Variants of melanoma

Advancements in nanoparticle-based treatment approaches for skin cancer therapy

Skin cancer has emerged as the fifth most commonly reported cancer in the world, causing a burden on global health and the economy. The enormously rising environmental changes, industrialization, and genetic modification have further exacerbated skin cancer statistics. Current treatment modalities such as surgery, radiotherapy, conventional chemotherapy, targeted therapy, and immunotherapy are facing several issues related to cost, toxicity, and bioavailability thereby leading to declined anti-skin cancer therapeutic efficacy and poor patient compliance. In the context of overcoming this limitation, several nanotechnological advancements have been witnessed so far. Among various nanomaterials, nanoparticles have endowed exorbitant advantages by acting as both therapeutic agents and drug carriers for the remarkable treatment of skin cancer. The small size and large surface area to volume ratio of nanoparticles escalate the skin tumor uptake through their leaky vasculature resulting in enhanced therapeutic efficacy. In this context, the present review provides up to date information about different types and pathology of skin cancer, followed by their current treatment modalities and associated drawbacks. Furthermore, it meticulously discusses the role of numerous inorganic, polymer, and lipid-based nanoparticles in skin cancer therapy with subsequent descriptions of their patents and clinical trials.

Actualities in the Morphology and Immunohistochemistry of Cutaneous and Ocular Melanoma: What Lies Ahead? A Single-Centre Study

Melanoma is the most aggressive melanocytic tumor whose incidence is continuously increasing worldwide.

METHODS

We highlight the morphological, immunohistochemistry, and particularities of various melanoma types based on the cases diagnosed in our department from 2017 to 2021.

RESULTS

We present 100 melanoma cases and one capsular nevus case. The most common type was nodular melanoma. The immunohistochemistry markers used were SRY-box transcription factor 10 (SOX10), S100 protein, human melanoma black 45 (HMB45), and melanoma antigen recognized by T cells 1 (Melan-A). Uveal melanoma and conjunctival melanoma represent particular tumors with independent prognostic factors. Uveal melanoma requires assessment of macrophages, microvascularisation, and mitoses. Sentinel lymph node metastases are essential targets that provide staging tools. Conjunctival melanoma and capsular nevi are diagnostic pitfalls.

CONCLUSION

Melanoma can appear in various forms, and sometimes the diagnosis might be unclear. Today, immunohistochemistry remains the most important tool in confirming the diagnosis and prognosis for this type of neoplasia.

Retrospective Cohort: Genomic Differences Between Pigmented Spindle Cell Nevi of Reed and Reed-Like Melanomas

BACKGROUND

Some melanomas closely resemble pigmented spindle cell nevi (PSCN) of Reed histologically. The distinction of these entities is important for clinical management. A recent study showed most PSCN (78%) are fusion-driven, commonly involving NTRK3 (57%). Conversely, BRAF V600E mutations are not characteristic of PSCN but are frequent in melanoma.

OBJECTIVE

In this study, we assessed clinical, histologic and genomic differences between PSCN of Reed and Reed-like melanomas (RLMs).

METHODS

We performed BRAF V600E immunohistochemistry (IHC) for 18 PSCN and 20 RLM cases. All 23 benign PSCN cases previously underwent whole transcriptome and targeted DNA sequencing with a 1711 gene panel.

RESULTS

We previously demonstrated the majority of PSCN (18 of 23) has chimeric fusions. Among PSCN without a chimeric fusion, BRAF mutations were common. Noncanonical BRAF mutations were identified in 2 of 5 nonfusion cases, and 1 case had a canonical BRAF mutation. Alternatively, 70% of RLM demonstrated a BRAF V600E mutation. RLM also occurred more frequently in older patients.

LIMITATIONS

The overall sample size was small.

CONCLUSIONS

In diagnostically challenging cases, ancillary IHC studies can assist in distinguishing PSCN from RLM. Our study suggests positive staining by IHC for BRAF V600E and older age strongly favors a diagnosis of RLM.

Spitz nevus and Reed nevus

Spitz and Reed nevi, also called spindle and/or epithelioid cell nevi, are a special group of melanocytic lesions due to their peculiar clinical, dermoscopic and histopathological features. The study of these nevi is of great interest because both their nomenclature and classification are still a matter of discussion. Most importantly, the difficulty to differentiate them from melanoma can lead to inadequate therapies. In this context, dermoscopy, a link between clinical and anatomopathological examinations, appears as a helpful diagnostic tool whose accuracy can reach 93%. "Borderline" lesions are still a great challenge and object of research, including molecular studies. The present study explores the relevant characteristics of these nevi, with emphasis on dermoscopic findings, aiming at understanding their natural history, as well as discussing treatment and patient follow-up.

