch biopsy in six cases, shave biopsy in two cases and subcutaneous tissue was sampled in two patients (one punch biopsy, one incisional biopsy). Four of these 10 patients underwent SLNB which was negative in all cases. Twenty-two patients developed recurrence in the follow-up period (median 30 months, range 1-192 months), three with MDM in their excision specimen. One patient did not have a SLNB and developed regional lymph node recurrence. In this study there was a 10% risk that the percentage of desmoplastic melanoma in an initial biopsy of PDM was not representative of the entire lesion, resulting in reclassification as MDM in the excision specimen. If a SLNB is not performed in such cases, a positive SLNB may be missed (one patient in our study) which could impact treatment options for the patient. We recommend caution in not offering a SLNB in the setting of an initial biopsy of PDM if the biopsy is small compared with the overall lesion. If a SLNB is not procured at the time of wide excision in such cases, the SLNs should still be mapped by lymphoscintigraphy to facilitate careful follow up and to enable earlier detection and treatment of nodal disease.

Interobserver agreement in the histopathological classification of desmoplastic melanomas

Desmoplastic melanoma is a subtype of melanoma characterised by amelanotic fusiform melanocytes dispersed in a collagenous stroma. Cell-poor and fibrous stroma-rich 'pure' variants have been distinguished from 'mixed' variants with areas of higher cell density and/or less desmoplastic stroma. This distinction is relevant because patients whose tumours display a pure phenotype have a lower risk for regional lymph node metastasis and distant recurrence. However, little is known about interobserver agreement among pathologists in the subclassification of desmoplastic melanoma. To address this issue, we conducted a study in which eleven dermatopathologists independently evaluated whole slide scanned images of excisions from 30 desmoplastic melanomas. The participating pathologists were asked to classify the tumours as pure or mixed. They were also asked to record the presence or absence of neurotropism and angiotropism. We found substantial interobserver agreement between the 11 dermatopathologists in the classification of tumours as pure versus mixed desmoplastic melanoma (kappa=0.64; p<0.0001). There was fair agreement between the 11 dermatopathologists in the evaluation of presence versus absence of neurotropism (kappa=0.26; p<0.0001), and slight agreement in the assessment of angiotropism (kappa=0.13; p<0.0001). The level of concordance in the subclassification of desmoplastic melanomas is encouraging for the acceptance of this prognostic parameter in the real-world practice of melanoma pathology.

Sentinel lymph node biopsy in desmoplastic melanoma - the percent desmoplastic component matters: A systematic review

BACKGROUND

Desmoplastic melanoma (DM) is a less common form of cutaneous melanoma that has been described for decades; however, controversy remains regarding the management and use of sentinel lymph node biopsy (SLNB). The purpose of this study is to identify whether SLNB is indicated in all cases of DM, including the pure subtype.

METHODS

A systematic review was conducted using PubMed (with access to MEDLINE) along with the Cochrane Central Register of Controlled Trials from 2001 to 2019. Case series and case-control studies were included.

RESULTS

Eighteen studies were included for a total population of 3,914 patients. SLNB was performed in 2229 patients. The percentage of positive SLNB results was 8.5%. However, patients with pure DM (>90% desmoplastic component) were found to have a significantly lower rate of occult metastatic node positivity when compared with that of mixed DM (4.9% and 14.8%, respectively).

CONCLUSIONS

Our findings underscore the importance of the pathologist reporting percentage of desmoplastic component in melanoma. SLNB should be strongly considered for patients with mixed DM. However, the low rate of occult metastatic node positivity in pure DM is beneath the threshold for using SLNB as a staging procedure.

SUMMARY

Previous studies have suggested that desmoplastic melanoma is less likely to metastasize to regional lymph nodes when compared with conventional melanoma. This review suggests that it is imperative to distinguish the histologic subtype of desmoplastic melanoma to determine if staging procedure is indicated.

Desmoplastic melanoma: a review of its pathology and clinical behaviour, and of management recommendations in published guidelines

Desmoplastic melanomas are uncommon. Their behaviour differs from that of other melanoma subtypes; therefore, management guidelines for non-desmoplastic melanomas may not be applicable. This review sought to examine all available evidence relating to the behaviour and management of desmoplastic melanomas, based on review of all relevant English-language publications, and to critically assess the recommendations for their management in current published melanoma management guidelines. Compared with other melanoma subtypes, patients with 'pure' desmoplastic melanomas (where ≥90% of the invasive melanoma is of desmoplastic melanoma subtype) have much lower rates of sentinel node positivity and distant metastasis. Local recurrence rates are higher for desmoplastic melanomas, but resection margins wider than those recommended for non-desmoplastic melanomas have not been shown to be of benefit. Adjuvant radiotherapy reduces the risk of local recurrence when a satisfactory histological clearance (≥8 mm) cannot be achieved. Of 29 published melanoma management guidelines identified, only 11 specified management for desmoplastic melanomas, while seven simply stated that the feature should be reported. Desmoplastic melanoma is a unique melanoma subtype with biology that differs from that of other melanoma subtypes. It requires specific management strategies but few current guidelines address these.

