Solitary dermal melanoma: beginning or end of the metastatic process?

Characteristics and outcomes of clinical primary dermal melanoma: a case series

Primary dermal melanoma (PDM) is a rare, relatively newly described subtype of melanoma comprising 0.4–0.9% of all melanoma diagnoses. We report nine patients with a clinical diagnosis of PDM.

Primary Dermal Melanoma

Primary dermal melanoma (PDM) is a rare subtype of melanoma with an estimated incidence of less than 1%. PDM presents entirely in the dermis or subcutis and histopathologically mimics cutaneous metastases of melanoma due to its lack of connection to the overlying epidermis. A thorough history and examination, including imaging evaluation for metastatic disease, will reveal no prior history or concurrent lesion of primary cutaneous or metastatic melanoma. Despite its histopathologic similarities to melanoma metastasis, PDM is associated with an unexpectedly favorable prognosis. This review discusses the clinical and histopathologic features of PDM as a distinct subtype of melanoma, as well as the current approach to clinical staging and management.

Metastatic melanoma and rare melanoma variants: a review

The histopathological diagnosis of melanoma is fraught with potential pitfalls. In the setting of cutaneous metastatic melanoma, it is important to recognise the various histological patterns that can be encountered from the more common to the rare, including epidermotropic, folliculotropic, naevoid, and blue naevus-like. In addition, melanoma is notorious for phenotypic plasticity. Thus, there are many different subtypes and cytomorphological variations that can be difficult to recognise as melanoma, particularly in the recurrent or metastatic setting. Select melanoma variants including primary dermal, clear cell, plasmacytoid, signet ring cell, small cell, myxoid, rhabdoid, and dedifferentiated melanoma will be discussed, in addition to composite melanocytic neoplasms. This review is intended to remind the practitioner of key concepts of metastatic disease and select rare melanoma variants, while providing practical guidelines for accurate diagnosis.

Case report of a primary subcutaneous melanoma; a surprising entity for a subcutaneous nodule

INTRODUCTION

A melanoma can originate at the subcutis without any visible skin lesion.

CASE PRESENTATION

A 73-year old patient came to the outpatient clinic with a subcutaneous nodule on the right thigh without any visible lesion of the skin. It turned out to be a primary subcutaneous melanoma that could be classified as a primary dermal melanoma (PDM).

DISCUSSION

A PDM is a very rare subtype of melanoma that stands out for its excellent prognosis in comparison to cutaneous melanomas. No valid reliable staging system or treatment guideline exists for this entity, Breslow depth might overestimate the clinical aggressiveness possibly leading to overtreatment.

CONCLUSION

It is of great importance for the clinician to be familiar with a primary dermal melanoma. It deserves an appropriate place in the current AJCC system and a treatment guideline for this unique melanoma subtype with relativity excellent prognosis would be beneficial.

Primary Dermal Melanoma: A Rare Clinicopathological Variant Mimicking Metastatic Melanoma

Primary dermal melanoma (PDM) is a rare distinct variant of cutaneous melanoma, predominantly occurring on the extremities of young or middle-aged adults. In comparison to conventional melanoma, PDM is characterized by unexpectedly prolonged survival and long-term survival. Thus, correct identification of this variant is crucial to avoid potential misdiagnosis and establish correct treatment and follow-up. In addition, no consensus and specific guidelines exist on the management of this peculiar subtype of cutaneous melanoma.

Primary Dermal Melanoma (PDM): Histological and Clinical Interdependence to Guide Therapy

BACKGROUND/PURPOSE

This study examined clinical and histological parameters of primary dermal melanoma (PDM) to aid in its distinction from dermal metastasis.

METHODS

Retrospective analysis of a prospective cohort of PDM patients. Includes patients fulfilling the strict histologic criteria for PDM (N = 9) and patients who did not, but clinically, unequivocally had an intradermal melanoma-clinical PDM (cPDM; N = 17).Histopathology slides were re-examined. Prognosticators and outcome measures were compared between groups. Sentinel nodes' retrieval and wide local excision (WLE) were offered to all patients as primary treatment.

RESULTS

26 patients identified, 15 females with a median age of 69 years (range 3.5-85). Mean Breslow was 7.9 ± 5.7 mm (median 5.8, range 1.8-25.0), and the mean mitotic rate was 4.9 ± 3.8/mm² (median 4.0, range 0-17). Initial treatment and follow-up were as for cutaneous melanoma. One patient in each group with a palpable stage III underwent primary radical dissection. Sentinel nodes were retrieved in all 20 lymphatic mappings performed and found to be metastatic in 5 (25%) patients. Treatment consisted of completion lymph-node dissection. At a median postoperative follow-up of 62 months (range 8-132), 20 patients were disease-free, including 6 of 7 patients with stage III disease at presentation. Six patients died all of cPDM; 5 of 6 patients had primary ulcerated or epidermal-abutting melanomas.

