Melanoma arising in a large plaque-type blue nevus with subcutaneous cellular nodules

The clinico-pathological spectrum of plaque-type blue naevi and their potential for malignant transformation

AIMS

Plaque-type blue naevi are rare melanocytic tumours presenting as large, pigmented plaques at birth or during childhood. There is a risk for malignant transformation, but no larger comprehensive studies exist and the diagnosis is challenging, especially on limited biopsy material. The aim is to describe the clinicopathological features and behaviour of the disease more comprehensively.

METHODS AND RESULTS

We retrieved eight plaque-type blue naevi, presenting as large, pigmented plaques (median = 7 cm; range = 3-26) most frequently affecting the scalp (four) followed by the cheek, arm, abdominal wall and gluteal cleft (one each), with a slight female predilection. Median age at time of biopsy was 39.5 years (range = 15-90), but three tumours had been present at birth and one since childhood. Histopathologically, the tumours were poorly circumscribed and composed of cellular fascicles of uniform spindle cells in a background of variably prominent pigmented dendritic cells affecting dermis and subcutaneous tissues. The majority had mutations in GNAQ. One tumour showed malignant transformation, characterised by an expansile nodule of pleomorphic epithelioid melanocytes with rhabdoid morphology, high mitotic activity and areas of necrosis. This patient developed metastatic melanoma to lymph nodes. All patients are alive with a median follow-up of 60 months.

CONCLUSION

Plaque-type blue naevi are diagnostically challenging tumours with risk for malignant transformation. Awareness and familiarity with the salient clinicopathological features are necessary for reliable diagnosis, and long-term clinical follow-up is required to monitor for malignant transformation.

Diagnostic Imaging of Agminated Blue Lesions and Blue Lesions with Satellitosis: Case Series with a Concise Review of the Current Literature

Background: Agmination and/or satellitosis in pigmented blue lesions is a phenomenon rarely mentioned in the literature and not well known. This phenomenon can be expressed by several benign and malignant pigmented blue lesions, such as blue nevi, Spitz nevi, melanocytoma and melanoma. On this spectrum, dermoscopy, reflectance confocal microscopy (RCM) and dynamic Optical coherence tomography (D-OCT) represent non-invasive imaging technologies, which may help clinicians in the diagnosis of melanoma and non-melanoma skin cancers in daily clinical practice. Methods: Currently, in the literature there is a lack of new data about agminated blue lesions and blues lesions with satellitosis, as well as the lack of a recent and updated review of the literature about this topic. Therefore, considering that clinicians must be confident with the diagnosis of these rare skin lesions, we decided to carry out this work. Results: In this paper, four new cases of agminated pigmented cutaneous lesions were described. Moreover, a review of the current literature on this topic was performed. Conclusions: A clinical-pathological correlation is often needed to reach a correct diagnosis; currently, dermoscopy and non-invasive diagnostic techniques, such as reflectance confocal microscopy and optical coherence tomography, due to the depth of these skin lesions in the dermis, can only make a partial and limited contribution.

GRM1 Gene Fusions as an Alternative Molecular Driver in Blue Nevi and Related Melanomas

Activating mutations in GNAQ, GNA11, CYSLTR2, and PLCB4 genes are regarded as the main oncogenic drivers of blue nevi (BN) and blue malignant melanocytic tumors. Here we report 4 cases of blue melanocytic neoplasms devoid of these mutations but harboring GRM1 gene fusions. In this short series, there was no gender predominance (sex ratio, 1). The mean age at diagnosis was 40 years (range, 12-72). Tumors were located on the face (n = 2), forearm (n = 1), and dorsum of the foot (n = 1). Clinically, a plaque-like pre-existing BN was found in 2 cases, including a deep location; another case presented as an Ota nevus. Two cases were diagnosed as melanoma ex-BN, one as an atypical BN, and one as a plaque-like BN. Microscopic examination revealed a dermal proliferation of dendritic melanocytes in a sclerotic stroma. A dermal cellular nodule with atypia and mitotic activity was observed in 3 cases. Genetic investigation by whole exome RNA sequencing revealed MYO10::GRM1 (n = 2) and ZEB2::GRM1 (n = 1) fusions. A GRM1 rearrangement was identified by fluorescence in situ hybridization in the remaining case. SF3B1 comutations were present in the 2 melanomas, and both had a MYO10::GRM1 fusion. Array comparative genomic hybridization was feasible for 3 cases and displayed multiple copy number alterations in the 2 melanomas and limited copy number alterations in the atypical BN, all genomic profiles compatible with those of classical blue lesions. GRM1 was overexpressed in all cases compared with a control group of blue lesions with other typical mutations. Both melanomas rapidly developed visceral metastases following diagnosis, with a fatal outcome in one case and tumor progression under palliative care in the other. These data suggest that GRM1 gene fusions could represent an additional rare oncogenic driver in the setting of BN, mutually exclusive of classical canonical mutations, especially in plaque-type or Ota subtypes.