Unusual histologic and clinical variants of melanoma: Implications for therapy

Unusual histologic variants of melanoma may be problematic to the histopathologist. Several of these variants are sufficiently rare that their biologic behavior remains obscure. As identification of some of these melanoma subtypes has specific implications for the therapeutic approach, and as some may mimic other forms of epithelial or mesenchymal neoplasia, their recognition is key to patient management.

Melanocytic nevi simulant of melanoma with medicolegal relevance

A group of melanocytic benign nevi are prone to be misdiagnosed as nodular or superficial spreading melanoma. This review illustrates the most frequent forms of these nevi in direct comparison with their malignant morphologic counterparts. The nevi are: hyper-cellular form of common nevus to be distinguished from nevoid melanoma, Spitz nevus (vs spitzoid melanoma), Reed nevus (vs melanoma with features of Reed nevus), cellular atypical blue nevus (vs melanoma on blue nevus), acral nevus (vs acral melanoma), Clark dysplastic nevus (vs superficial spreading melanoma), desmoplastic nevi (vs desmoplastic melanoma), benign proliferative nodules in congenital nevi (vs melanoma on congenital nevi), epithelioid blue nevus (vs animal type melanoma) and regressed nevus (vs regressed melanoma). For each single 'pair' of morphological look-alikes, a specific set of morphological, immunohistochemical and genetic criteria is provided.

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.

Diagnosis and treatment of malignant melanoma of the foot

BACKGROUND

Patients diagnosed with melanoma of the foot have been reported to have a poor prognosis. We reviewed our experience at a tertiary-care medical clinic to determine the disease course in patients diagnosed with melanoma of the foot.

METHODS

A retrospective review was performed of 38 patients with a diagnosis of primary or locally recurrent melanoma of the foot treated between January, 1988, and July, 2004. The main outcome measures included methods of diagnosis, clinical and histopathologic features, and patterns of recurrence.

RESULTS

The mean age at diagnosis was 61 years; most were women (58%) and Caucasian (95%). The average time to diagnosis was 17 months. Initial clinical diagnosis had been considered benign in 12 (32%). The median Breslow thickness was 1.75 mm, T1 lesions were the most common, and acral lentiginous melanoma accounted for 42%. Thirteen patients (34%) had ulcerated lesions. Sentinel lymph node biopsy specimens of 25 patients identified four (16%) with metastatic disease. Surgical complications occurred in 12 patients, usually after skin graft or soft-tissue flap reconstruction. Systemic recurrence developed in six patients, four of whom also had regional recurrence.

CONCLUSIONS

Most patients were elderly Caucasian women and most presented with early-stage disease, but diagnosis can be difficult and a subgroup presented with thick melanomas. Reconstructive surgical procedures had a high rate of complications; however, overall functional outcomes were good. Stage of cancer at diagnosis was associated with systemic metastases.

Unusual histologic and clinical variants of melanoma: Implications for therapy

Unusual histologic variants of melanoma may prove problematic to the histopathologist. Several of these variants are sufficiently rare that their biological behavior remains obscure. Because identification of some of these melanoma subtypes has specific implications for the therapeutic approach and some may mimic other forms of epithelial or mesenchymal neoplasia, their recognition is key to patient management.

Medicolegal aspects of neoplastic dermatology

Medical malpractice litigation is rising at an explosive rate in the US and, to a lesser extent, in Canada. The impact of medical malpractice litigation on health care costs and the cost of insurance is dramatic. Certain specialist categories are becoming uninsurable in some parts of the US, while in others, clinicians are retiring early, restricting or changing practice or changing states of residence in consequence of medical malpractice claims and of the cost and availability of insurance. This, in turn, has had the real effect of denying care to patients in some communities in the US. Some 13% of all medical malpractice claims relate to one area of neoplastic dermatopathology, specifically, melanocytic neoplasia. Certain steps can be taken by pathology laboratories to reduce, but never completely eliminate, the risk of medical malpractice claims. In this review, attention is paid to the source of medical malpractice claims and an abbreviated approach to specific strategies for risk management is presented.

