Primary mucosal desmoplastic melanoma of the head and neck

Top 10 Differential Diagnoses for Desmoplastic Melanoma

BACKGROUND

Desmoplastic melanoma is a rare subtype of melanoma mainly appearing on sun-exposed skin. Clinically, it is many times non-pigmented and therefore the diagnosis is often not suspected.

METHODS

Review article.

RESULTS

In this paper we review the main histopathological, immunohistochemical, and molecular features of desmoplastic melanoma, as well as the top 10 morphologic differential diagnoses which should be considered in most cases. The histopathological pattern can be many times deceptive, mimicking a scar, a fibrous reaction, a fibrohistiocytic tumor such as a dermatofibroma, a vascular tumor such as angiosarcoma, a smooth muscle tumor such as leiomyosarcoma, or a neural tumor. Although an overlying atypical junctional melanocytic proliferation may be seen in most cases, it is absent in a significant percentage (up to 30%) of cases, making the diagnosis even more difficult in those instances. The range of diagnostic pitfalls is wide, which may present disastrous prognostic consequences.

CONCLUSION

Desmoplastic melanoma is often a difficult diagnosis to make, as it frequently shows nonspecific clinical findings and overlapping histologic features with many other tumors. However, the potential clinical and prognostic consequences of misdiagnosis as another entity are great. Therefore, this diagnosis must always be kept in mind when encountering spindle cell tumors affecting the head and neck area.

Nasal Mucosal Desmoplastic Melanoma: A Case Report with Review of the Literature

Mucosal melanoma is a rare subtype of melanoma that accounts for 1% of all melanomas. The incidence of nasal mucosal melanomas is 0.3 per million. Desmoplastic melanomas are a subtype of melanoma with a reported incidence of 2.0 per million. Although 50% of desmoplastic melanomas are found in the head and neck region, mucosal desmoplastic melanoma is exceedingly rare. In the present study, we report a case of nasal mucosal desmoplastic melanoma and review the literature. A 79-year-old female presented to an outside otolaryngologist with nasal discomfort accompanied by rhinorrhea and was found to have a nasal vestibule mass. An endonasal incisional biopsy was performed yielding a diagnosis of a SOX-10 positive tumor. The patient was referred to our institution for further management. A blue-tinged lesion was identified at the prior biopsy site, and the mass was resected via an open rhinoplasty approach. Final pathology demonstrated an infiltrative spindle cell neoplasm with immunohistochemical patterns supportive of desmoplastic melanoma arising from the nasal vestibule. Due to positive margins, the patient underwent a re-resection with no tumor identified on the re-resected specimen. To our knowledge, this is the third case of nasal mucosal desmoplastic melanoma. We review the clinicopathologic features and management of this rare entity.

Oral melanoma: a multicenter study of 69 patients from Japan

OBJECTIVES

The purpose of this multicenter retrospective study was to investigate the demographic characteristics and treatment outcomes of patients with mucosal malignant melanoma (MM) of the oral cavity.

MATERIALS AND METHODS

This was a multicenter study involving 8 Japanese universities. The medical records of 69 patients who were diagnosed with primary oral MM between January 2000 and December 2020 were retrospectively analyzed. Overall survival (OS) and prognostic factors for OS were analyzed statistically.

RESULTS

There were 40 (58.0%) males and 29 (42.0%) females, and their mean (range) age was 69.8 ± 14.6 (22-96) years old. The most common primary site was the palate (30 patients, 43.5%). Stage IVA was the most common disease stage (36 patients, 52.2%). Radical therapy was performed in 55 patients (79.7%). The 2-year and 5-year OS rates of the 69 patients were 64.6% and 42.5%, respectively. The 2-year and 5-year OS rates of the stage III patients were 85.9% and 72.5%, respectively, and those of the stage IVA patients were 56.3% and 26.0%, respectively. The 1-year OS rate of the stage IVB/IVC patients was 26.7%. The 2-year and 5-year OS rates of the radical therapy group were 74.1% and 50.5%, respectively, whereas the 2-year OS rate of the non-radical therapy group was 26.0%. An advanced T classification was the only identified prognostic factor for OS (hazard ratio: 6.312, 95% confidence interval: 1.133-38.522, p < 0.05).