Malignant melanoma associated with a plaque-type blue nevus of the cheek: a case report

Blue nevi, which are characterized by collections of pigment-producing melanocytes in the dermis, have a variety of clinicopathological characteristics. Plaque-type blue nevus (PTBN) is a variant of blue nevi. PTBN presents at birth or arises in early childhood, and it shows a combination of the features found in common blue nevus and cellular blue nevus. It is typically found on the dorsal surface of the hands and feet or on the head and neck, and it is usually benign and stable over time. However, reports have occasionally described malignant melanomas developing in or associated with a PTBN. Malignant blue nevi are most commonly found on the scalp. We report the case of an 88-year-old woman with a malignant melanoma associated with a PTBN of the cheek.

Blue naevi and the blue tumour spectrum

Blue naevi (BN) form a wide group of benign dermal melanocytic proliferations. They are genetically distinct from common and Spitz naevi with frequent hotspot mutations occurring in Gαq genes. Clinically, BN display a female predominance, elective sites of emergence and a great variety of subtypes related to specific regions of the skin linked to early embryological genetic events. Histologically, most BN are located in the dermis with small, bland, spindled and dendritic pigmented melanocytes within a fibrous background. Variation in tumour volume, fibrosis, and melanin pigment load can be broad. A growth in size and cellularity can occur within a subset of tumours as they acquire the morphological features of cellular blue naevi, with a biphasic architecture associating a dendritic blue naevus morphology near the surface, and deep vertical cellular expansions of medium-sized, bland melanocytes often reaching the subcutis. Sclerosing and myxoid variants can be observed either as individual or combined modifications that can add complexity to an otherwise straightforward diagnosis. Malignant progression of a cellular blue naevus is exceptional with an intermediate stage named atypical cellular blue naevus. Malignant blue melanomas are fast growing, large, pigmented tumours with most often obvious features of malignancy. However, they are difficult to separate from other malignant dermal melanocytic proliferations. Herein, we will extensively detail and illustrate the clinical, histological and genetic features of the vast spectrum of blue naevi and related entities in the skin.

Molecular testing in melanoma for the surgical pathologist

The diagnostic work-up of melanocytic tumours has undergone significant changes in the last years following the exponential growth of molecular assays. For the practising pathologist it is often difficult to sort through the multitude of different tests that are currently available for clinical use. The molecular tests used in melanocytic pathology can be broadly divided into four categories: (1) tests that predict response to systemic therapy in melanoma; (2) tests that predict prognosis in melanoma; (3) tests useful in determining the type or class of melanocytic tumour; and (4) tests useful in the differential diagnosis of naevus versus melanoma (primarily used as an aid in the diagnosis of histologically ambiguous melanocytic lesions). This review will present an updated synopsis of major molecular ancillary tests used in clinical practice.

Large Plaque-type Blue Nevus with GNAQ Q209P Mutation, Involving Mammary Gland Tissue: Under-Recognized Mammary Condition as an Origin of Primary Mammary Melanocytic Tumors

ABSTRACT

Plaque-type blue nevus is a rare variant of blue nevi that was first described in 1954. This article presents clinical, macroscopic, histopathological, and genetic findings for a case of large plaque-type blue nevus expanding into the mammary gland tissue as well as the skin of the right breast. A 63-year-old woman presented with a congenital, large, blue-colored macule limited to the hypochondriac area of the right breast. A nodule 8 mm in diameter was also present in the mammary gland tissue. Magnetic resonance imaging was unable to detect diffuse melanin deposition in the mammary gland tissue, but pigmentation in the whole mammary parenchyma was observed in the cut surfaces of the mastectomy specimen. Histopathology revealed a sparse distribution of dendritic melanocytes in whole sections of the mammary fibrous tissue and partial sections of the dermis. The histopathological criteria for atypical cellular blue nevus were fulfilled for the mammary tumor. Nodal blue nevus was diagnosed in the sentinel lymph node. Sanger sequencing confirmed the GNAQ Q209P mutation, which was also identified in all 4 literature cases of plaque-type blue nevus, but rarely in conventional blue nevi and uveal melanoma. It should be noted that plaque-type blue nevus can expand into the mammary gland tissue, even if the pigmented lesion does not exist on the overlying breast skin. The mammary condition can be the origin of primary mammary melanocytic tumors. Mosaicism of the GNAQ Q209P mutation can be a characteristic genetic alteration to extensive blue nevi, including plaque-type blue nevus.

