Desmoplastic melanoma

Desmoplastic Melanoma

Desmoplastic melanoma is a rare fibrosing variant of melanoma. It typically affects elderly patients but can occasionally affect young or middle-aged individuals. Desmoplastic melanoma is relevant as a diagnostic pitfall for pure tumor variants' distinct histopathologic and clinical features. The latter includes a lower regional lymph node involvement frequency and a more favorable prognosis among thick melanomas. Classic cases of desmoplastic melanoma tend to carry a high mutation burden. Patients with metastases from those tumors tend to respond favorably to novel immunotherapies.

The Role of Extracellular Matrix Remodeling in Skin Tumor Progression and Therapeutic Resistance

The extracellular matrix remodeling in the skin results from a delicate balance of synthesis and degradation of matrix components, ensuring tissue homeostasis. These processes are altered during tumor invasion and growth, generating a microenvironment that supports growth, invasion, and metastasis. Apart from the cellular component, the tumor microenvironment is rich in extracellular matrix components and bound factors that provide structure and signals to the tumor and stromal cells. The continuous remodeling in the tissue compartment sustains the developing tumor during the various phases providing matrices and proteolytic enzymes. These are produced by cancer cells and stromal fibroblasts. In addition to fostering tumor growth, the expression of specific extracellular matrix proteins and proteinases supports tumor invasion after the initial therapeutic response. Lately, the expression and structural modification of matrices were also associated with therapeutic resistance. This review will focus on the significant alterations in the extracellular matrix components and the function of metalloproteinases that influence skin cancer progression and support the acquisition of therapeutic resistance.

Fibroblast MMP14-Dependent Collagen Processing Is Necessary for Melanoma Growth

Simple Summary

Matrix metalloproteinases (MMPs) were considered as targets for the treatment of various cancers. However, initial trials using broad inhibitors to MMPs have failed, partly attributed to the contrasting functions of these proteases acting as tumor promoters and suppressors, among other reasons. Our data now suggest that specific inhibition of MMP14 might represent a more specific approach, as loss of this protease in fibroblasts resulted in reduced growth of grafted melanomas. Here, we found that deletion of MMP14 in fibroblasts generates a matrix-rich environment that reduces tumor vascularization and melanoma cell proliferation. In in vitro and ex vivo assays, we showed that the latter is mediated by stiffening of the tissue due to collagen accumulation. Additionally, in vivo, we show that independently of MMP14 deletion, a collagen-rich stiff matrix inhibits the growth of melanomas.

Abstract

Skin homeostasis results from balanced synthesis and degradation of the extracellular matrix in the dermis. Deletion of the proteolytic enzyme MMP14 in dermal fibroblasts (MMP14^Sf−/−) leads to a fibrotic skin phenotype with the accumulation of collagen type I, resulting from impaired proteolysis. Here, we show that melanoma growth in these mouse fibrotic dermal samples was decreased, paralleled by reduced tumor cell proliferation and vessel density. Using atomic force microscopy, we found increased peritumoral matrix stiffness of early but not late melanomas in the absence of fibroblast-derived MMP14. However, total collagen levels were increased at late melanoma stages in MMP14^Sf−/− mice compared to controls. In ex vivo invasion assays, melanoma cells formed smaller tumor islands in MMP14^Sf−/− skin, indicating that MMP14-dependent matrix accumulation regulates tumor growth. In line with these data, in vitro melanoma cell growth was inhibited in high collagen 3D spheroids or stiff substrates. Most importantly, in vivo induction of fibrosis using bleomycin reduced melanoma tumor growth. In summary, we show that MMP14 expression in stromal fibroblasts regulates melanoma tumor progression by modifying the peritumoral matrix and point to collagen accumulation as a negative regulator of melanoma.

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.