CONCLUSIONS

Early detection and radical treatment are essential for improving the prognosis of oral MM patients.

CLINICAL RELEVANCE

Early detection and adequate radical therapy leads to the better prognosis of oral MM patients.

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.

Data Set for the Reporting of Mucosal Melanomas of the Head and Neck: Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting

Standardized pathologic reporting for cancers allows for improved communication for patient care and prognostic determination. If used universally, synoptic reporting enhances comparing data globally for scientific leverage. The International Collaboration on Cancer Reporting is a nonprofit organization whose mission is to develop evidence-based, universally available surgical pathology reporting data sets. Multiple different sites within the head and neck may be affected by mucosal melanoma, whose behavior and patient outcome are not equivalent to carcinomas of the corresponding sites. Factors such as Breslow thickness and Clark depth of invasion applied to cutaneous melanomas do not yield any prognostic significance in mucosal sites, and thus are not meaningful. Likewise, margin assessment is unique in head and neck sites. Further, the genetic profile of mucosal melanomas is different from that of most cutaneous tumors. Thus, within the head and neck region, mucosal melanoma is a distinct entity for which a dedicated data set was developed for implementation. The elements that comprise the core (required) and noncore (recommended) elements are discussed.

NY-ESO-1 Based Immunotherapy of Cancer: Current Perspectives

NY-ESO-1 or New York esophageal squamous cell carcinoma 1 is a well-known cancer-testis antigen (CTAs) with re-expression in numerous cancer types. Its ability to elicit spontaneous humoral and cellular immune responses, together with its restricted expression pattern, have rendered it a good candidate target for cancer immunotherapy. In this review, we provide background information on NY-ESO-1 expression and function in normal and cancerous tissues. Furthermore, NY-ESO-1-specific immune responses have been observed in various cancer types; however, their utility as biomarkers are not well determined. Finally, we describe the immune-based therapeutic options targeting NY-ESO-1 that are currently in clinical trial. We will highlight the recent advancements made in NY-ESO-1 cancer vaccines, adoptive T cell therapy, and combinatorial treatment with checkpoint inhibitors and will discuss the current trends for future NY-ESO-1 based immunotherapy. Cancer treatment has been revolutionized over the last few decades with immunotherapy emerging at the forefront. Immune-based interventions have shown promising results, providing a new treatment avenue for durable clinical responses in various cancer types. The majority of successful immunotherapy studies have been reported in liquid cancers, whereas these approaches have met many challenges in solid cancers. Effective immunotherapy in solid cancers is hampered by the complex, dynamic tumor microenvironment that modulates the extent and phenotype of the antitumor immune response. Furthermore, many solid tumor-associated antigens are not private but can be found in normal somatic tissues, resulting in minor to detrimental off-target toxicities. Therefore, there is an ongoing effort to identify tumor-specific antigens to target using various immune-based modalities. CTAs are considered good candidate targets for immunotherapy as they are characterized by a restricted expression in normal somatic tissues concomitant with a re-expression in solid epithelial cancers. Moreover, several CTAs have been found to induce a spontaneous immune response, NY-ESO-1 being the most immunogenic among the family members. Hence, this review will focus on NY-ESO-1 and discuss the past and current NY-ESO-1 targeted immunotherapeutic strategies.

Desmoplastic melanoma of the oral cavity: diagnostic pitfalls and clinical characteristics

Objectives

Desmoplastic melanoma of the oral cavity is an extremely rare condition that is often confused on initial diagnosis with non-melanotic benign lesion or spindle cell tumors. The purpose of this article was to raise awareness of the disease using a literature review.

Materials and Methods

We analyzed 19 desmoplastic melanoma cases reported in the literature and added our experience. Data on clinical, histopathology, treatment, and survival were retrieved and analyzed. Survival analysis was by the Kaplan-Meier method.

Results

Initial clinical and histopathological features were indistinctive, and a definite diagnosis of desmoplastic melanoma at initial assessment was possible in only 23.5% of cases. Among tests, immunohistochemical studies for S-100 and vimentin were all positive. The 5-year disease-free survival rate for oral desmoplastic melanoma was 0%, and the 5-year overall survival rate was 55.0%.