Re-evaluation of Sentinel Lymph Node Biopsy for Melanoma

OPINION STATEMENT

The vast majority of patients newly diagnosed with melanoma present with clinically localized disease, and sentinel lymph node biopsy (SLNB) is a standard of care in the management of these patients, particularly in intermediate thickness cases, in order to provide important prognostic data. However, SLNB also has an important role in the management of patients with other subtypes of melanoma such as thick melanomas, certain thin melanomas, and specific histologic variants of melanoma such as desmoplastic melanoma. Furthermore, there have been technical advances in the SLNB technique, such as the development of newer radiotracers and use of SPECT/CT, and there is some data to suggest performing a SLNB may be therapeutic. Finally, the management of patients with a positive sentinel lymph node (SLN) has undergone dramatic changes over the past several years based on the results of recent important clinical trials. Treatment options for patients with SLN metastases now include surveillance, completion lymph node dissection, and adjuvant therapy with checkpoint inhibitors and targeted therapy. SLNB continues to play a crucial role in the management of patients with melanoma, allowing for risk stratification, potential regional disease control, and further treatment options for patients with a positive SLN.

Desmoplastic melanoma: an updated clinical review and the emerging role of genetic markers and immunotherapies

Desmoplastic melanoma (DM) is a rare and histopathologically as well as prognostically distinct subset of melanoma that arises in chronically sun-damaged skin. DM is typically and relatively indolent in nature with most cases not progressing to metastatic disease. DM has been managed with both radiation and surgical approaches. Medical options for the treatment of metastatic DM have traditionally been limited. Recent advances in immunotherapies have shown promising responses in DM ushering in a new class of treatment options. Additionally, with the advent of whole exome sequencing, the genetic make-up of DM has been further characterized creating new possibilities for future targeted therapies.

Differing biologic behaviors of desmoplastic melanoma subtypes: Insights based on histopathologic, immunohistochemical, and genetic analyses

Desmoplastic melanoma (DM) is an uncommon variant of melanoma that can be challenging to diagnose. Phenotypic variations in terms of the proportion of spindled cells and fibromucinous stroma have led to the subclassification of pure (>90% spindled cells) and mixed (<90% spindled cells admixed with epithelioid cells) histopathologic DM subtypes. This subclassification is not just semantic; several studies have underscored differences in clinical and prognostic behaviors of the subtypes. In this review, we parse the literature on DM subtypes with an emphasis on histopathologic, immunohistochemical, and genetic data to ascertain whether these factors influence and/or affect their differing biological behaviors. Demographics regarding age, location, and clinical behavior of the subtypes are detailed, as is the impact of dermoscopy as a diagnostic adjunct. Despite the plethora of markers used, our findings suggest that few differentiate between the DM subtypes. Differential expression of PD-L1 suggests that patients with the mixed subtype are likely better candidates for anti-PD/PD-L1 therapy. Significant differences between the subtypes in terms of neurofibromin expression and the frequency of TERT promoter mutations suggest that the subtypes have distinct genetic drivers. Thus, immunohistochemical and genetic analyses imply that these likely affect the biological behaviors of the DM subtypes.

Desmoplastic melanoma: The role of pure and mixed subtype in sentinel lymph node biopsy and survival

Background

Desmoplastic melanoma (DM) is an uncommon type of melanoma. Two histological subtypes of DM can be distinguished: pure and mixed (PDM and MDM). We hypothesized that discrimination between these subtypes is associated with sentinel lymph node biopsy (SLNB) status and survival.

Methods

Clinicopathological data from PALGA, the Dutch Pathology Register were retrieved from patients diagnosed with DM in The Netherlands between 2000 and 2014. Clinical and pathological variables were extracted from pathology text files, including pure or mixed desmoplastic morphology. A Cox proportional hazard model was performed for overall and recurrence‐free survival (OS and RFS).

Results

A total of 239 patients with DM were included, representing 0.4% of all primary cutaneous melanoma in The Netherlands. A total of 114 PDM and 125 MDM patients were identified. MDM was significantly associated with positive SLNB status (P = .035). In multivariable analysis, age (HR 1.10, 95% CI 1.07‐1.14, P < .001) and ulceration (HR 1.98, 95% CI 1.05‐3.75, P = .036) were significant predictors for OS. For RFS, mixed subtype (HR 2.72 95% CI 1.07‐6.89, P = .035), male gender (HR 2.54, 95% CI 1.03‐6.27, P = .043), and Breslow thickness (HR 1.13 per mm, 95% CI 1.05‐1.21, P = .001) were significant predictors.

Conclusion

MDM is significantly associated with a positive SLNB status. Mixed subtype is significantly correlated with RFS, but not with OS. The distinction between pure and mixed desmoplastic subtype therefore seems to be of clinical importance.

Predictors of occult lymph node metastasis in cutaneous head and neck melanoma

OBJECTIVE

To use the Surveillance, Epidemiology, and End Results (SEER) database to verify the findings of a recent National Cancer Database (NCDB) study that identified factors predicting occult nodal involvement in cutaneous head and neck melanoma (CHNM) while identifying additional predictors of occult nodal metastasis and comparing two distinct cancer databases.

METHODS

Cases of CHNM in the SEER database diagnosed between 2004 and 2014 were identified. Demographic information and oncologic data were obtained. Univariate and multivariate analysis were performed to identify factors associated with pathologic nodal positivity.