CONCLUSIONS

This is the first study to highlight cPDM. Diagnosis requires expert pathology review and a tight correlation to the clinical parameters. Patients seem to benefit from WLE with sentinel node retrieval and complete dissection when appropriate. However, clinical guidelines for dissection have changed since the time period of this retrospective review. Based on this series, complete nodal dissection in these melanomas is associated with better than expected outcome, for stage III disease.

Primary dermal melanoma: clinical behaviour, prognosis and treatment

PURPOSE

Primary dermal melanoma (PDM) is a subtype of cutaneous melanoma, confined to the dermis, which poses a challenging clinical dilemma. It may represent a true primary melanoma or a dermal cutaneous metastasis. This study aimed to delineate the histopathological characteristics and prognosis of PDM in a large patient cohort to guide appropriate treatment strategies.

METHODS

A search of the Melanoma Research Database at Melanoma Institute Australia was conducted to identify all possible PDM patients at our institution diagnosed from 1978 to 2013. Overall, melanoma-specific and disease-free survival outcomes of the PDM group were compared to those of similar cohorts of Stage I-II and Stage IV M1a melanoma patients based on propensity score matching.

RESULTS

Sixty-two PDM patients were identified from the MRD with a median follow-up of 6.3 years. Five-year survival was 87.1% and overall survival was 74.2%. PDMs had a significantly improved overall survival (p = 0.0002) and melanoma-specific survival (p = 0.001) compared to Stage I-II controls, however there was no difference in disease-free survival (p = 0.08). PDMs also demonstrated improved overall survival (p < 0.0001), melanoma-specific survival (p < 0.0001) and disease-free survival (p < 0.0001) compared to Stage IV M1a controls.

CONCLUSION

These findings demonstrate that PDMs have a more favorable prognosis compared to stage I-II cutaneous melanomas and suggest that these are in fact true primary lesions. This study thus provides evidence to justify a treatment approach, by way of a wide local excision and possibly sentinel lymph node biopsy, as for early stage primary cutaneous melanomas.

Melanoma of unknown primary

Formally described in the 1960s, melanoma of unknown primary (MUP) is characterized by the finding of metastatic melanoma within the lymph nodes, subcutaneous tissues, and other distant sites without an evident primary lesion. The most likely hypothesis of its etiology is an immune-mediated regression of the primary after metastasis has occurred. In addition, patients with MUP appear to have equivalent or better outcomes compared with patients with known primaries of a similar stage.

Unusual Clinical Presentations of Malignant Melanoma: A Review of Clinical and Histologic Features with Special Emphasis on Dermatoscopic Findings

This review presents the main challenges encountered when diagnosing unusual variants of malignant melanoma with the aim of raising awareness to allow application of the most appropriate treatment strategies. Although these melanomas are often rare, their misdiagnosis potentially jeopardizes patients' health and survival, and has medicolegal implications. The clinical and histologic presentations of melanoma vary greatly, and assessment of uncommon melanomas can be difficult for practitioners because of their scarcity and resemblance to other dermatologic entities. The most problematic melanoma types are desmoplastic melanoma, polypoid melanoma, primary dermal melanoma, verrucous malignant melanoma, pigmented epithelioid melanocytoma, mucosal melanoma, follicular melanoma and melanoma with non-melanocytic differentiation. The two most difficult-to-diagnose subtypes of melanoma are the nevoid and the amelanotic melanomas. Some specific attributes of these variants can be more easily recognized with digital dermatoscopy, facilitating early detection and possibly avoiding invasive procedures. Key cases with the most notable clinical, dermatoscopic, and histopathologic features are presented, highlighting the practical issues of making an accurate diagnosis and choosing the best therapy.

Clinical significance of tumor mitotic rate and lack of epidermal attachment in melanoma of the head and neck

BACKGROUND

The primary purpose of this study was to identify the prognostic role of primary dermal melanoma and tumor mitotic rate in melanomas of the head and neck.

METHODS

A retrospective review of the histopathologic, clinical, and demographic data of 256 patients was performed to investigate the impact of primary dermal melanoma and tumor mitotic rate on sentinel lymph node positivity, recurrence, and 5-year overall and disease-free survival.

RESULTS

Increased tumor mitotic rate, but not primary dermal melanoma, is a significant predictor of sentinel lymph node positivity and higher likelihood of recurrence. Survival analysis demonstrated that both increased tumor mitotic rate and primary dermal melanoma decreased the 5-year overall and disease-free survival rates of patients with head and neck melanoma lesions.