Conclusion

Oral desmoplastic melanoma has a high percentage of initial misdiagnosis and propensity for local recurrence. Thus, careful initial diagnosis and adequate surgery may result in improved overall survival.

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.

Clinical investigation of 38 cases of oral mucosal melanoma: A multicentre retrospective analysis in Japan

BACKGROUND/OBJECTIVES

The aim of the present study was to investigate treatment modalities and outcomes in oral mucosal melanoma.

METHODS

The clinical and pathological data of 38 consecutive patients with oral mucosal melanoma were retrospectively analyzed. Patients' characteristics were analyzed and overall survival (OS) rates were calculated.

RESULTS

Sixteen patients had stage III (42%), 19 IVA (50%), and three had stage IVC (8%) disease. Among the therapeutic approaches used, 31 patients (82%) received radical therapy (surgery +/- chemotherapy). The 5-year OS rate was 40%. Five-year OS rates according to the clinical stage were 71% for stage III, 24% for stage IVA, and 0% for stage IVC. Five-year OS rates according to therapeutic approaches were 52% in the radical therapy group and 0% in the palliative therapy and best supportive care groups.

CONCLUSIONS

The results of this multicentre retrospective analysis of patients with oral mucosal melanoma suggest that radical therapy based on surgical treatments with complete surgical excision with clear margins leads to a better prognosis.

Primary mucosal melanoma of the oral cavity: current therapy and future directions

BACKGROUND

Primary mucosal melanoma of the oral cavity is a highly aggressive malignancy of melanocytic origin. The aim of this study is to report a case series of oral mucosal melanomas (OMMs) and provide a review of the literature with regard to treatment guidelines for and prognosis of this pathologic entity.

STUDY DESIGN

We report three cases of OMMs treated in our institutions and the results of a literature review, in which the words "oral" and "mucosal melanoma" were used as the main keywords.

RESULTS

Surgical resection of the primary tumor with wide resection margins appears to be the recommended primary treatment modality with the aim to achieve tumor-free margins. Elective neck dissection and adjuvant radiotherapy have been advocated for locoregional control. Chemotherapy has not been shown to improve survival and is mainly used for palliative purposes. Immunotherapy and biochemotherapy seem to significantly improve survival and could open new therapeutic horizons.

CONCLUSIONS

The prognosis of OMMs remains poor despite treatment. Early diagnosis and aggressive surgical resection followed by adjuvant therapies could be the key to improving survival. Multicenter randomized clinical trials, which may be difficult to conduct because of the rarity to the lesion, would aid in the development of new strategies.

Primary amelanotic mucosal melanoma of the oronasal region: report of two new cases and literature review

Primary amelanotic mucosal melanoma is a rare entity with challenging histopathological features. Because these tumors are thought to be biologically more aggressive, they have a poorer prognosis than that of pigmented melanomas. In this work, we present a literature review about the clinical, histopathological, and immunohistochemical features of primary amelanotic mucosal melanoma of the oronasal region and report two new cases. Amelanotic mucosal melanoma commonly affects men in the seventh decade of life and tend to have a poor prognosis, as seen by the high incidence of metastasis, recurrences, and, ultimately, death. There is a similar pattern in the clinic-pathological predilections (such as age, gender, primary site, and metastatic potential) of amelanotic mucosal melanoma when comparing with data reported for pigmented lesions. This work reinforces knowledge about amelanotic mucosal melanomas and epidemiologic predilections. The optimal management of this lesion remains controversial.

Gastric metastases from invasive primary mucosal epithelioid malignant melanoma of the hard palate: report of the first case in the English literature

Melanocytes arise from the neural crest and migrate to the epidermis, meninges, uveal tract and ectodermal mucosa. Normal gastric mucosa lacks melanocytes. A 64-year-old woman presented to us with nausea and vomiting. She had a past history of invasive primary mucosal epithelioid malignant melanoma of the hard palate 21 months ago, treated by a wide surgical excision. Gastroscopy revealed multiple punched out ulcers involving the stomach and the first part of duodenum. Immunohistology and clinicopathologic correlation established the diagnosis of metastatic gastric malignant melanoma. To our knowledge, this is the first report in the English literature about gastric metastases arising from primary palatal mucosal melanoma.