New observations in tumor cell plasticity: mutational profiling in a case of metastatic melanoma with biphasic sarcomatoid transdifferentiation

We describe a highly unusual case of metastatic melanoma in a 61-year-old female that manifested as a single groin lymph node metastasis accompanied by two distinct, subcutaneous sarcomatoid tumors on the same leg, without evidence of a primary tumor. Characterization encompassed extensive immunohistochemical staining as well as next-generation sequencing (NGS). The lymph node metastasis showed obvious features of melanoma. The two subcutaneous lesions, however, were morphologically and immunohistochemically consistent with high-grade myxofibrosarcoma and soft tissue mixed tumor, respectively. All three lesions were BRAF wild-type and found to harbor an identical NRAS p.Q61R mutation. Metachronic intestinal metastases, showing intermingled conventional and sarcomatoid morphology, as well as an identical genetic phenotype, corroborated these findings. The concordant genetic profile provided evidence of biphasic sarcomatoid transdifferentiation of melanoma. Interestingly, the lack of genetic heterogeneity between the three morphologically distinct tumors suggests factors other than genetic mutations to be involved in melanoma transdifferentiation.

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.

Melanoma Extirpation with Immediate Reconstruction: The Oncologic Safety and Cost Savings of Single-Stage Treatment

BACKGROUND

The timing of reconstruction following melanoma extirpation remains controversial, with some advocating definitive reconstruction only when the results of permanent pathologic evaluation are available. The authors evaluated oncologic safety and cost benefit of single-stage neoplasm extirpation with immediate reconstruction.

METHODS

The authors reviewed all patients treated with biopsy-proven melanoma followed by immediate reconstruction during a 3-year period (January of 2011 to December of 2013). Patient demographic data, preoperative biopsies, operative details, and postoperative pathology reports were evaluated. Cost analysis was performed using hospital charges for single-stage surgery versus theoretical two-stage surgery.

RESULTS

During the study period, 534 consecutive patients were treated with wide excision and immediate reconstruction, including primary closure in 285 patients (55 percent), local tissue rearrangement in 155 patients (30 percent), and skin grafting in 78 patients (15 percent). The mean patient age was 67 years (range, 19 to 98 years), and the median follow-up time was 1.2 years. Shave biopsy was the most common diagnostic modality, resulting in tumor depth underestimation in 30 patients (6.0 percent). Nine patients (2.7 percent) had positive margins on permanent pathologic evaluation. The only variables associated with positive margins were desmoplastic melanoma (p = 0.004) and tumor location on the cheek (p = 0.0001). The mean hospital charge for immediate reconstruction was $22,528 compared with the theoretical mean charge of $35,641 for delayed reconstruction, leading to mean savings of 38.5 percent (SD, 7.9 percent).

CONCLUSION

This large series demonstrates that immediate reconstruction can be safely performed in melanoma patients with an acceptable rate of residual tumor requiring reoperation and significant health care cost savings.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

A case of recurrent desmoplastic malignant melanoma presenting as empyema with underlying lung mass

Desmoplastic malignant melanoma (DMM) is an extremely rare subtype of cutaneous melanoma that has diverse clinical presentations. We describe the unique case of a 57-year-old man presenting with empyema secondary to vascular occlusion from metastatic DMM. Only two other cases of DMM presenting as a lung mass have been previously reported in the literature. This report highlights potential insidious pathology of DMM, which requires a high clinical suspicion to properly diagnose and manage.

Surgical Management of Melanoma

The surgical management of melanoma has undergone considerable changes over the past several decades, as new strategies and treatments have become available. Surgeons play a pivotal role in all aspects of melanoma care: diagnostic, curative, and palliative. There is a high potential for cure in patients with early-stage melanoma and the selection of an appropriate operation is very important for this reason. Staging the nodal basin has become widespread since the adoption of sentinel lymph node biopsy (SLNB) for the management of melanoma. This operation provides the best prognostic information that is currently available for patients with melanoma. The surgeon plays a central role in the palliation of symptoms resulting from nodal disease and metastases, as melanoma has a propensity to spread to almost any site in the body.