RESULTS

There were 34002 patients with CHNM identified. Within this population, 16232 were clinically node-negative, 1090 of which were found to be pathologically node-positive. On multivariate analysis, factors associated with an increased risk of occult nodal metastasis included increasing depth of invasion (stepwise increase in adjusted odds ratio [OR]), nodular histology (aOR: 1.47 [95% CI: 1.21-1.80]), ulceration (aOR: 1.74 [95% CI: 1.48-2.05]), and mitoses (aOR: 1.86 [95% CI: 1.36-2.54]). Factors associated with a decreased risk of occult nodal metastasis included female sex (aOR: 0.80 [0.67-0.94]) and desmoplastic histology (aOR: 0.37 [95% CI: 0.24-0.59]). Between the SEER database and the NCDB, factors associated with occult nodal involvement were similar except for nodular histology and female sex, which did not demonstrate significance in the NCDB.

CONCLUSION

Regarding clinically node-negative CHNM, the SEER database and the NCDB have similarities in demographic information but differences in baseline population sizes and tumor characteristics that should be considered when comparing findings between the two databases.

LEVEL OF EVIDENCE

4.

Pathology of Melanoma

Melanoma is an aggressive malignancy arising from melanocytes in the skin and rarely in extracutaneous sites. The understanding of pathology of melanoma has evolved over the years, with the initial classifications based on the clinical and microscopic features to the current use of immunohistochemistry and genetic sequencing. The depth of invasion and lymph node metastasis are still the most important prognostic features of melanoma. Other important prognostic features include ulceration, lymphovascular invasion, mitosis, and tumor-infiltrating lymphocytes. This article reviews the pathology of melanoma and its precursor lesions, along with the recent advances in pathologic diagnosis of melanoma.

Mixed Versus Pure Variants of Desmoplastic Melanoma: The Cleveland Clinic Experience

BACKGROUND

Desmoplastic melanoma (DM) is a subvariant of spindle cell melanoma, accounting for less than 4% of all cutaneous melanomas. It occurs later in life and is associated with chronic sun exposure. Desmoplastic melanoma prognosis is considered more favorable than other variants, with lower rates of metastasis and higher survival. Recently, DM has been further subclassified into pure and mixed, calling into question surgical management and patient outcomes as well as viability of current nationwide databases without this distinction.

METHODS

We identified all patients with a histopathologic diagnosis of DM from the Cleveland Clinic electronic melanoma database (n = 58) from 1997 to 2013. Clinical and histopathologic data were collected. Comparison in clinical variables was performed between patients who had pure (n = 15) and mixed (n = 43) variants of DM.

RESULTS

There were no differences in age, sex, location of lesion, Breslow depth, ulceration, or regression. Patients with mixed DM were more likely to have lymphovascular invasion (P = 0.03) compared with pure DM. There was no difference in performance of sentinel lymph node biopsy (P = 0.25) or sentinel lymph node positivity (P = 0.31) between the 2 groups. Recurrence was present in 13.3% of pure and 30.2% of mixed patients. Overall, Kaplan-Meier 3-year survival was 75% for pure and 80% for mixed DM (P = 0.53).

CONCLUSIONS

Pure and mixed DMs seem to have similar clinical characteristics and outcomes. This indicates that analysis of national datasets without this subclassification remains viable.

Desmoplastic melanoma: Demographic and clinicopathological features and disease-specific prognostic factors

Desmoplastic melanoma (DM) is a rare morphological subtype of melanoma that remains uncharacterized. The aim of the present study was to investigate the incidence of DM, its general demographics, clinicopathological features and disease-specific prognostic factors. DM cases were sampled from the Surveillance, Epidemiology and End Results (SEER) program from between 1973 and 2017. A total of 3,657 cases (median age, 68 years) were identified. The results indicated that DM primarily occurred in Caucasian subjects, with a male-to-female ratio of 2:1. Statistically significant overall survival (OS) and disease-specific survival (DSS) rate differences were identified according to sex, age, treatment, T stage, N stage and SEER historic tumor stage (P<0.05). In multivariate Cox regression analysis, age >68 years, male sex, American Joint Committee on Cancer (AJCC) stage II and III, and SEER historic tumor stage of the regional tumor were all factors associated with poorer OS and DSS rates. The findings also revealed that surgical treatment was associated with favorable DSS and OS rates. In conclusion, DM occurred primarily in Caucasian subjects of 60–80 years of age, with predominance in males. Furthermore, age, sex, AJCC stage, SEER historic tumor stage and surgical treatment were identified as independent prognostic factors of DM in terms of DSS and OS.

Desmoplastic melanoma: a rare variant with challenging diagnosis

Desmoplastic melanoma, a distinct and uncommon variant, is characterized as an invasive lesion with proliferation of fusiform melanocytes in the dermis and subcutaneous tissue, associated with varying patterns of desmoplasia. Neurotropism and neural differentiation may occur. The clinical presentation is variable and nonspecific, easily confused with other fibrous neoplasms. The disease is locally aggressive and shows lower metastasis rates than other types of melanoma. Histopathology may be insufficient, requiring positive immunohistochemistry for S-100 protein and other antigens of melanocytic differentiation. Because desmoplastic melanoma represents a true clinical, dermoscopic, and histopathological diagnostic challenge, a case of invasive desmoplastic melanoma is reported, affecting a photoexposed area in an elderly woman after histological revisions and an initial diagnosis of fibroma.