Unusual variants of malignant melanoma

A potential diagnostic pitfall in the histologic assessment of melanoma is the inability to recognize unusual melanoma variants. Of these, the more treacherous examples include the desmoplastic melanoma, the nevoid melanoma, the so-called 'minimal-deviation melanoma,' melanoma with prominent pigment synthesis or 'animal-type melanoma,' and the malignant blue nevus. Also problematic are the unusual phenotypic profiles seen in vertical growth phase melanomas; these include those tumors whose morphological peculiarities mimic cancers of nonmelanocytic lineage and those melanomas that express aberrant antigenic profiles not commonly associated with a melanocytic histogenesis. Metaplastic change in melanoma, balloon cell melanoma, signet-ring cell melanoma, myxoid melanoma, small cell melanoma and rhabdoid melanoma all have the potential to mimic metastatic and primary neoplasms of different lineage derivations. Abnormal immunohistochemical expression of CD 34, cytokeratins, epithelial membrane antigen, and smooth muscle markers as well as the deficient expression of S100 protein and melanocyte lineage-specific markers such as GP100 protein (ie HMB-45 antibody) and A103 (ie Melan-A) also present confusing diagnostic challenges. In this review, we will discuss in some detail certain of these novel clinicopathologic types of melanoma, as well as the abnormal phenotypic expressions seen in vertical growth phase melanoma.

Identification of histological features associated with metastatic potential in thin (<1.0 mm) cutaneous melanoma with metastases. A study on behalf of the EORTC Melanoma Group

Contrary to expectations, a small number of thin (<1 mm) melanomas do metastasize. This collaborative study was performed in an attempt to identify the morphological basis of such aggressive behaviour. Regression was expected to be the explanation for the lack of thickness in some cases. Whether a vertical growth phase (VGP) was present in the remainder was carefully assessed. A pilot study had identified two other patterns associated with metastasis in thin melanomas. These were termed 'junctional expansion nodules' and 'melanomatous follicular invasion'. Both were seen in the absence of other dermal invasion. These two patterns were included in the study, which comprised 54 cases and 56 controls, which were thin melanomas which had not metastasized 5 years after excision. Regression was present in 50% of test cases (30.4% in controls, p=0.036) and VGP was present in 59.3% of cases and 48.2% of controls. The thinnest metastasizing melanoma without regression was 0.27 mm. Eight (14.8%) cases, however, had metastasized but showed neither regression nor VGP; seven of these showed a junctional expansion nodule, present in only three controls (p=0.016). Five of these seven also showed melanomatous follicular invasion. One of these five showed this follicular involvement without a junctional nodule. Melanomatous follicular invasion was not seen in the control cases (p=0.012). Mitoses were seen in the VGP of both test and control cases, but high counts (>3 per mm(2)) were much more common in the metastasizing lesions (p=0.007). These findings support the idea that in most cases, regression and/or a VGP are required for metastasis to occur. However, a small number of thin melanomas without these features, as conventionally described, still metastasize. This implies that VGP may require redefinition and that junctional expansion nodules and melanomatous follicular invasion may be variants of VGP.

Morphological analysis of nevoid melanoma: a study of 20 cases with a review of the literature

Nevoid melanoma is a rare variant of melanoma characterized by deceptive morphologic features reminiscent of a benign melanocytic nevus. Twenty (13 nodular, 7 verrucous) nevoid melanomas were reviewed with the goal of identifying the predominant architectural patterns, cytologic features, and prognostic indicators. Although at scanning magnification, many lesions showed a strong resemblance to banal compound or dermal nevi, careful inspection in all cases demonstrated subtle pleomorphism and impaired maturation with depth, invariably accompanied by multiple dermal mitoses. Four tumors recurred and three metastasized, with subsequent death of the patients. Follow-up information for a period of at least 3 years was available in eight cases. In this group, mortality was 37.5%, the metastasis rate was 37.5%, and the local recurrence rate was 75%, with an average tumor thickness of 2.5 mm. We conclude that nevoid melanoma may be distinguished from a benign melanocytic nevus by a high index of suspicion, a careful analysis of architecture, and attention to cytologic features. Our data and a review of the literature do not support the notion that nevoid melanoma has a better prognosis than ordinary melanoma.

Dermabrasion of large congenital melanocytic naevi in neonates

We describe our findings in a series of 12 patients with large congenital melanocytic naevi treated with dermabrasion between the first and fourteenth week of life. Postoperative follow-up ranged from 1-16 years. In all but two cases dermabrasion resulted in an appreciable and stable reduction of the hyperpigmentation, possibly by reducing the number of pigmented cells in the epidermis. In six of our 12 patients, reconstruction using grafts and flaps was done to improve the aesthetic result. Seven years after dermabrasion, one patient developed a minimal deviation melanoma in the treated area, but his subsequent clinical course has been uneventful.