A Newly Developed Mouse Monoclonal SOX10 Antibody Is a Highly Sensitive and Specific Marker for Malignant Melanoma, Including Spindle Cell and Desmoplastic Melanomas

Context

Recent immunohistochemical studies have demonstrated Sry-related HMG-Box gene 10 (SOX10) expression in malignant melanomas, malignant peripheral nerve sheath tumors, a subset of breast carcinomas, and gliomas. SOX10 has shown important clinical utility in its ability to detect desmoplastic and spindle cell melanomas. To date, most publications have employed a research use–only goat polyclonal SOX10 antibody for immunohistochemical staining.

Objective

To describe the development of a new mouse monoclonal SOX10 antibody (BC34) and evaluate its immunohistochemical staining profile in a wide range of normal and neoplastic tissues, with an emphasis on melanoma.

Design

SOX10 antibody was optimized for staining using a polymer detection system and visualization with diaminobenzidine.

Results

In normal tissues, SOX10 was expressed in skin melanocytes and eccrine cells, breast myoepithelial and lobular epithelial cells, salivary gland myoepithelial cells, peripheral nerve Schwann cells, and central nervous system glial cells. SOX10 was expressed in 238 of 257 melanomas (92.6%), including 50 of 51 of both spindle cell and desmoplastic melanomas (98%). SOX10 was expressed in 100% of nevi (20 of 20) and schwannomas (28 of 28). In other neoplasms, SOX10 was expressed in 18 of 109 invasive ductal breast carcinomas (16.5%). All other carcinomas were negative for SOX10. SOX10 was identified in 25 of 52 central nervous system neoplasms, primarily in astrocytomas (22 of 41; 53.7%), and in 4 of 99 various sarcomas examined (4.0%).

Conclusions

The newly developed mouse monoclonal SOX10 antibody BC34 is highly sensitive and specific for malignant melanoma, including desmoplastic and spindle cell variants, and appears highly suitable for clinical use.

Immunoexpression of S100A4 in canine skin melanomas and correlation with histopathological parameters

BACKGROUND

Melanoma is one of the most common skin neoplasms in humans and dogs. The tumor microenvironment in melanoma comprises cancer cells and stromal cells that interact to accelerate tumor progression. Several prognostic markers for melanomas have been studied in many human tumors, including fibroblast-specific protein 1 (S100A4). S100A4 is a member of the S100 family of calcium-binding proteins in stromal cells.

HYPOTHESIS/OBJECTIVES

The objective of this study was to describe the immunohistochemical patterns of S100A4 in stroma and neoplastic cells of canine skin melanomas and correlate them with some histological parameters.

ANIMALS AND METHODS

Forty-eight samples (38 pigmented and 10 non-pigmented melanomas) were first selected and their nature confirmed using S100, Melan A and vimentin. All cases were examined by immunohistochemistry using S100A4 to correlate expression, histotype, and level of invasion.

RESULTS

All the tumors, including 10 non-pigmented, were positive for S100, Melan A, vimentin and negative for cytokeratin AE1/AE3 (consistent with melanomas). The 48 melanomas were classified as epithelioid (n = 21), spindle (n = 14), and mixed (n = 13). S100A4 was preferentially expressed in epithelioid and spindle cell types compared with mixed melanomas and S100A4 expression was not associated with level of invasion (Clark's levels IV to V).

CONCLUSION

S100A4 expression in melanoma samples varied among histotypes but not between levels of invasion.