Through the looking glass and what you find there: making sense of comparative genomic hybridization and fluorescence in situ hybridization for melanoma diagnosis

Melanoma is the leading cause of death among cutaneous neoplasms. Best outcome relies on early detection and accurate pathologic diagnosis. For the great majority of melanocytic tumors, histopathologic examination can reliably distinguish nevi from melanomas. However, there is a subset of melanocytic tumors that cannot be definitively classified as benign or malignant using histopathological criteria alone. These tumors are usually diagnosed using terms that imply various degrees of uncertainty in regards to their malignant potential and create the possibility for over or undertreatment. For such tumors, additional ancillary tests would be beneficial in adjudicating a more definitive diagnosis. In recent years, DNA-based molecular ancillary tests, specifically comparative genomic hybridization and fluorescence in situ hybridization, have been developed to help guide the diagnosis of ambiguous melanocytic proliferations. This study will present an updated overview of these two major ancillary tests, which are currently being used in clinical practice to assist in the diagnosis of challenging melanocytic neoplasms.

A cellular blue nevus with pigmented epithelioid melanocytoma-like pattern on the ipsilateral upper arm associated with a congenital plaque-type blue nevus on the hand

A 36-year-old man presented with a subcutaneous nodule on the right upper arm. A small nodule had developed 8 years earlier, and grew in size, accompanied by a tingling sensation and numbness. In addition, he had a bluish irregular patch on the right hand since birth, which crossed from the palm to the dorsal hand. Skin biopsies from the hand showed a heavily pigmented melanocyte proliferation in the dermis with perieccrine, perivascular, and perineural involvement, and a diagnosis of congenital plaque-type blue nevus was made. The tumor on the arm was located closely along the median nerve, and was observed as a large black pedunculated round tumor. Histopathologically, the tumor on the arm consisted of densely packed tissue with nevoid cells without atypia in the larger nodular part, and heavily pigmented spindle and epithelioid melanocytes in the slender stalk area, which was diagnosed as cellular blue nevus with pigmented epithelioid melanocytoma-like pattern. Next-generation sequencing revealed GNAQ mutations in the hand lesion, and in the lesions on the arm. This case suggests that the areas of skin following the same neural distribution of a congenital plaque-type blue nevus on the extremities should be followed up for secondary changes.

Agminated blue nevus with a GNAQ mutation: A case report and review of the literature

Agminated blue nevi are dermal melanocytic proliferations that classically present as dark blue macules or papules in a grouped, linear, or blaschkoid distribution. In their more common sporadic form, blue nevi manifest in young adulthood as solitary blue papules or macules on the scalp, face, hands, or feet. By contrast, agminated blue nevi tend to manifest earlier in life, and are distributed more evenly across anatomic sites. Recent studies have identified mutations in sporadic blue nevi in the genes encoding G Protein subunit alpha Q and G protein subunit alpha 11 (GNAQ and GNA11). It is unknown whether agminated blue nevi share the same genetic changes. In the present paper, we present a case of agminated blue nevus on the wrist, and identify an activating mutation (c.626A > T, p.Glu209Leu) in GNAQ. We hypothesize that GNAQ/GNA11 activating mutations arising earlier during development may trigger agminated blue nevi, explaining the broader field of involvement in these cutaneous lesions.

Agminated segmental plaque-type blue nevus associated with hypertrichosis and soft tissue hypertrophy: Report of a case and review of the literature

Blue nevi are common skin neoplasms that typically present as asymptomatic solitary papules, although they may rarely occur in an agminated configuration. We describe a case of agminated blue nevus in a segmental facial distribution associated with soft tissue hypertrophy and hypertrichosis in a 16-year-old boy and present a review of the literature. Although they are generally considered to be benign, concurrent soft tissue changes occurring within an agminated blue nevus should be investigated thoroughly to exclude alternate diagnoses.

Melanoma arising from a plaque-type blue naevus with subcutaneous cellular nodules of the scalp

Plaque-type blue naevus (PTBN) is a very rare variant of blue naevus (BN). The potential malignancy of subcutaneous cellular nodules (SCN) in PTBN was discovered in 2012, and there is currently no clear consensus on prognostic factors or management guidelines of such lesions. PTBN on the scalp have not been described in the literature. We report the clinical, histopathological and immunohistological features of a 50-year-old man who presented with a 30-year history of scalp PTBN, with malignant proliferation of nodular elements and fatal outcome 8 years later. This case suggests that long-term monitoring of patients with PTBN is required. Early surgical removal of such lesions should be considered, especially in the presence of any case of enlargement or change.

The long history of a melanoma associated with a congenital large plaque type blue nevus with subcutaneous cellular nodules

The term large plaque type blue nevus with subcutaneous cellular nodules (LPTBN-SN) refers to a huge blue nevus, usually located on the trunk, that develops subcutaneous nodules many years after the lesion has appeared. The potential malignancy of an LPTBN-SN was only discovered in 2012.

We report the case of a 56-year-old Caucasian man that developed a cutaneous melanoma on an LPTBN-SN of the trunk. The first diagnosis was made more than 10 years before his death due to melanoma metastasis.