Desmoplastic melanoma

Desmoplastic melanoma (DM) is a rare melanoma variant that has unique biology and pathology compared with conventional melanoma (non-DM). Importantly, DM is classified into pure and mixed histologic subtypes, which have been correlated with outcomes. Management of DM broadly mirrors that of non-DM; however, there are unique considerations for DM that influence treatment approaches. This paper will provide a contemporary overview of this disease and will review the literature regarding the management of DM.

Lymphoid aggregates in desmoplastic melanoma have features of tertiary lymphoid structures

Desmoplastic melanomas (DM) have unique and challenging clinical presentations and histomorphology. A characteristic feature is the presence of scattered lymphoid aggregates. However, the nature of these aggregates is not defined. We hypothesized that they may be tertiary lymphoid structures (TLS), and may be associated with programmed death ligand 1 (PD-L1) expression. We searched our tissue database for 'pure' DMs and for scars as control tissues, collected clinical information, and reviewed H&E histology. We performed multispectral imaging after staining for CD8, CD20, PNAd, FoxP3, CD83, and Ki67, and assessed PD-L1 expression by immunohistochemistry. Pure DM samples were evaluable in 11 patients. All had desmoplastic stroma and lymphoid aggregates on H&E. The lymphoid aggregates of eight of the 11 (72%) DM samples and only three of the 11 scars contained features of TLS, defined as distinct clusters of B cells and CD8 T cells, CD83 dendritic cells in T-cell zones, and PNAd vasculature resembling high endothelial venules. PD-L1 was expressed by at least 1% of melanoma cells in six and by at least 5% of immune cells in 10 of the 11 DM samples. We found that most lymphoid aggregates in DM are organized, classical TLS. PD-L1 expression was detected in most cases and was highest in two cases of DM with TLS. However, low PD-L1 expression in some cases suggests that some DM cells may be unresponsive to interferon-γ. TLS support antigen presentation and T-cell responses in chronic inflammation and cancer. Their presence in DM likely reflects an adaptive immune response, which may be enhanced with immune therapies.

Desmoplastic Melanoma of the Head and Neck: Incidence and Survival, 1992-2013

Objective To describe the epidemiological characteristics and survival of desmoplastic melanoma of the head and neck (DMHN) and discuss the factors influencing survival variation among DMHN, DM of other sites (DMnHN), and conventional melanoma of the head and neck (CMHN). Study Design Retrospective cohort study. Setting Surveillance, Epidemiology, and End Results (SEER) database (years 1992-2013). Subjects and Methods Incidence and survival data for 1095 patients with DMHN, 1139 patients with DMnHN, and 40,257 patients with CMHN were obtained. Kaplan-Meier and Cox proportional hazards regression models were used to calculate survival outcomes. Results Patients with DMHN were diagnosed at greater Breslow thickness ( P < .001), stage ( P < .001), and Clark's level ( P < .001) compared to DMnHN and CMHN. Kaplan-Meier survival analysis demonstrated disease-specific survival (DSS) at 5 and 10 years for DMHN to be 80.5% and 74.7%, respectively, compared with 89.1% and 86%, respectively, for DMnHN and 88.1% and 83%, respectively, for CMHN (log-rank test; P < .001). On multivariate Cox regression analysis, age at diagnosis ( P < .001), Breslow depth >4.00 mm ( P = .006), lymph node status ( P < .001), and presence of ulceration ( P < .001) were found to be independent predictors of DSS for DMHN. Conclusion The increasing incidence and poor survivability of DMHN compared to DMnHN and CMHN are parsimoniously explained by the later stage of disease and depth of invasion at diagnosis, highlighting the importance of improved diagnosis and awareness of DMHN.

Head and neck desmoplastic melanoma: Utility of sentinel node biopsy

PURPOSE

The utility of sentinel lymph node biopsy in desmoplastic melanoma has been questioned due to multiple reports of a low rate of occult nodal metastasis in this variant of melanoma. We describe a single institution experience with management of desmoplastic melanoma of the head and neck and discuss the utility of sentinel lymph node biopsy.

MATERIALS AND METHODS

A retrospective review was performed of 49 patients with desmoplastic melanoma of the head and neck at a tertiary care center from 1994 to 2014.

RESULTS

Sentinel lymph node biopsy was performed in 15 patients. Only 1 (6.7%) of these patients was found to have a positive sentinel node. Of the 46 patients without evidence of neck disease at presentation, 3 (6.5%) were found to have occult nodal disease or developed neck recurrences. When looking at the entire cohort, there were a total of 16 recurrences in 14 patients (28.6%). The majority (85.7%) of recurrences were either local or distant metastasis with only 2 (14.3%) recurrences being in regional lymph node basins. The overall rates of local, regional, and distant recurrences were 14.2%, 4.1%, and 10.2% respectively. The mixed pathologic subtype was not associated with a higher rate of nodal metastasis.

CONCLUSIONS

Desmoplastic melanoma has a low rate of occult nodal metastasis and a high propensity to recur locally or as a distant metastasis, regardless of regional node status. Our experience combined with the uncertain impact that sentinel node status has on survival raises the question of the utility of routine sentinel node biopsy in this specific variant of melanoma.