CONCLUSION

Tumor mitotic rate and primary dermal melanoma may have prognostic significance for both overall and disease-free survival in patients with head and neck melanoma. A larger prospective study is warranted to further elucidate prognostic factors for melanoma in the head and neck region.

Cutaneous Melanocytoma With CRTC1-TRIM11 Fusion: Report of 5 Cases Resembling Clear Cell Sarcoma

We report 5 cases of primary intradermal nodular unpigmented tumors with a melanocytic immunophenotype associated with a novel CRTC1-TRIM11 fusion. Clinically, the cutaneous nodules were slowly growing in 3 women and 2 men (25 to 82 y old, median, 28 y) with no specific topography. Lesion size ranged from 4 to 12 mm (median, 5 mm). The tumors were strictly located in the dermis with a nodular pattern. The cells were arranged in confluent nests and fascicules. Central fibronecrotic areas were present in 2 cases. Cells were medium to large, sometimes multinucleated, and presented a spindled and epithelioid cytology with prominent nucleoli. Cytonuclear atypia was constant, and mitotic activity in hotspot areas ranged from 1 to 5/mm². Immunohistochemistry found a constant positivity with S100, MiTF, and Sox10, and a heterogenous staining by MelanA or HMB45. NTRK1 was strongly positive in 3 cases. In all cases, RNA sequencing found an invariable CRTC1(e1)-TRIM11(e2) fusion, confirmed by fluorescent in situ hybridization techniques with a TRIM11 break-apart probe. In 4/4 cases, nuclear TRIM11 expression was positive by immunohistochemistry. Fluorescent in situ hybridization techniques showed no rearrangement of NTRK1 or EWSR1, and array-comparative genomic hybridization displayed no alteration (1 case) or only a whole chromosome 7 gain (2 cases) when performed. No relapse or metastatic event was observed during follow-up [3 to 72 months (median, 14 mo)]. Cutaneous clear cell sarcoma was the main differential diagnosis. Overlapping morphologic features previously described in primary dermal melanomas and paraganglioma-like melanocytic tumors were present. The CRTC1-TRIM11 fusion appears to be specific of an unpigmented nodular tumor combining a melanocytic phenotype and low-grade tumor behavior.

Dermal melanoma: A report on prognosis, outcomes, and the utility of sentinel lymph node biopsy

INTRODUCTION

Historically dermal melanoma (DM) has been labeled as either stage IIIB (in-transit) or stage IV (M1a) disease. We sought to investigate the natural history of DM and the utility and prognostic significance of sentinel lymph node biopsy (SLNB).

METHODS

Patients with DM undergoing SLNB at a single center from 1998 to 2009 were identified.

RESULTS

Eighty-three patients met criteria, 10 (12%) patients had a positive SLNB. Of those, 5 (50%) recurred (all with distant disease). Twenty-one (29%) of the 73 SLNB negative patients recurred and of those, 15 (71%) developed distant metastases, whereas 6 (29%) developed local or regional recurrence, including two false-negative regional nodal recurrences. No in-transit recurrences were recorded. Five-year recurrence-free and disease-specific survival was significantly better for patients with a negative SLNB versus positive SLNB (56.8% vs. 22.2% P = 0.02, 81.1% vs. 61.0%, P = 0.05, respectively).

CONCLUSION

SLNB has prognostic significance for RFS and DSS, and should be utilized in the management of DM based on a >10% yield and low false-negative rate. Our data demonstrate patients with DM do not recur in an in-transit fashion, which along with the survival outcomes suggest the behavior of DM is consistent with primary cutaneous melanoma of similar thickness rather than an isolated in-transit or distant dermal metastasis from a regressed cutaneous primary.

Primary dermal melanoma: a West Australian cohort

BACKGROUND

The objectives of this study were to identify a subgroup of patients with putative primary dermal melanoma after thorough multidisciplinary clinical and histological evaluation, and to describe the clinical, histological and selected molecular features of these lesions.

METHODS

The records of the Western Australian Melanoma Advisory Service were searched for potential cases of primary dermal melanoma. The clinical and histological features were reviewed, immunohistochemical assessment was performed and clinical outcomes recorded.

RESULTS

Eighteen cases of putative primary dermal melanoma with available clinical data were identified. Two of 12 cases in which further histological sections could be obtained were excluded because of the presence of findings suggesting an epidermal origin on these further sections. In one additional case, such origin could not be histologically excluded. Median follow-up period for the remaining cases was 68 months. Confirmed primary dermal melanoma accounts for 0.87% of cases of melanoma referred to a subspecialist melanoma advisory service. These cases show significant histological overlap with dermal/subcutaneous metastases of melanoma, but display a relatively good prognosis, with a 5-year survival of 87.5%.

