Desmoplastic malignant melanoma of the oral mucosa. An underrecognized diagnostic pitfall

Early Stage Melanoma of the Vermillion with Mucosal Melanoma in Situ: A Clinical Conundrum

BACKGROUND

Melanoma is a predominantly cutaneous malignancy associated with sun exposure. Mucosal melanoma is rare and carries a distinct pathogenesis from cutaneous tumors. The vermillion of the lip is a unique site that divides cutaneous from mucosal tissues. Tumors arising on the dry aspect are classified as cutaneous and those of the wet aspect are mucosal. The distinction is importation in tumor staging as all mucosal melanomas are classified as T3-T4b under the current 8th edition American Joint Committee of Cancer (AJCC) guidelines.

METHODS

We describe a case of early stage melanoma of the vermillion with associated mucosal melanoma in situ. We discuss nuances of management at this site and the distinctions between cutaneous versus mucosal melanomas with a review of the literature.

RESULTS

Our patient was treated surgically with 2-3 cm margins. Residual melanoma in situ was present at the mucosal margin on final pathology which required a second surgery for margin revision. The case was discussed at tumor board with recommendation for no further treatment.

CONCLUSIONS

The nuances between the vermillion and mucosal lip must be understood for appropriate staging and treatment of melanomas. The paucity of literature on melanomas affecting this site render management decisions challenging. Multidisciplinary discussion is essential for guiding care.

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.

Lower Extremity Desmoplastic Malignant Melanoma in Egypt

Desmoplastic melanoma (DM) is a type of spindle cell melanoma characterized by the absence of pigment. The clinical diagnosis of DM represents a challenge for the practitioner and the pathologists because it can mimic benign or malignant skin tumors and even inflammatory skin disorders. We here discuss a case of a patient presented with multiple nodular lesions of the lower extremity following electrocautary to a lesion in her sole which was misdiagnosed as planter wart. Our clinical diagnosis was Kaposi sarcoma, hypertrophic lichen, or extensive verruca vulgaris. However, histopathological examination showed spindle-shaped cells positive for Melan-A and S100 revealing the diagnosis of DM.

A rare case of amelanotic malignant melanoma in the oral region: Clinical investigation and immunohistochemical study

Amelanotic malignant melanoma (AMM) is rare in the oral region. The present study examined the clinical features of this tumor in an attempt to establish diagnostic criteria. The expression of three melanocytic differentiation markers, HMB-45, S-100 and Melan-A, was also measured in primary oral AMMs in order to determine whether the markers could be used to diagnose primary oral AMMs and to find out which marker was the most sensitive. It may be particularly difficult to correctly diagnose AMM that lacks a radial growth phase without immunohistochemical assistance. In the present study, mixtures of polygonal and spindle cells at different ratios were observed in the tumors with and without a radial growth phase. Immunohistochemistry was used to examine the HMB-45, S-100 and Melan-A expression in the formalin-fixed paraffin-embedded specimens of primary oral AMMs. Comparison of staining intensities (SIs) and labeling indices (LIs) of the markers was also performed. The immunostaining results revealed that the SI of Melan-A was significantly higher than that of S-100 (P=0.0011). HMB-45, S-100 and Melan-A also exhibited high positive rates and LIs in AMMs and, therefore, may be good markers for the immunohistochemical diagnosis of primary oral AMMs. Furthermore, Melan-A may be a more sensitive marker than S-100 and HMB-45, as it has a higher SI.

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.

Desmoplastic melanoma

Desmoplastic melanoma (DM) is a variant of spindle cell melanoma characterized by the presence of abundant fibrous matrix. It is typically found in the head and neck region on chronically sun-damaged skin of older individuals. Early detection is uncommon, because its clinical features are not distinctive. DM is prone to misdiagnosis not only clinically but also histologically. It may simulate a sclerosing melanocytic nevus and various benign and malignant nonmelanocytic lesions. Among melanomas said to be desmoplastic by various pathologists there is significant variation with regard to the extent of intratumoral fibrosis. It may be prominent throughout the entire tumor (pure DM) or represent a portion of an otherwise nondesmoplastic melanoma (combined DM). Immunophenotypically, DM are usually strongly and homogeneously positive for S-100 protein, but are often negative or only focally positive for melanocyte differentiation antigens. DM differs from conventional melanoma in its clinical course. It is associated with a higher tendency for local recurrence, but metastases to regional lymph nodes are less common.