Is sentinel lymph node biopsy warranted for desmoplastic melanoma? A systematic review

BACKGROUND

Desmoplastic melanoma (DM) is an uncommon malignancy associated with a high local recurrence rate. The aim of this systematic review was to determine the positivity rate of sentinel lymph node biopsy (SLNB) in patients with DM. The secondary outcome was to establish if SLNB is warranted for both pure DM (PDM) and mixed DM (MDM).

METHODS

A full systematic literature review of SLNB in DM was performed by two authors in January 2016. Ovid MEDLINE, Ovid EMBASE and the Cochrane Central Register of Controlled Trials were searched.

RESULTS

Sixteen studies involving 1519 patients having SLNB in DM were included, of which 99 patients had positive SLNB (6.5%). Two articles reported a significantly reduced disease-free survival (DFS) with positive SLNB and three published a reduced melanoma-specific survival (MSS). Six studies compared SLNB in MDM and PDM. Of the 275 patients, 38 (13.8%) had a positive SLNB in MDM compared to 17 of 313 patients (5.4%) with positive SLNB in PDM.

CONCLUSIONS

Rates of positive SLNB in DM are reduced compared to other variants of melanoma; however, nodal status may still predict DFS and MSS. MDM is associated with a higher rate of micro-metastases to regional lymph nodes than PDM, and DFS and MSS may be lesser in MDM than in PDM. We would recommend the consideration of SLNB in MDM. However, with such low rates of positive SLNB in PDM, and in the absence of high-risk features to stratify patients, we would not recommend SLNB in PDM.

Malignant Melanoma: Beyond the Basics

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Discuss the initial management of cutaneous malignant melanoma with regard to diagnostic biopsy and currently accepted resection margins. 2. Be familiar with the management options for melanoma in specific situations such as subungual melanoma, auricular melanoma, and melanoma in the pregnant patient. 3. Discuss the differentiating characteristics of desmoplastic melanoma and its treatment options. 4. List the indications for sentinel lymph node biopsy and be aware of the ongoing trials and current literature. 5. Discuss the medical therapies available to patients with metastatic melanoma.

SUMMARY

Management of the melanoma patient is a complex and evolving subject. Plastic surgeons should be aware of the recent changes in the field. Excisional biopsy remains the gold standard for diagnosis, although there is no evidence that use of other biopsy types alters survival or recurrence. Wide local excisions should be carried out with margins as recommended by National Comprehensive Cancer Network guidelines according to lesion Breslow depth, with sentinel lymph node biopsy being offered to all medically suitable candidates with intermediate thickness melanomas (1.0 to 4.0 mm), and with sentinel lymph node biopsy being considered for high-risk lesions (ulceration and/or high mitotic figures) with melanomas of 0.75 to 1.0 mm. Melanomas diagnosed during pregnancy can be treated with preoperative lymphoscintigraphy and wide local excision under local anesthesia, with sentinel lymph node biopsy under general anesthesia delayed until after delivery. Management of desmoplastic melanoma is currently controversial with regard to the indications for sentinel lymph node biopsy and the efficacy of postoperative radiation therapy. Subungual and auricular melanoma have evolved from being treated by amputation of the involved appendage to less radical procedures-ear reconstruction is now attempted in the absence of gross invasion into the perichondrium, and subungual melanomas may be treated with wide local excision down to and including the periosteum, with immediate full-thickness skin grafting over bone. Although surgical treatment remains the current gold standard, recent advances in immunotherapy and targeted molecular therapy for metastatic melanoma show great promise for the development of medical therapies for melanoma.

Clinical utilities and biological characteristics of melanoma sentinel lymph nodes

An estimated 73870 people will be diagnosed with melanoma in the United States in 2015, resulting in 9940 deaths. The majority of patients with cutaneous melanomas are cured with wide local excision. However, current evidence supports the use of sentinel lymph node biopsy (SLNB) given the 15%-20% of patients who harbor regional node metastasis. More importantly, the presence or absence of nodal micrometastases has been found to be the most important prognostic factor in early-stage melanoma, particularly in intermediate thickness melanoma. This review examines the development of SLNB for melanoma as a means to determine a patient’s nodal status, the efficacy of SLNB in patients with melanoma, and the biology of melanoma metastatic to sentinel lymph nodes. Prospective randomized trials have guided the development of practice guidelines for use of SLNB for melanoma and have shown the prognostic value of SLNB. Given the rapidly advancing molecular and surgical technologies, the technical aspects of diagnosis, identification, and management of regional lymph nodes in melanoma continues to evolve and to improve. Additionally, there is ongoing research examining both the role of SLNB for specific clinical scenarios and the ways to identify patients who may benefit from completion lymphadenectomy for a positive SLN. Until further data provides sufficient evidence to alter national consensus-based guidelines, SLNB with completion lymphadenectomy remains the standard of care for clinically node-negative patients found to have a positive SLN.

Diagnostic Challenge of Desmoplastic Melanoma

Desmoplastic melanoma (DM) is a rare variant of spindle-cell malignant melanoma. DM is easily misdiagnosed at an early stage because it can be confused with benign entities. Histological analysis, including careful attention to the presence of atypical spindle cells, as well as to lymphocytic aggregates in an abundant fibrotic stroma in the dermis, provides clues for diagnosis. The adjunction of an immunohistochemical panel, and particularly testing for S-100 protein, is needed for the final diagnosis.