Minimal deviation and/or naevoid melanoma: is recognition worthwhile? A clinicopathological study of nine cases

One to two per cent of primary cutaneous melanomas share clinical features with benign melanocytic and non-melanocytic skin lesions, and even at histology recognition of their malignant nature is problematic, mainly due to the lack of an intraepithelial component, their nodular aspect and the monotonous cell population throughout the lesion. These tumours were termed minimal deviation melanomas (MDMs) by Reed et al. and later naevoid melanomas by Schmoeckel et al. The name MDM suggests the concept of a more favourable outcome for these melanomas that do not (yet) show the typical features of fully evolved lesions able to metastasize, although naevoid melanomas seem to behave like 'common' melanomas. In a retrospective analysis of nine cases of MDM collected from our database and followed for a median duration of 112 months, we faced similar clinical and histological pitfalls and observed local recurrence following marginal resection. Wide excision, even of local recurrence, and therapeutic node dissection could nevertheless provide survival comparable at least to that predicted by mathematical models for patients who initially had optimal treatment.

Small cell malignant melanoma: a variant of naevoid melanoma. Clinicopathological features and histological differential diagnosis

AIMS

To describe the clinical and histopathological features of a rare variant of naevoid melanoma, small cell melanoma, and discuss the histological differential diagnoses.

METHODS

The clinical and histological features of cases of malignant melanoma with the histological features of small (non-Merkel like) melanoma were reviewed and documented. In addition, five cases had available material for immunohistochemistry and this was performed using antibodies to the S100 protein and melan-A, and the HMB-45 antibody.

RESULTS

There were 15 cases of small cell melanoma from 14 (10 female, four male) patients, aged between 30 and 77 (mean, 48.6) years. The trunk was the most common location. In more than half the cases, the provisional diagnosis was melanoma/borderline lesion. All shared similar histological appearances of an intraepidermal component of in situ melanoma and a dermal component of nests of cells with hyperchromatic nuclei and scanty cytoplasm, usually in tightly packed nests. All components (junctional and intradermal) of the lesions investigated by immunohistochemistry were positive both for S100 protein and melan-A. All junctional components were positive with HMB-45, but with variable staining of the dermal components with this antibody.

CONCLUSIONS

Small cell malignant melanoma is postulated to be a distinct histopathological entity and a rare variant of naevoid melanoma. Such lesions can be difficult to interpret and easily missed at scanning magnification because the cells of the dermal component mimic benign naevus cells.

Problematic pigmented lesions: approach to diagnosis

A number of pigmented lesions are difficult to classify and raise the possibility of a melanoma diagnosis. Care should be exercised to exclude non-melanocytic lesions, and benign melanocytic entities, both of which can mimic melanoma histologically. In addition, the possibility of the lesion being a melanoma variant or epidermotropic metastasis should be considered. There will still be some cases that are difficult to resolve. These usually fall into one of three categories: atypical junctional melanocytic lesion versus early melanoma; naevus versus naevoid melanoma; and atypical Spitz, cellular blue, and deep penetrating naevi versus thick melanoma. These will pose problems even for experts. The atypical Spitz lesions are perhaps the most important category because they tend to be from younger individuals, the differential diagnosis is thick melanoma, and there is no single discriminating histological feature.

Dimensionalities: borderline and intermediate melanocytic neoplasia

The concept of minimal deviation melanoma is presented in diagrammatic form. In this approach, the precursors of melanoma are presented as having two dimensions and melanomas as having three dimensions. In turn, the relativity between dimensionalities and recommendations for treatment (as indirect correlates of prognostications) provides guidelines for the structuring of two major boundaries along the axis of the diagram. Finally, the domains defined by the two boundaries include borderline lesions, intermediate lesions, and "real melanomas." The lesions in the borderline and intermediate categories qualify as melanocytic neoplasias of indeterminant malignant potential; in these two categories, the predictability of metastases hardly justifies the use of the designation, malignant melanoma.

The melanocyte differentiation pathway in spitz nevi

The nature of Spitz nevi is poorly understood, and their distinction from malignant melanoma can be difficult. Although there is general agreement on the diagnostic criteria, experts continue to have some differences, and controversial cases are not rare. A major obstacle to progress in this area is the lack of basic knowledge about melanocyte differentiation in Spitz nevi, as compared with ordinary nevi and malignant melanomas. Based on the hypothesis that normal melanocytes may have a differentiation pathway with discrete stages, it is suggested that the features of Spitz nevi may reflect homeostatic mechanisms governing maturation in the melanocyte differentiation pathway, whereas those of malignant melanomas may reflect carcinogen-induced aberrations. This perspective may be helpful in the continuing effort to develop optimal criteria for the differential diagnosis of Spitz nevi from malignant melanomas.