Prognostic factors in cutaneous desmoplastic melanoma: a study of 252 patients

BACKGROUND

Desmoplastic melanoma (DM) is a rare subtype of melanoma that is characterized by malignant spindle cells separated by prominent, fibrocollagenous stroma. Primary melanomas either may be entirely desmoplastic or almost entirely desmoplastic (pure DM [pDM]) or may exhibit a desmoplastic component admixed with a nondesmoplastic component (combined DM [cDM]).

METHODS

Patients who were diagnosed between 1993 and 2007 at a single institution with clinically localized, primary cutaneous melanoma (PCM) that contained a desmoplastic component and who underwent sentinel lymph node (SLN) biopsy were identified. Clinical and pathologic features of the primary tumors were correlated with DM type, SLN status, and patient outcome.

RESULTS

Two hundred fifty-two patients (167 men, 85 women) were identified (median age, 61 years). The median tumor thickness was 2.0 mm. One hundred twenty-three patients (48.8%) had pDM, and 129 patients (51.2%) had cDM. Overall, 17 patients (6.7%) had positive SLN status, including 12 patients with cDM and 5 patients with pDM. Because of the low SLN-positive rate, a statistically significant difference in SLN status between patients with cDM (8.5%) and patients with pDM (4.9%; P = .25) could not be demonstrated. Older patient age, being a man, positive SLN status, and increasing tumor thickness were associated significantly with poorer disease-free survival (P < .05), although only the latter 2 variables were independently predictive. In addition, cDM type (P = .017) was associated significantly and independently with a shorter time to recurrence.

CONCLUSIONS

In this largest study to date of patients with DM who underwent SLN biopsy, the SLN-positive rate in patients with DM was lower than that in patients with conventional melanoma. The results indicated that DM type is associated significantly and independently with the time to recurrence and should be evaluated routinely in all patients with PCM. Cancer 2010. (c) 2010 American Cancer Society.

Desmoplastic Melanoma

Desmoplastic melanoma (DM) is a variant of spindle cell melanoma characterized by the presence of abundant fibrous matrix. It is typically found in the head and neck region on chronically sun-damaged skin of older individuals. Early detection is uncommon, because its clinical features are not distinctive. DM is prone to misdiagnosis not only clinically but also histologically. It may simulate a sclerosing melanocytic nevus and various benign and malignant nonmelanocytic lesions. Among melanomas said to be desmoplastic by various pathologists there is significant variation with regard to the extent of intratumoral fibrosis. It may be prominent throughout the entire tumor (pure DM) or represent a portion of an otherwise nondesmoplastic melanoma (combined DM). Immunophenotypically, DM are usually strongly and homogeneously positive for S-100 protein, but are often negative or only focally positive for melanocyte differentiation antigens. DM differs from conventional melanoma in its clinical course. It is associated with a higher tendency for local recurrence, but metastases to regional lymph nodes are less common.

Mucosal melanoma of the head and neck

OBJECTIVE

Outcomes after radiotherapy for head and neck mucosal melanoma (MMHN).

METHODS

From 1974 to 2005, 17 patients with primary MMHN were treated with radiotherapy. Primary sites included nasal cavity, paranasal sinuses, and oral cavity or oropharynx. Thirteen patients received surgery and postoperative radiotherapy; 4 received definitive radiotherapy.

RESULTS

Local control was 79% at 1 and 5 years for 13 of 13 patients treated with surgery and postoperative radiotherapy compared with 1 of 4 patients treated with definitive radiotherapy. Three patients recurred in the neck; 13 patients developed distant metastases. Disease-free survival was 23% at 1 year and 18% at 5 years. Absolute and cause-specific survivals were identical (53% and 28% at 1 and 5 years).