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.

Oral desmoplastic melanoma mimicking inflammatory hyperplasia

INTRODUCTION

Desmoplastic melanoma (DM) arising in the oral cavity is a rare neoplasm that may be confused with a variety of non-melanocytic benign or malignant lesions.

OBJECTIVES

To present a case of DM in the oral mucosa mimicking fibrous inflammatory hyperplasia, discusses the difficulties involved in the diagnosis and offers a literature review on the clinicopathologic and immunohistochemincal aspects of this neoplasm.

CASE REPORT

A 62-year-old white male, smoker, was referred with a chief complaint of pain and swelling in the palate. The oral examination revealed multiple brown-to-black patches and a non-pigmented sessile nodule located on the mucosa of the hard palate. The clinical diagnosis of the pigmented lesions was either oral melanosis or melanoma. The nodular lesion was clinically diagnosed as fibrous inflammatory hyperplasia. Incisional biopsy was performed on the pigmented lesion and the microscopic sections revealed a melanotic macule. The nodular lesions histologically revealed an amelanotic desmoplastic melanoma.

CONCLUSIONS

Reactive lesions close to a pigmented area should be investigated with great care.

Primary mucosal desmoplastic melanoma of the nasal vestibule: the second case

Primary mucosal desmoplastic melanoma is an exceedingly rare, potentially devastating disease that is often initially misdiagnosed because of its deceptively benign presentation. We report what we believe is only the second case of mucosal desmoplastic melanoma arising from the nasal vestibule. The patient, a 62-year-old woman, presented with an obstructive, enlarging mass in the nasal cavity. The tumor, which was initially believed to be benign, was excised, but it recurred 12 months postoperatively. The recurrence was excised, but 4 years later, the patient experienced a second recurrence; in this case, the tumor had invaded the cribriform plate and extended to the anterior cranial fossa. The tumor subsequently metastasized to the dura mater, which led to the patient's death. We review the distinction between conventional mucosal melanoma and mucosal desmoplastic melanoma, and we discuss the ways in which the behavior of a desmoplastic melanoma can point to the diagnosis. Because a diagnosis can be difficult to establish, we stress the importance of maintaining a high index of suspicion when evaluating pathologic and immunohistochemical findings in a patient with a recurrent mucosal nasal mass.

Prognostic significance of regulators of cell cycle and apoptosis, p16(INK4a), p53, and bcl-2 in primary mucosal melanomas of the head and neck

Abnormalities in cell cycle regulation, tumor suppressor gene functions and apoptosis are frequent events in tumorigenesis. Their role in the pathogenesis and prognosis of primary mucosal melanomas (MM) of the upper aerodigestive tract remains unknown. Sixty-four patients (40 men, 24 women, median age 64 years) with MM were included in this study; 32 had tumors in the nasal/paranasal cavities, 28 in the oral cavity and 4 in the pharynx. Archival tissues from 47 initial mucosal tumors, 17 mucosal recurrences, and 13 nodal/distant metastases were subjected to immunohistochemistry using antibodies against p16, p53, and bcl-2. The results were correlated with histological features and survival data. Expressions of p16, p53, and bcl-2 proteins were seen in 25% (N=19/76), 21% (N=16/76), and 74% (N=56/76) of all tumors, respectively. bcl-2 expression in the initial tumors was associated with significantly longer overall and disease specific survival (3.3 vs. 1.5 years, P ≤ 0.05). Expression of p16 was increasingly lost, from 32% in initial tumors to 12% in recurrent and 15% in metastatic tumors (P=0.06). Tumors comprised of undifferentiated cells were significantly more p53 positive than epithelioid or spindle cells (80% vs. 33%, P=0.02). Expression of these markers did not correlate with necrosis, or vascular and/or deep tissue invasion. Expression of bcl-2 is associated with better survival in MM. Loss of p16 was seen with tumor progression whereas aberrant p53 expression was frequent in undifferentiated tumor cells.

Incidence and survival of desmoplastic melanoma in the United States, 1992-2007

BACKGROUND

Desmoplastic melanoma (DM) represents a relatively rare malignancy. The aim of this study was to describe the incidence and survival of DM in the United States.