NF1 Mutations Are Common in Desmoplastic Melanoma

Desmoplastic melanoma (DM) is a rare variant of melanoma with distinct clinical, histopathologic, and immunohistochemical features. Clinically, DM differs from conventional melanoma by a higher propensity for local recurrence and less frequent metastatic spread to regional lymph nodes. In its pure form, DM has a distinct appearance displaying a low density of fusiform melanocytes in a collagen-rich matrix. Whereas a number of mutations have been identified in primary melanoma, including BRAF, NRAS, GNAQ, GNA11, and KIT, and the occurrence of these mutations has been found to correlate to some extent with the histopathologic features, anatomic site, and/or mode of sun exposure, no distinct set of mutations has so far been reported for DM. To study the potential association of neurofibromin (NF1) mutations with DM, we examined 15 desmoplastic and 20 non-DMs by next-generation sequencing. Mutations of the NF1 gene were found in 14 of 15 (93%) DMs and 4 of 20 (20%) non-DMs. The high frequency of NF1 mutations in DMs suggests an important role for NF1 in the biology of this type of melanoma.

Primary Desmoplastic Melanoma of the Penis

Desmoplastic melanomas are rare amelanotic melanomas that usually occur on skin with sun exposure. In this report, we present a 72-year-old man who presented with a desmoplastic melanoma of the penis. To our knowledge this represents the first reported case of primary desmoplastic melanoma of the penis. We discuss the pathologic differential and histologic evaluation.

Mutational dichotomy in desmoplastic malignant melanoma corroborated by multigene panel analysis

Desmoplastic malignant melanoma is a distinct melanoma entity histologically subtyped into mixed and pure forms due to significantly reduced lymph node metastases in the pure form. Recent reports investigating common actionable driver mutations have demonstrated a lack of BRAF, NRAS, and KIT mutation in pure desmoplastic melanoma. In search for alternative driver mutations next generation amplicon sequencing for hotspot mutations in 50 genes cardinal to tumorigenesis was performed and in addition the RET G691S polymorphism was investigated. Data from 21 desmoplastic melanomas (12 pure and 9 mixed) were retrieved. Pure desmoplastic melanomas were either devoid of mutations (50%) or displayed mutations in tumor suppressor genes (TP53, CDKN2A, and SMAD4) singularly or in combination with the exception of a PIK3CA double-mutation lacking established biological relevance. Mixed desmoplastic melanomas on the contrary were frequently mutated (89%), and 67% exhibited activating mutations similar to common-type cutaneous malignant melanomas (BRAF, NRAS, FGFR2, and ERBB2). Separate analysis of morphologically heterogeneous tumor areas in four mixed desmoplastic malignant melanomas displayed no difference in mutation status and RET G691 status. GNAQ and GNA11, two oncogenes in BRAF and NRAS wild-type uveal melanomas, were not mutated in our cohort. The RET G691S polymorphism was found in 25% of pure and 38% of mixed desmoplastic melanomas. Apart from RET G691S our findings demonstrate absence of activating driver mutations in pure desmoplastic melanoma beyond previously investigated oncogenes (BRAF, NRAS, and KIT). The findings underline the therapeutic dichotomy of mixed versus pure desmoplastic melanoma with regard to activating mutations primarily of the mitogen-activated protein kinase pathway.

Clinicopathologic predictors of survival in patients with desmoplastic melanoma

Background and Objectives

Desmoplastic melanoma is a unique subtype of melanoma which typically affects older patients who often have comorbidities that can adversely affect survival. We sought to identify melanoma-specific factors influencing survival in patients with desmoplastic melanoma.

Methods

Retrospective review from 1993 to 2011 identified 316 patients with primary desmoplastic melanoma. Clinicopathologic characteristics were correlated with nodal status and outcome.

Results

Fifty-five patients (17.4%) had nodal disease: 33 had a positive sentinel lymph node biopsy and 22 developed nodal recurrences (no sentinel lymph node biopsy or false-negative sentinel lymph node biopsy). Nodal disease occurred more often in younger patients and in cases with mixed compared with pure histology (26.7% vs. 14.6%); both of these variables significantly predicted nodal status on multivariable analysis (p<0.05). After a median follow-up of 5.3 years, recurrence developed in 87 patients (27.5%), and 111 deaths occurred. The cause of death was known in 79 cases, with 47 deaths (59.5%) being melanoma-related. On multivariable analysis, Breslow thickness, mitotic rate ≥1/mm² and nodal status significantly predicted melanoma-specific survival (p<0.05).

Conclusions

Nodal status predicts melanoma-specific survival in patients with desmoplastic melanoma. However, since patients with desmoplastic melanoma represent an older population, and a considerable proportion of deaths are not melanoma-related (40.5%), comorbidities should be carefully considered in making staging and treatment decisions in this population.

[Desmoplastic melanoma: a study of 23 cases at 3 centres in the Bouches-du-Rhône region]

BACKGROUND

Desmoplastic melanoma (DM) is a rare form of melanoma, often with atypical and potentially misleading aspects that result in difficult and late diagnosis. Because of the high likelihood of local relapse, practitioners must have a good knowledge of such tumours.

PATIENTS AND METHODS

A retrospective study of the activities of 3 centres in the Bouches-du-Rhône region between 1998 and 2010 enabled us to collate 23 cases of DM and analyse the clinical and histological features of the disease as well as patient survival.