CONCLUSION

Locoregional control is relatively high after surgery and adjuvant radiotherapy, but most patients recur in distant sites; approximately one fourth of patients are cured at 5 years. Patients with unresectable tumor may be controlled with definitive radiotherapy.

Selected Diagnostic Problems in Neoplastic Dermatopathology

Context.—Selected cutaneous neoplasms share features with benign counterparts or have subtle morphologic features that could be overlooked by the pathologist.

Objective.—To present clues to the diagnosis of potentially deceptive malignancies, including desmoplastic malignant melanoma, nevoid malignant melanoma, subcutaneous lymphoma, metastatic breast carcinoma, and epithelioid sarcoma.

Data Sources.—Published literature and personal experience.

Conclusions.—Knowledge of commonly misdiagnosed cutaneous neoplasms will help the general surgical pathologist avoid these potential pitfalls in neoplastic dermatopathology.

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.

HMB-45 may be a more sensitive maker than S-100 or Melan-A for immunohistochemical diagnosis of primary oral and nasal mucosal melanomas

BACKGROUND

Primary mucosal melanomas (MMs) of the head and neck are a rare entity. Melanomas with characteristic melanin-pigmented tumor cells are easy to diagnose, but those without melanin-pigmented tumor cells, amelanotic melanomas, are difficult to identify and need immunohistochemistry (IHC) to confirm the final diagnosis. In this study, we examined the expression of three melanocytic differentiation markers, HMB-45, S-100, and Melan-A in primary oral and nasal MMs. We tried to evaluate whether HMB-45, S-100, and Melan-A were useful for diagnosis of primary oral and nasal MMs and to find out which marker was the best of the three.

METHODS

This study used IHC to examine the expression of HMB-45, S-100, and Melan-A in 17 formalin-fixed paraffin-embedded specimens of primary oral and nasal MMs. The staining intensities (SIs) and labeling indices (LIs) of HMB-45, S-100, and Melan-A in 17 MMs were calculated and compared between any two markers.

RESULTS

Immunostaining results showed that the positive rate was 94% (16 of 17) for HMB-45, 88% (15 of 17) for S-100, and 71% (12 of 17) for Melan-A in 17 MMs. The SI of HMB-45 was significantly higher than that of S-100 (P = 0.0011) or of Melan-A (P = 0.0034). In addition, the mean LI of Melan-A (59 +/- 43%) was significantly lower than that of HMB-45 (83 +/- 28%, P = 0.0065) or of S-100 (79 +/- 33%, P = 0.0237).

CONCLUSIONS

Our results indicate that both HMB-45 and S-100 show a high positive rate and LI in MMs and therefore may be good markers for immunohistochemical diagnosis of primary oral and nasal MMs. In addition, HMB-45 may be a more sensitive marker than S-100 because HMB-45 shows a significantly higher SI than S-100 in this study.

Cutaneous desmoplastic melanoma: reappraisal of morphologic heterogeneity and prognostic factors

Desmoplastic melanoma (DM) is a variant of melanoma, which may be confused with nonmelanocytic benign or malignant spindle cell proliferations. The histologic hallmark of DM is the presence of fusiform melanocytes dispersed in a prominent collagenous stroma. Phenotypic heterogeneity of DM is underrecognized. Desmoplasia may be prominent throughout the entire tumor ("pure" DM) or represent a portion of an otherwise nondesmoplastic melanoma ("combined" DM). We reviewed melanomas with desmoplasia from 92 patients seen at a single institution between 1980 and 2002. Fifty-five of the tumors were pure DM. Thirty-seven were classified as combined. Mean follow-up of patients was 46 months for those alive at the last follow-up. Univariate analysis of clinical and pathologic parameters revealed four significant variables for disease-free survival: Clark level (IV vs. V; P = 0.005), DM subtype (pure vs. combined; P = 0.01), tumor mitotic rate (<1, 1-4, >4 mitoses/mm; P = 0.01), and tumor thickness (<1 mm, 1-4 mm, >4 mm; P = 0.02). Only histologic subtype (P = 0.02) and Clark level (P = 0.05) were independently significant by Cox regression analysis. Our results indicate that distinguishing pure from combined forms of DM is clinically relevant for prognosis (pure forms being associated with longer disease-specific survival). Failure to make this distinction may account for conflicting reports in the literature on the biologic behavior and prognosis of DM.