METHODS

Incidence and survival data were obtained from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program, 1992-2007. Kaplan-Meier and Cox proportional hazards regression methods were used to calculate the survival rates and hazard ratios for DM-specific death.

RESULTS

We identified 1129 DM patients from SEER 13 registries, with 64% in men, 37% in women and most (96.8%) occurring in White populations. The incidence rates per 1,000,000 were 1.3 (female), 3.0 (male) and 2.0 (both). The annual percentage change for incidence was 4.6 (95% confidence interval: 2.9-6.5) from 1992 to 2007. The 5-year and 10-year DM-specific survival rates from SEER 17 registries were 84.8 and 79.2%. The 5-year DM-specific survival rates by stage ranged from 90.9% (local) to 51.5% (distant). Independent predictors of mortality from DM included age, anatomic site, thickness, ulceration, lymph node and surgery.

CONCLUSIONS

The incidence of DM has been increasing steadily over the past 15 years. Older age, anatomic site of the head and neck, tumor thickness >2 mm, ulceration, lymph node involvement and non-receipt of surgery are associated with lower survival.

Pigmented lesions of the oral mucosa and perioral tissues: a flow-chart for the diagnosis and some recommendations for the management

The term "pigmentation of the oral mucosa" is applied to a wide range of lesions or conditions featuring a change of color of oral tissues. Lesions not associated with an accumulation of pigment (e.g., Fordyce spots) are usually not classified as pigmented lesions. Two groups of pigmented lesions of the oral mucosa are recognized: 1) melanin-associated lesions, including racial pigmentations, melanotic macules, melanocytic nevi, and malignant melanoma; and 2) nonmelanin-associated lesions (e.g., blood-related pigmentations, metallic pigmentations). This paper presents a clinicopathologic review of the recent literature with emphasis on the main diagnostic features, including the use of immunohistochemical markers. A flow-chart is added that may help the clinician in the diagnosis and management of these lesions.

What is the role of radiotherapy in the treatment of mucosal melanoma of the head and neck?

Mucosal melanoma of the head and neck is a rare, poor prognosis tumour with a high tendency to recur locally and regionally after surgical resection. A number of centres have used radiotherapy to sterilize positive and close margins after non-radical surgery or to treat inoperable cases. The present article discusses the literature data to analyze the possible indications for radiotherapy in terms of patient selection and treatment strategy. In the majority of the available retrospective series, postoperative radiotherapy improves the local control of mucosal melanomas, but its effect on survival has not yet been sufficiently investigated. Radiobiological studies show a high heterogeneity in behaviour of irradiated melanoma cells and the clinical implications of this will be illustrated. In the future, a better understanding of the radiosensitivity of this rare tumour and the availability of new technical modalities might allow for a more profitable incorporation of radiotherapy into a multidisciplinary strategy.

Malignant melanoma in the 21st century, part 1: epidemiology, risk factors, screening, prevention, and diagnosis

Malignant melanoma is an aggressive, therapy-resistant malignancy of melanocytes. The incidence of melanoma has been steadily increasing worldwide, resulting in an increasing public health problem. Exposure to solar UV radiation, fair skin, dysplastic nevi syndrome, and a family history of melanoma are major risk factors for melanoma development. The interactions between genetic and environmental risk factors that promote melanomagenesis are currently the subject of ongoing research. Avoidance of UV radiation and surveillance of high-risk patients have the potential to reduce the population burden of melanoma. Biopsies of the primary tumor and sampling of draining lymph nodes are required for optimal diagnosis and staging. Several clinically relevant pathologic subtypes have been identified and need to be recognized. Therapy for early disease is predominantly surgical, with a minor benefit noted with the use of adjuvant therapy. Management of systemic melanoma is a challenge because of a paucity of active treatment modalities. In the first part of this 2-part review, we discuss epidemiology, risk factors, screening, prevention, and diagnosis of malignant melanoma. Part 2 (which will appear in the April 2007 issue) will review melanoma staging, prognosis, and treatment.