CONCLUSION

Our results support the recognition of a distinct group of melanoma that mimics metastatic melanoma, but is associated with a relatively favourable outcome. The group of putative primary dermal melanoma is likely to be heterogenous, including cases of primary nodular melanoma in which epidermal connection has not been identified, metastatic melanoma with an occult primary lesion and true primary dermal melanoma.

Treatment of Regional Metastatic Melanoma of Unknown Primary Origin

(1) Background: The purpose of this retrospective study was to evaluate the recurrence and survival rates of metastatic melanoma of unknown primary origin (MUP), in order to further refine current recommendations for the surgical treatment; (2) Methods: Medical data of all MUP patients registered between 2000 and 2011, were analyzed. Seventy-eight patients were categorized in either lymph node (axilla, groin, head-and neck) or subcutaneous MUP. Axillary node MUPs were generally treated with dissections of levels I-III, inguinal node MUPs with combined superficial and deep groin dissections, and head-and-neck node MUPs with neck dissections to various extents, based on lymph drainage patterns. Subcutaneous lesions were excised with 1–2 cm margins. The primary outcome was treatment outcomes in terms of (loco)regional recurrence and survival rates; (3) Results: Lymph node MUP recurred regionally in 11% of patients, with an overall recurrence rate of 45%. In contrast, subcutaneous MUP recurred locally in 65% of patients with an overall recurrence rate of 78%. This latter group had a significantly shorter disease-free interval than patients with lymph node MUP (p = 0.000). In the entire study population, 5-year and 10-year overall survival rates were 56% and 47% respectively, with no differences observed between the various subgroups; (4) Conclusion: The relatively low regional recurrence rate after regional lymph node dissection (11%) supports its current status as standard surgical treatment for lymph node MUP. Subcutaneous MUP, on the contrary, appears to recur both locally (65%) and overall (78%) at a significantly higher rate, suggesting a different biological behavior. However, wide local excision remains the best available option for this specific group.

Utility of sentinel lymph node biopsy for solitary dermal melanomas

BACKGROUND AND OBJECTIVES

Solitary dermal melanoma (SDM) is melanoma confined to subcutaneous and/or dermal layers in the absence of a known primary cutaneous lesion. We hypothesized that sentinel node biopsy is an effective staging strategy for this rare disease.

METHODS

A Markov decision model was constructed to represent two management strategies for SDM: wide local excision followed by observation, and wide local excision followed by sentinel node biopsy. Utilities, likelihood of positive sentinel node biopsy, and cancer progression rates during a five year time horizon were assigned based on institutional data and a review of existing literature. Estimated costs were derived using Medicare reimbursements.

RESULTS

Excision followed by sentinel node biopsy provides greater utility, yielding 3.85 discounted quality-adjusted life years (dQALY) compared to 3.66 for excision alone. The incremental cost-effectiveness ratio for sentinel node biopsy is $19,102 per dQALY. Sensitivity analyzes demonstrated that observation is more cost-effective if greater than 23% of sentinel node biopsies are positive (16% reported), or if 5-year survival for observed patients is greater than 76% (69% reported).

CONCLUSIONS

Based on existing clinical evidence, sentinel node biopsy yields greater utility than excision alone and is cost-effective for patients presenting with solitary dermal melanoma.

Primary dermal melanoma: a unique subtype of melanoma to be distinguished from cutaneous metastatic melanoma: a clinical, histologic, and gene expression-profiling study

BACKGROUND

Primary dermal melanoma (PDM) is a subtype of melanoma confined to the dermis that may be morphologically impossible to distinguish from cutaneous metastatic melanoma (CMM).

OBJECTIVE

We sought to better characterize PDM by describing the clinical, histologic, and molecular features of 49 cases of PDM and determine whether a gene expression-profiling test could help distinguish PDM from CMM.

METHODS

We describe 49 cases of PDM and determined whether any clinical or histopathologic features had a statistically significant relationship with outcome. Secondly, we performed a melanoma gene expression-profiling test on a subset of the PDM and CMM cases.

RESULTS

Overall recurrence was infrequent and seen in 9 of 49 cases. Six patients had locoregional recurrences and 3 patients had distant metastasis. None of the clinical or histologic parameters showed a statistically significant relationship with recurrence. There was a statistically significant association of a class I signature by DecisionDx-Melanoma assay (Castle Biosciences Inc, Friendswood, TX) for PDM whereas CMM were more frequently class II (P value = .023).