Cutaneous desmoplastic melanoma

Desmoplastic melanoma (DM) is a fibrosing variant of spindle cell melanoma. It most often presents as an indurated lesion in chronically sun-damaged skin. Due to the lack of characteristic clinical features, early detection is uncommon. At the time of excision, the tumors usually extend into the reticular dermis or deeper. DM is prone to misdiagnosis. It may simulate histologically sclerosing melanocytic nevi as well as various benign and malignant nonmelanocytic lesions. There is significant morphologic variability among tumors classified as DM. Desmoplasia may be prominent throughout the entire tumor ("pure" DM) or represent a portion of an otherwise nondesmoplastic melanoma ("combined" DM). Some tumors show neuroma-like features with prominent nerve involvement, in which case the term "desmoplastic neurotropic melanoma" is used. Immunophenotypically, DMs are usually strongly and homogeneously positive for S-100 protein but are often negative or only focally positive for melanocyte differentiation antigens such as tyrosinase, gp100, Melan-A, and microphthalmia transcription factor. DM differs from conventional melanoma in its clinical course. It is associated with a higher tendency for local recurrence, but metastases to regional lymph nodes are less common. Evidence is also emerging that for patients with thick melanomas, the presence of a paucicellular fibrosing tumor histology (pure DM) is a favorable prognostic factor for survival.

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.

Pigmented lesions in unusual anatomic sites

This review considers pigmented melanin-containing lesions arising in extracutaneous locations. It includes reactive lesions as well as benign and malignant neoplasms. Melanocytic lesions of the mucosae, nervous system, and individual organs are discussed, and rarer pigmented tumors in unusual sites are also covered. A brief description of the histology and clinical behavior along with proposed explanations for their ectopic location are provided. Emphasis is given to the reality that detailed morphological evaluation and application of ancillary techniques can establish the melanocytic nature and biologic potential of such tumors, but cannot, by themselves, determine the primary or metastatic nature of these lesions.

Primary mucosal desmoplastic melanoma of the head and neck

BACKGROUND

Desmoplastic variants of melanoma rarely affect the mucosa.

METHOD

The clinicopathologic features and p53 status of seven primary mucosal desmoplastic melanomas of the oral and nasal cavity were studied.

RESULTS

The patients included six men and one woman (median age, 61 years; range, 23-74 years). Desmoplastic melanoma involved the lip in two, alveolus in three, buccal mucosa in one, and nasal vestibule in one patient. Four tumors infiltrated up to lamina propria, and three infiltrated bone and/or cartilage. All were amelanotic spindle cell tumors, five were neurotropic, and two were vasoinvasive. Aberrant p53 expression was seen in six tumors. All tumors recurred locally, and distant metastasis developed in three. Six patients died with disease (survival, 1-41 years; median, 8 years), and one patient was free of disease (survival 20 years).

CONCLUSIONS

Primary mucosal desmoplastic melanomas are clinically characterized by local recurrence and may lead to distant metastasis and death even after several years. Alterations in p53 expression are frequently associated with desmoplastic melanoma.

Efficacy of radiation therapy in the local control of desmoplastic malignant melanoma

BACKGROUND

Desmoplastic malignant melanoma (DMM) is a rare variant of malignant melanoma with high local recurrence rate after surgical excision. We performed a retrospective review to address the role of radiation therapy in local control of this tumor.

METHODS

Between 1976 and 1997, 44 patients with the pathologic diagnosis of DMM were registered at our tumor registry. Fourteen patients received postoperative RT, and one patient received preoperative RT. Three of the irradiated lesions had gross residual or positive surgical margins. Doses ranged from 44 to 66 Gy.