Oral malignant melanoma: A review of the literature

Primary oral malignant melanoma (OMM) is a rare neoplasm, accounting for 0.5% of all oral malignancies. The etiology is unknown; tobacco use and chronic irritation may play some role. Clinically, OMM may mimick other pigmented lesions. A biopsy is required in order to establish the diagnosis. The reported risk of malignant cells spreading during invasive procedures and factors such as size of the lesion or anatomical limitations, may influence the diagnostic surgical procedure. Therapy of OMM is commonly based on surgical excision of the primary tumour, supplemented by radiotherapy, with chemotherapy and immunotherapy serving as adjuncts. Prognosis is poor, with a 5-year survival rate of approximately 15%.

Head and Neck Mucosal Melanoma

PURPOSE

The purpose of this article is to discuss the optimal treatment and outcomes for head and neck mucosal melanoma.

METHODS

Review the pertinent literature.

RESULTS

Head and neck mucosal melanoma is a rare entity comprising less than 1% for all Western melanomas. It usually arises in the nasal cavity, paranasal sinuses, and oral cavity. The optimal treatment is surgery. The likelihood of local recurrence after resection is approximately 50%. Radiotherapy (RT) reduces the likelihood of local failure but probably does not enhance survival, which is primarily impacted by advanced T stage and the presence of regional metastases. The 5-year survival rates vary from approximately 20 to 50%. Although the median time to relapse is roughly 1 year or less, late failures are common and cause-specific survival continues to decline after 5 years.

CONCLUSION

The optimal treatment is surgery. Postoperative RT improves local-regional control but may not impact survival. Definitive RT may occasionally cure patients with unresectable local-regional disease or at least provide long-term palliation.

Desmoplastic melanoma: a pathologically and clinically distinct form of cutaneous melanoma

BACKGROUND

Desmoplastic melanoma (DM) is a rare variant characterized by the presence of fusiform melanocytes in a sclerotic stroma. Pathologic heterogeneity within DM may account for the controversy regarding the clinical presentation and prognosis of DM compared with conventional melanoma (CM).

METHODS

We identified 131 patients with a diagnosis of DM seen between 1979 and 2002. Tumors were categorized as either pure DM (pDM; n = 92), if desmoplasia was prominent throughout the entire invasive tumor, or mixed DM (mDM; n = 39), if fibrosis was well developed in only parts of an otherwise non-DM. Differences in clinical behavior among pDM, mDM, and CM (n = 3976) were examined.

RESULTS

Seventy-three percent of patients with DM had tumors >2 mm in depth, compared with 31% of patients with CM (P < .001). Regional nodal metastasis was uncommon in patients who presented with clinically localized pDM (1%) compared with those with mDM (10%) or CM (6%) (P < .05, pDM vs. CM). Five-year melanoma-specific mortality was lower for patients who presented with pDM compared with mDM (11% vs. 31%; P < .01). Patients with pDM and CM had a similar melanoma-specific mortality despite a 3-fold difference in median tumor depth (3.6 vs. 1.2 mm, respectively).

CONCLUSIONS

DMs can be divided into two subtypes based on a histological quantification of desmoplasia. Tumors with prominent fibrosis (pure subtype) are unlikely to disseminate to regional lymph nodes and are associated with a favorable outcome when compared with those with mixed desmoplasia or CM.

Desmoplastic melanoma: a diagnostic trap for the unwary

Desmoplastic melanoma (DM) is an uncommon type of spindle cell melanoma in which the malignant cells are separated by collagen fibres or fibrous stroma. DM is prone to misdiagnosis because of unfamiliarity with its often bland appearance and dissimilarity to other conventional types of melanoma. It displays variable cytological atypia, cellularity and stromal fibrosis and more often than not has an accompanying atypical junctional component. Neurotropism is a common associated feature (in at least 30% of cases) and when it occurs such tumours are termed 'desmoplastic neurotropic melanomas' (DNM). The neurotropism may be perineural or intraneural and often extends beyond the desmoplastic component. In addition, some DMs show evidence of neural differentiation ('neural transformation'). DM may also present as a recurrence or occasionally as a metastasis from other types of melanoma. A high index of suspicion and knowledge of its often subtle morphological appearance are necessary to avoid misdiagnosis.