LIMITATIONS

The mean follow-up time was 26 months.

CONCLUSIONS

Most conventional staging parameters used for prognosis in cutaneous melanoma have limited applicability to PDM. The melanoma prognostic assay may be a useful tool for distinguishing PDM from CMM.

Metastatic melanomas of unknown primary show better prognosis than those of known primary: a systematic review and meta-analysis of observational studies

BACKGROUND

Melanoma of unknown primary (MUP) is a condition of metastatic melanoma without a primary lesion.

OBJECTIVE

We sought to identify the prognosis of MUP compared with melanoma of known primary (MKP).

METHODS

We searched for observational studies containing at least 10 patients with MUP from MEDLINE and EMBASE from inception to December 22, 2012. The outcomes of interest were overall and disease-free survival; meta-analyses of hazard ratio stratified by stage using a random effects model were performed. In addition, second systematic review identified risk factors influencing the survival of patients with MUP.

RESULTS

Eighteen studies including 2084 patients with MUP and 5894 with MKP were included. MUP had a better overall survival compared with MKP in stage III (15 studies; hazard ratio 0.83, 95% confidence interval 0.73-0.96, P = .010) and stage IV (6 studies; hazard ratio 0.85, 95% confidence interval 0.75-0.96, P = .008). Secondly, 22 studies including 3312 patients with MUP were reviewed, and increased stage and old age were the risk factors in patients with MUP.

LIMITATIONS

Diverse observational studies were reviewed, and selection and reporting biases are possible.

CONCLUSIONS

The current meta-analyses suggest better survival outcomes in patients with MUP than those in patients with MKP with the same corresponding tumor stage.

Primary dermal melanoma in a patient with a history of multiple malignancies: a case report with molecular characterization

Introduction

Primary dermal melanoma (PDM) is a recently described clinical entity accounting for less than 1% of all melanomas. Histologically, it is located in the dermis or subcutaneous tissue, and it shows no connections with the overlying epidermis. The differential diagnosis is principally made along with that of metastatic cutaneous melanoma.

Case Report

A 72-year-old Caucasian woman with a history of multiple cancers (metachronous bilateral breast cancer, meningioma, clear cell renal cell carcinoma, uterine fibromatosis and intestinal adenomatous polyposis), came to our attention with a nodular lesion on her back. After removal of the lesion, the histology report indicated malignant PDM or metastatic malignant melanoma. The clinical and instrumental evaluation of the patient did not reveal any other primary tumour, suggesting the primitive nature of the lesion. The absence of an epithelial component argued for a histological diagnosis of PDM. Subsequently, the patient underwent a wide surgical excision with sentinel node biopsy, which was positive for metastatic melanoma. Finally, the mutational status was studied in the main genes that regulate proliferation, apoptosis and cellular senescence. No pathogenetic mutations in CDKN2A, BRAF, NRAS, KRAS, cKIT, TP53 and PTEN genes were observed. This suggests that alternative pathways and low-frequency alterations may be involved.

Conclusions

The differential diagnosis between PDM and isolated metastatic melanoma depends on the negativity of imaging studies and clinical findings for other primary lesions. This distinction is important because 5-year survival rates in such cases are higher than in metastatic cases (80–100 vs. 5–20%, respectively).

Primary dermal melanoma: a case report and a review of the literature

Patients with cutaneous metastatic melanoma of unknown primary origin (stage IV M1a disease according to the American Joint Committee on Cancer melanoma staging system) have an estimated 5-year survival rate of between 5% and 17.9% and a median survival of 6 months. However, certain patients with stage IV M1a disease have much higher survival rates. The existence of this subpopulation has given rise to the term primary dermal melanoma to describe such cases. We report a case of melanoma with characteristics consistent with primary dermal melanoma and review the relevant literature. A diagnosis of primary dermal melanoma requires careful clinical and pathologic correlation and should be considered in all patients with a solitary melanoma confined to the dermis and subcutaneous tissue when there is no evidence of a primary tumor or disease at other sites following appropriate staging studies. We believe that familiarity with this subtype of melanoma is essential in order to provide patients with optimal care and better prognostic information.

Paraganglioma-like dermal melanocytic tumor: a case report with particular features

Childhood dermal tumors with melanocytic features is an unusual tumor that can create diagnostic confusion. Among them, paraganglioma-like melanocytic tumors- previous included in melanocytic tumors of uncertain malignant potential- has some particular histopathologic and immunohistochemical features. We describe a case of 13 years old girl with a paraganglioma-like dermal melanocytic tumor of the left leg.