RESULTS

Sixty-eight percent of DMM lesions occurred in the head and neck region. Forty-eight percent (21 of 44) of patients experienced a local recurrence after initial excision (mean time to recurrence, 12 months). Local failure in head and neck was 46% (14 of 30). Clark level, primary site, and neurotropism did not predict local recurrence; the Clark level predicted distant metastasis. No viable tumor was found in the surgical specimen of the patient who received preoperative RT. None of 15 patients who received adjuvant irradiation had any additional recurrences (mean follow-up, 64.7 months). By contrast, four of seven patients with history of recurrence who did not receive RT had local relapse (p =.005). The incidence of distant metastasis did not reach statistical significance between the irradiated and nonirradiated groups.

CONCLUSIONS

The high rate of local recurrence of DMM after surgical resection is dramatically reduced by adjuvant radiation therapy. We recommend adjuvant postoperative radiation therapy as a part of treatment of DMM.

Expression of melanocytic differentiation markers in malignant melanomas of the oral and sinonasal mucosa

Malignant melanomas of the oral and sinonasal mucosa are rare tumors. Amelanotic variants can, on occasion, be difficult to recognize by routine light microscopy. Immunohistochemical studies may be needed for a final diagnosis. A number of new monoclonal antibodies to melanocytic differentiation antigens have been studied recently on primary cutaneous and metastatic melanoma. However, little is known about these antibodies for the diagnosis of mucosal melanomas. In this study the authors analyzed 79 oral and sinonasal mucosal melanomas of 65 patients. A total of 35 tumors originated from the oral mucosa (21 primary tumors, eight local recurrences, and six metastases) and 44 melanomas were from the sinonasal tract (27 primary tumors, nine local recurrences, and eight metastases). Immunohistochemical studies were performed on paraffin-embedded tissues, using the following antibodies: anti-S-100 protein, T311 (anti-tyrosinase), A103 (anti-Mart-1/Melan-A), D5 (antimicrophthalmia-associated transcription factor), and HMB-45 (anti-gp100). Of 35 oral mucosal tumors, 34 (97%) were positive with anti-S-100 protein, 33 (94%) with T311, 30 (85%) with A103, 26 (74%) with D5, and 25 (71%) with HMB-45. All five desmoplastic melanomas of the oral mucosa were positive for S-100 protein, four for tyrosinase, and one each for HMB-45 and A103. No desmoplastic melanoma was positive with D5. All 44 sinonasal melanomas were positive for tyrosinase and Mart-1/Melan-A (100%). Forty-three (98%) were positive with HMB-45, 42 (95%) with anti-S-100 protein, and 40 (91%) with D5. These results reveal that T311 is the most sensitive marker for sinonasal melanomas and closely approaches the sensitivity of anti-S-100 protein for oral mucosal melanomas. For desmoplastic mucosal tumors, anti-S-100 protein remains the most sensitive marker.

Analysis of microphthalmia transcription factor expression in normal tissues and tumors, and comparison of its expression with S-100 protein, gp100, and tyrosinase in desmoplastic malignant melanoma

Microphthalmia transcription factor (Mitf) is a nuclear protein involved in the development of melanocytes and the regulation of melanin synthesis. Recent studies have suggested that Mitf may be a more sensitive and specific melanocyte marker than S-100 protein and gp100. However, there is insufficient knowledge on the specificity of Mitf, and a systematic examination of its use for the recognition of desmoplastic melanoma has not yet been performed. In this study, we compared the expression of Mitf with S-100 protein, gp100, and tyrosinase in 20 desmoplastic melanomas by using the antibodies D5 (anti-Mitf), anti-S100P, HMB-45 (anti-gp100), and T311 (anti-tyrosinase). All 20 melanomas were positive for S-100 protein, 7 were positive for Mitf, 6 for gp100, and 11 for tyrosinase. To examine the specificity of Mitf, a panel of normal tissue and 386 samples of miscellaneous tumors, including dermal and subcutaneous spindle cell lesions relevant for the differential diagnosis of desmoplastic melanoma, were examined by immunohistochemistry. Furthermore, normal tissue samples were tested for Mitf mRNA by reverse transcriptase polymerase chain reaction (rt-PCR). Immunoreactivity for Mitf was seen not only in melanocytes of normal skin, but also in macrophages, lymphocytes, fibroblasts, Schwann cells, and smooth muscle cells at various sites, and tumors derived thereof. Our results indicate that the antibody D5 lacks sufficient sensitivity and specificity for widespread diagnostic use. Especially in re-excisions, when immunohistochemistry is often needed to distinguish an inflamed scar tissue from tumor, the presence of immunopositive inflammatory cells and fibroblasts limits the diagnostic use of D5.