The case reported here highlights the malignant potential of an LPTBN-SN, the very long course even without treatment and the possible coexistence of benign, borderline or malignant subcutaneous nodules in the same LPTBN-SN.

Patients with large congenital blue nevi should be advised on the potential oncologic transformation of these lesions, the importance of follow-ups should be emphasized and, whenever possible, a preventive complete surgical removal should be evaluated before subcutaneous nodules develop.

Atypical Spitz Tumor Arising on a Congenital Linear Plaque-Type Blue Nevus: A Case Report With a Review of the Literature on Plaque-Type Blue Nevus

The plaque-type blue nevus (PTBN) is a rare variant of blue nevus, of which only a few reports are described. A nodular growth within a preexistent PTBN should always alert to the possibility of malignant transformation. The authors report the first case of an atypical Spitz tumor arising on a congenital linear PTBN in a 60-year-old woman. The diagnosis of “atypical Spitz tumor” is here used to describe a microscopic “gray zone” in which it is not possible to differentiate with adequate certainty between a Spitz nevus and a spitzoid melanoma. This report adds to and summarizes the small body of literature describing PTBN and discusses diagnostic and clinical implications.

Melanoma arising in association with blue nevus: a clinical and pathologic study of 24 cases and comprehensive review of the literature

Melanomas arising in association with blue nevi or mimicking cellular blue nevi comprise a relatively rare and heterogeneous group of melanomas. It remains controversial which prognostic indicators predictive of outcome in conventional cutaneous melanomas are applicable to this type of melanoma. Here, we describe the clinical and histopathologic features of 24 melanomas arising in association with blue nevi and correlate these with clinical outcome. The mean patient age was 49 years (range: 23-85) with a slight female predominance (15 females:9 males). The most common anatomic locations included the head and neck region (50%), the trunk (21%), and the buttock/sacrococcygeum (17%). Histologically, the tumors were typically situated in the mid to deep dermis with variable involvement of the subcutis, but uniformly lacked a prominent intraepithelial component. The mean tumor thickness (defined as either the standard Breslow thickness or, if not available due to the lack of orientation or lack of epidermis, the largest tumor dimension) was 20.9 mm (range: 0.6-130 mm). The mean mitotic figure count was 6.5/mm(2) (range: 1-30/mm(2)). Perineural invasion was common (38%). Follow-up was available for 21 cases (median 2.1 years). The median overall survival, recurrence-free survival, time to local recurrence, and time to distant recurrence were 5.2, 0.7, 2.6, and 1.6 years, respectively. Logistic regression analyses demonstrated a significant association between tumor thickness and recurrence-free survival (hazard ratio=1.02 per mm; P=0.04) and reduced time to distant metastasis (hazard ratio=1.03 per mm; P=0.02) with a similar trend toward reduced time to local recurrence (hazard ratio=1.02 per mm; P=0.07). No other parameters (age, anatomic location, mitotic figures, lymphovascular or perineural invasion, or type of associated blue nevus) emerged as significant. In addition, we provide a comprehensive review of 109 cases of melanoma blue nevus type described in the English literature and summarize our findings in this context.

Chromosomal copy number analysis in melanoma diagnostics

The majority of melanocytic neoplasms can be correctly diagnosed using routine histopathologic analysis. However, a significant minority of tumors have ambiguous histopathologic attributes that overlap between melanocytic nevi and melanoma. Ancillary tests that assist in distinguishing potentially lethal melanomas from benign melanocytic nevi with atypical histopathologic features are available, but still need refining.Most melanomas have chromosomal copy number aberrations, frequently involving multiple chromosomes. With rare exceptions, such anomalies are not found in melanocytic nevi. This difference formed the basis to develop assays that can help distinguish melanoma from nevi by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). FISH can detect chromosomal copy number changes of a limited number of loci within individual cells. By contrast, CGH assesses copy number across the entire genome, but typically is performed on bulk cell populations so that copy number changes in individual cells or subpopulations of cells can go undetected. Both FISH and CGH have been used to provide genomic information in histopathologically ambiguous melanocytic tumors that can assist pathologists make correct diagnoses.

Large agminated cellular 'plaque-type' blue nevus surrounding the ear: a case and review

Large or giant cellular blue nevi are usually congenital and represent a challenge for the physician. Close anatomic structures may be altered by the size of the moles. In this article, we report the case of an uncommon large, agminated, cellular blue nevus of the 'plaque type' in a 42-year-old female. Due to the risks of malignant melanoma development on a large or giant blue nevus, we highlight the importance of proper histopathological diagnosis. Furthermore, because of the possibility that the nevus may invade the bone and cerebral tissues, we discuss the indication of a radiological diagnosis. The accurate correlation to clinical and histopathological findings and appropriate multidisciplinary management can save the lives of patients.