RESULTS

Fifteen of the 23 patients (65.2%) were male with a median age of 64.4 years. Mean Breslow thickness was 7.56 mm. The numbers of AJCC (American Joint Committee for Cancer) stages I, II, III, IV were respectively 4.1, 66.7, 20.8 and 4.1%. Thirteen patients presented relapse, with a mean time to onset of 21 months. The initial relapse involved the skin in 1 case, the lymph nodes in 2 cases, the organs in 5 cases, the organs and subcutaneous region in 1 case, the organs and lymph nodes in 2 cases, and the organs, lymph nodes and skin in 1 case.

DISCUSSION

While DM presents a higher rate of local relapse than classical melanoma, this trend appears to subside in the case of thick DM, in which relapse also involves the lymph nodes and/or organs.

The role of adjuvant radiotherapy in the local management of desmoplastic melanoma

BACKGROUND

In the current study, the authors sought to evaluate outcomes, specifically with respect to adjuvant radiotherapy (RT), for patients with desmoplastic melanoma.

METHODS

The records of 130 consecutive patients who presented between 1985 and 2009 with nonmetastatic desmoplastic melanoma and were treated curatively with either surgery alone (59 patients; 45%) or surgery and postoperative RT (71 patients; 55%) were retrospectively reviewed. Ages ranged from 21 years to 97 years (median age, 66 years). The location of the primary tumor was in the head and neck region in 62% of patients. Only 5 patients (4%) had lymph node involvement at the time of presentation.

RESULTS

The median follow-up was 6.6 years (range, 11 months-24 years). Overall survival rates at 5 years and 10 years were 69% and 53%, respectively. Disease-specific survival rates were 84% and 80%, respectively, at 5 years and 10 years. The actuarial rate of local recurrence was 17% at 5 years and beyond. Of the patients who underwent surgery without receiving postoperative RT, 14 (24%) experienced local recurrence. Of the 71 patients treated with surgery and postoperative RT, 5 (7%) experienced local recurrence. In a Cox multivariate regression model, improved local control was significantly associated with the receipt of postoperative RT (P= .009).

CONCLUSIONS

Surgery followed by postoperative RT appears to provide superior local control compared with surgery alone for patients with desmoplastic melanoma.

Data set for pathology reporting of cutaneous invasive melanoma: recommendations from the international collaboration on cancer reporting (ICCR)

An accurate and complete pathology report is critical for the optimal management of cutaneous melanoma patients. Protocols for the pathologic reporting of melanoma have been independently developed by the Royal College of Pathologists of Australasia (RCPA), Royal College of Pathologists (United Kingdom) (RCPath), and College of American Pathologists (CAP). In this study, data sets, checklists, and structured reporting protocols for pathologic examination and reporting of cutaneous melanoma were analyzed by an international panel of melanoma pathologists and clinicians with the aim of developing a common, internationally agreed upon, evidence-based data set. The International Collaboration on Cancer Reporting cutaneous melanoma expert review panel analyzed the existing RCPA, RCPath, and CAP data sets to develop a protocol containing "required" (mandatory/core) and "recommended" (nonmandatory/noncore) elements. Required elements were defined as those that had agreed evidentiary support at National Health and Medical Research Council level III-2 level of evidence or above and that were unanimously agreed upon by the review panel to be essential for the clinical management, staging, or assessment of the prognosis of melanoma or fundamental for pathologic diagnosis. Recommended elements were those considered to be clinically important and recommended for good practice but with lesser degrees of supportive evidence. Sixteen core/required data elements for cutaneous melanoma pathology reports were defined (with an additional 4 core/required elements for specimens received with lymph nodes). Eighteen additional data elements with a lesser level of evidentiary support were included in the recommended data set. Consensus response values (permitted responses) were formulated for each data item. Development and agreement of this evidence-based protocol at an international level was accomplished in a timely and efficient manner, and the processes described herein may facilitate the development of protocols for other tumor types. Widespread utilization of an internationally agreed upon, structured pathology data set for melanoma will lead not only to improved patient management but is a prerequisite for research and for international benchmarking in health care.

Incidence of sentinel lymph node involvement in a modern, large series of desmoplastic melanoma

BACKGROUND

Recent studies have suggested that sentinel lymph node (SLN) biopsy is of limited value in desmoplastic melanoma. This study was performed to compare the rate of positive SLN biopsy in the Surveillance, Epidemiology, and End Results (SEER) database with that of a multi-institutional clinical trial and to investigate relevant prognostic factors in desmoplastic melanoma.

STUDY DESIGN

Patients with desmoplastic melanoma ≥1.0 mm Breslow thickness, who underwent SLN biopsy in a multi-institutional prospective clinical trial, were combined with a single institution melanoma database (combined database) and compared with patients from the SEER database (1998 to 2009). Disease-free survival (DFS) and overall survival (OS) were summarized using Kaplan-Meier curves and compared using Cox proportional hazard models.

RESULTS

The rate of positive SLN in the combined database was 17.0% (8 of 47). By comparison, the rate of positive SLN in SEER was lower: 2.5% (15 of 594). On multivariable analysis, Breslow thickness ≥2.6 mm (hazard ratio 8.17, 95% CI 1.26 to 160.1; p = 0.0259) and an interaction between SLN status and ulceration (p = 0.0013) were independent risk factors for worse OS in the combined database; patients with ulceration and a positive SLN had significantly worse OS. In the combined database on multivariable analysis, SLN positivity (p = 0.0161) and ulceration (p = 0.0004) were independent risk factors for worse DFS.