Desmoplastic malignant melanoma of the palatal alveolar mucosa: sustained disease-free survival after surgery and postoperative radiotherapy

Aggressive surgical and radiotherapeutic management of a patient with desmoplastic malignant melanoma arising from the mucosa of the oral cavity has resulted in disease-free survival of more than 2(1/2) years after diagnosis. This case represents only the tenth reported instance of desmoplastic malignant melanoma arising from the oral cavity and only the third for which survival has exceeded 2 years. Details of the clinical, histopathologic, and therapeutic features of the case are provided to augment the paucity of literature available to clinicians managing this rare disease.

Recent developments in the pathology of melanocytic neoplasia

This article selectively discusses clinically relevant aspects of the pathology of cutaneous melanocytic neoplasms, from the literature of the past recent years. Topics include the changing role of immunohistochemistry in diagnosis, the controversies over dysplastic nevi, description of other specialized variants of melanocytic nevi, diagnosis of melanocytic neoplasms of acral skin, and melanoma occurring in childhood. Several variants of melanoma including desmoplastic and spindle-cell types, verrucous melanoma, epidermotropic melanoma, and melanoma of the female genitalia are reviewed. The issue of appropriate margins of resection for melanoma and the use of Mohs Micrographic surgery for this tumor are considered. Finally, a review of the sentinel node biopsy technique and of nodal nevi is presented.

Desmoplastic malignant melanoma: diagnosis of early clinical lesions

Desmoplastic malignant melanoma (DMM) is an uncommon but potentially devastating malignancy that can be cured with early recognition and surgery. DMM has clinical as well as histological features that may be subtle and overlooked, or misdiagnosed as other benign or malignant lesions that would require less aggressive therapy for cure. We have reviewed the preliminary clinical diagnoses and histological features of 18 cases of desmoplastic malignant melanoma, defined as either an inapparent lesion clinically, or a papule or small nodule less than 0.7 cm, which proved histologically to be DMM. Nine of 18 cases (50%) were clinically pigmented. Histologically, early lesions were characterized by superficial tumor fascicles, and random diffuse hypercellularity in the upper dermis identified as elongated hyperchromatic pleomorphic spindle cells with stromal myxoid change. Neuroidal melanocytic structures, invasion of adventitial dermis, islands of inflammation, and epidermal lentiginous melanocytic hyperplasia were often present. The most reliable and characteristic features of an early lesion of DMM are aggregates of lymphocytes, tumor cell cytological atypia, stromal myxoid change, and poor circumscription of the dermal infiltrate. DMM is a disease best treated by complete excision at the time of initial surgery, but is also a lesion easily missed or misdiagnosed in the early stages. Features of early DMM are identified and illustrated to enable early diagnosis and cure of these lesions.

Oral melanoma: diagnosis and treatment

Melanoma of the mouth is rare, most commonly occurring on the upper jaw of patients older than 50 years. Because of a frequent delay in diagnosis, the tumors are often diagnosed after they are deeper than the average cutaneous melanoma. Hence, the prognosis tends to be poor. Surgery is the mainstay of treatment, but often it is difficult because of anatomic restraints. Although melanoma is classically not very radiosensitive, occasional patients have had a good response to radiation therapy, sometimes with temporary palliation. Other treatment modalities are similar to those used for cutaneous melanoma. Immunotherapy, including interferon, has been used. Chemotherapy has a low response rate.