Desmoplastic melanoma with sarcomatoid dedifferentiation

Desmoplastic melanoma (DM) is a variant of melanoma, which typically affects chronically sun-damaged skin of elderly patients. Pure DM displays a low density of fusiform melanocytes in a collagen-rich matrix. In mixed DM, tumor cell density is higher, and parts of the tumor lack abundant stromal fibrosis. Both pure and mixed DMs usually express S100 protein homogenously. We report herein an unusual biphenotypic tumor characterized by the association of a pure DM with an undifferentiated solid spindle cell nodule. It occurred on the scalp of a 66-year-old man. A biopsy of the undifferentiated spindle cell nodule was initially interpreted at a commercial laboratory as atypical fibroxanthoma. The pure DM was seen only in the excisional specimen. All cells of the pure DM stained for S100 protein and SOX10. The adjacent solid sarcomatoid spindle cell nodule lacked expression of S100 protein, SOX10, as well as melan-A, gp100, and microphthalmia-associated transcription factor in >95% of its tumor cells. Although focal expression of melanocyte differentiation antigens in the solid tumor component made us favor a combined DM with sarcomatoid dedifferentiation, we also considered the possibility of a collision scenario, that is, a pleomorphic dermal sarcoma incidentally colliding with a DM. To further assess a possible relationship of the sarcomatoid nodule with the DM, we performed next-generation sequencing analysis on each component separately. The analysis revealed shared chromosomal copy number changes and a high number of common mutations, thereby supporting the concept of a DM with a dedifferentiated sarcomatoid component. An interesting finding is the presence of mutations of the neurofibromin 1 (NF1) gene in both tumor components.

Priming cancer cells for drug resistance: role of the fibroblast niche

Conventional and targeted chemotherapies remain integral strategies to treat solid tumors. Despite the large number of anti-cancer drugs available, chemotherapy does not completely eradicate disease. Disease recurrence and the growth of drug resistant tumors remain significant problems in anti-cancer treatment. To develop more effective treatment strategies, it is important to understand the underlying cellular and molecular mechanisms of drug resistance. It is generally accepted that cancer cells do not function alone, but evolve through interactions with the surrounding tumor microenvironment. As key cellular components of the tumor microenvironment, fibroblasts regulate the growth and progression of many solid tumors. Emerging studies demonstrate that fibroblasts secrete a multitude of factors that enable cancer cells to become drug resistant. This review will explore how fibroblast secretion of soluble factors act on cancer cells to enhance cancer cell survival and cancer stem cell renewal, contributing to the development of drug resistant cancer.

Postradiation cutaneous pleomorphic rhabdomyosarcoma with extracellular collagen deposits reminiscent of so-called amianthoid fibers

Rhabdomyosarcoma is a malignant mesenchymal neoplasm that rarely presents as primary skin tumor. So-called amianthoid fibers are hyalinized collagen mats that have been described in myofibroblastic tumors but not in rhabdomyosarcoma. A 65-year-old male developed a submandibular nodule 9 years after an oral squamous cell carcinoma, which had been treated with chemotherapy and radiotherapy. Histological examination of the nodule revealed a pleomorphic rhabdomyosarcoma with extracellular collagen deposits reminiscent of so-called amianthoid fibers. By immunohistochemistry, the tumor cells were positive for vimentin, desmin, smooth muscle actin (SMA), muscle-specific actin (MSA), CD10, CD56, CD99, β-catenin and D2-40. However, only 15-20% of the tumor cells were positive for myoglobin, MyoD1 and myf-4/myogenin. We describe first so-called amianthoid fibers harboring blood capillaries in a rhabdomyosarcoma, suggesting that they are rigid collagen structures that lead to tumor vascularization. The low expression for myogenic regulatory proteins and strong expression for other markers may be misleading and do not contribute to the diagnosis of rhabdomyosarcoma.

The molecular pathology of melanoma: an integrated taxonomy of melanocytic neoplasia

Melanomas comprise multiple biologically distinct categories, which differ in cell of origin, age of onset, clinical and histologic presentation, pattern of metastasis, ethnic distribution, causative role of UV radiation, predisposing germ-line alterations, mutational processes, and patterns of somatic mutations. Neoplasms are initiated by gain-of-function mutations in one of several primary oncogenes, which typically lead to benign melanocytic nevi with characteristic histologic features. The progression of nevi is restrained by multiple tumor-suppressive mechanisms. Secondary genetic alterations override these barriers and promote intermediate or overtly malignant tumors along distinct progression trajectories. The current knowledge about the pathogenesis and clinical, histologic, and genetic features of primary melanocytic neoplasms is reviewed and integrated into a taxonomic framework.