CONCLUSIONS

The rate of positive SLN in desmoplastic melanoma may be higher than that reported in the SEER database. Sentinel lymph node biopsy may be considered as part of the comprehensive staging of desmoplastic melanoma ≥1.0 mm Breslow thickness.

Desmoplastic melanoma: a review

Desmoplastic melanoma (DM) is a variant of spindle cell melanoma typically found on chronically sun-damaged skin of older individuals. Early diagnosis can be challenging because it is often amelanotic and has a predominantly dermal component. DM can be difficult to diagnose not only clinically but also histologically, and can be mistaken for a variety of benign and malignant nonmelanocytic spindle cell tumors when viewed on prepared histopathology slides. Pathologists have observed that DMs can manifest significant variation with respect to the extent of intratumoral cellularity, fibrosis, and/or perineural invasion. Furthermore, some tumors present with a pure desmoplastic invasive component (>90%) while other tumors display mixed features of DM and nondesmoplastic melanoma. This has led to the separation of DM into 2 histologic subtypes, pure and mixed. With a focus on the distinction between pure and mixed DM, this review will detail what is currently known about the diagnostic features of DM, discuss risk and prognostic factors, and examine the current literature on disease progression and management.

Desmoplastic melanoma: is there a role for sentinel lymph node biopsy?

BACKGROUND

The utility of sentinel lymph node biopsy (SLNB) for desmoplastic melanoma (DM) is debated. We describe a large single-institution experience with SLNB for DM to determine clinicopathologic factors predictive of SLN metastasis.

METHODS

Retrospective review identified 205 patients with DM who underwent SLNB from 1992 to 2010. Clinicopathologic characteristics were correlated with SLN status and outcome.

RESULTS

Median age was 66 years, and 69 % of patients were male. Median Breslow thickness was 3.7 mm. In 128 cases (62 %), histologic subtype data was available; 61 cases (47.7 %) were mixed and 67 cases (52.3 %) were pure DM. A positive SLN was found in 28 cases (13.7 %); 24.6 % of mixed and 9 % of pure DM had SLN metastases. Multivariable analysis demonstrated that after controlling for age, histologic subtype correlated with SLN status [odds ratio: 3.0 for mixed vs pure, 95 % confidence interval: 1.1-8.7; p < .05]. Completion lymph node dissection was performed in 24 of 28 positive SLN patients with 16.7 % of cases having additional nodal disease. After a median follow-up of 6.3 years, 38 patients developed recurrence and 61 patients died. Positive SLN patients had a significantly higher risk of melanoma-related death compared with negative SLN patients (p = .01).

CONCLUSIONS

The overall risk for SLN metastasis for DM is 13.7 % and is significantly higher for mixed (24.6 %) compared with pure (9.0 %) DM. We believe that these rates are sufficient to justify consideration of SLNB for both histologic variants, especially since detection of SLN disease appears to predict a higher risk for melanoma-related death.

Desmoplastic malignant melanoma: a study of ten cases and status of BRAF mutation

BACKGROUND

Desmoplastic malignant melanoma (DM) is a rare variant of melanoma. BRAF gene mutations have been poorly explored in this entity.

OBJECTIVE

To detect BRAF gene mutation in a series of DM.

METHODS

This is a single-center retrospective study of ten patients with DM, with a biomolecular analysis of BRAF mutation.

RESULTS

The male:female ratio was 2.3:1, with a mean patient age of 66.5 years. Melanoma arose in the head and neck region in 3 cases. The mean tumor thickness was 7.97 mm, Clark level was IV or V in all cases. Six melanomas were of the pure DM variant. Three patients had at least one local recurrence, two had regional node metastases, and two experienced systemic metastases which they died of (average follow-up 34.1 months). A V600E BRAF mutation was detected in only one patient.

CONCLUSION

BRAF mutation seems to be a rare event in DM contrary to other melanoma variants.

Desmoplastic melanocytic nevi with lymphocytic aggregates

Desmoplastic melanocytic nevi can be difficult to distinguish from desmoplastic melanoma. The presence of lymphocytic aggregates in association with a sclerosing melanocytic proliferation is commonly regarded as a feature in support of a diagnosis of desmoplastic melanoma. However, the finding is not specific for melanoma. Herein we report six cases of sclerosing melanocytic nevi with associated lymphocytic aggregates. They occurred in five women and one man, ranging in age from 11 to 61 years. Three lesions were sclerosing Spitz nevi; one was an amelanotic sclerosing blue nevus, one an acquired intradermal sclerosing nevus, and one was a congenital compound melanocytic nevus with sclerosis of its dermal component. The lesions were interpreted as benign, i.e. melanocytic nevi, because of their histopathologic attributes (symmetric silhouette, benign cytologic features) and results from immunohistochemical studies (all lesions strongly expressed Melan-A and p16) and fluorescence in situ hybridization (FISH). Three lesions tested by FISH lacked copy number changes of 11p, 6q or 6p. None of the lesions recurred. The cases highlight that contextual information is essential for the diagnosis of desmoplastic melanoma and sclerosing nevus. The presence of lymphocytic aggregates per se does not prove that a sclerosing melanocytic proliferation is malignant.