Ras, Raf, and MAP kinase in melanoma

A growing understanding of the biology and molecular mechanisms of melanoma has led to the identification of a number of driver mutations for this aggressive tumor. The most common mutations affect signaling of the Ras/Raf/MAPK (mitogen-activated protein kinase) pathway. This review will focus on mutations in genes encoding proteins that play a role in the MAPK pathway and that have been implicated in melanoma biology, such as BRAF, NRAS, and MEK (MAPK kinase), and detail the current understanding of their role in melanoma progression from a molecular biology perspective. Furthermore, this review will also consider some additional mutations in genes such as KIT, GNAQ, and GNA11, which can be seen in certain subtypes of melanoma and whose gene products interact with the MAPK pathway. In addition, the association of these molecular changes with clinical and classical histopathologic characteristics of melanoma will be outlined and their role in diagnosis of melanocytic lesions discussed. Finally, a basic overview of the current targeted therapy landscape, as far as relevant to the pathologist, will be provided.

Immunohistochemical expression of p16 in desmoplastic melanoma

Desmoplastic melanoma can be difficult to distinguish from desmoplastic melanocytic nevi both clinically and histopathologically. Several attempts have been made to explore the use of ancillary studies to facilitate this distinction. Prior work has suggested that immunohistochemical expression of p16 could help distinguish sclerosing Spitz nevi from desmoplastic melanomas. We re-evaluated the expression of p16 in 22 desmoplastic melanomas (13 mixed and 9 pure desmoplastic tumors) and five desmoplastic melanocytic nevi (three desmoplastic Spitz nevi and two congenital melanocytic nevi with prominent dermal sclerosis). All desmoplastic melanocytic nevi were strongly immunoreactive for p16. Of the 22 desmoplastic melanomas, 6 tumors failed to label for p16, 10 were focally positive, but 6 tumors were diffusely immunoreactive. The latter finding is relevant, as it points to limitations in the diagnostic value of immunohistochemical staining for p16 for the diagnosis of desmoplastic melanocytic proliferations. Diffuse staining for p16 is not restricted to desmoplastic Spitz nevi but can also occur in a subset of desmoplastic melanomas, and this warrants caution in the use of this marker for diagnostic purposes.

Desmoplastic melanoma: a diagnostic dilemma

Desmoplastic melanoma (DM) is an uncommonly encountered type of melanoma. A pigmentation is frequently absent, although a lentigo or lentigomaligna-like discolouration, adjacent to the nodule, is not uncommon. Hence, the clinical impression at presentation may vary from those of basal cell or squamous cell carcinomas, dermatofibromas or sarcomas to cysts and indurated plaque-like lesions which resemble scars. Making a cinical diagnosis of this tumour is difficult and it may very often mislead the physician. The clinical appearance of DM may be highly variable and the diagnosis of the tumour is difficult. We are reporting a case of DM which was diagnosed histopathologically and confirmed by immunohistochemistry (IHC), for its rarity and unique presentation.

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 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.

Soft Tissue Pseudosarcomas

Soft tissue pathology is one of the most challenging areas of diagnostic pathology, not only because of the morphologic diversity of such lesions, but also because of their rarity and pathologists' subsequent lack of exposure to these tumors. Many lesions mimic malignant mesenchymal neoplasms, collectively referred to as "pseudosarcomas." The list of proliferations that can simulate a sarcoma is extensive and heterogeneous. This review addresses malignant, nonmesenchymal neoplasms; mesenchymal neoplasms that histologically mimic sarcomas but are benign; and benign reactive soft tissue lesions that are neither neoplastic nor malignant, but have worrisome clinical and/or morphologic features.