Immunohistochemical Expression of Lymphatic Endothelial Markers in Blue Rubber Bleb Nevus Syndrome.

INTRODUCTION: Blue rubber bleb nevus syndrome (BRBNS) is an uncommon vascular anomaly characterized by multifocal cutaneous, visceral, and other soft tissue or solid organ venous malformations. We observed that BRBNS lesions express immunohistochemical markers of lymphatic differentiation. METHODS: BRBNS histopathologic specimens assessed at our institution during the past 27 years were reviewed. Slides from 19 BRBNS lesions were selected from 14 patients (9 cutaneous, 9 gastrointestinal, and 1 hepatic). We recorded the involved anatomical compartments and presence/absence of thrombi or vascular smooth muscle. Immunohistochemical endothelial expression of PROX1 (nuclear) and D2-40 (membranous/cytoplasmic) was evaluated semi-quantitatively. RESULTS: Endothelial PROX1 immunopositivity was noted in all specimens; the majority (89.5%) demonstrated staining in more than 10% of cells. D2-40 immunopositivity was present in one-third (33%) of cutaneous lesions and only 1 gastrointestinal lesion. CONCLUSION: Endothelial cells in BRBNS almost always express 1 or more immunohistochemical markers of lymphatic differentiation.

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.

PRAME and LEF1 in Combined Deep Penetrating Nevus and Combined Blue Nevus: Utility and Pitfalls.

ABSTRACT: Deep penetrating nevi (DPN), particularly those showing combined features, or combined deep penetrating nevi (CDPN), may show histopathological resemblance to blue nevus (BN) and melanoma. Preferentially Expressed Antigen in MElanoma (PRAME) is a marker that helps distinguish melanoma from benign melanocytic lesions. Lymphoid enhancer-binding factor 1 (LEF1) has been proposed to be used in conjunction with ß-catenin for diagnosis of DPN. The immunohistochemical expression of PRAME and LEF1 was evaluated in 10 DPN (including 6 CDPN and 2 DPN-like proliferations with atypical features), 16 BN (including combined and cellular BN), and 2 melanomas with features of DPN or BN. PRAME was negative in most DPN (n = 10/10, n = 9/10, one case with discrepancy between readers) and all BN (n = 16/16), while the 2 melanomas included were positive (n = 2/2). All DPN were positive for LEF1 (n = 9/9) while only a subset of BN were positive (n = 6/16, P = 0.0028; n = 5/16, P = 0.001, per both readers). LEF1 seemed to be easier to interpret than ß-catenin because of its nuclear pattern of expression. The expression of LEF1 in the regular nevus component of combined BN presents a potential pitfall in practice because it may lead to misinterpretation of LEF1 as positive in the BN component of the lesion. However, a subset (approximately one-third) of combined BN seemed to show true LEF1 expression. Taking into account pitfalls in interpretation, the combinatorial panel of PRAME and LEF1, in addition to conventional histopathological features, may be useful to distinguish CDPN from combined BN and other benign and malignant mimics.

Melanoma arising in plaque-type blue nevus and dermal melanocytosis: Diagnostic and prognostic value of BAP1. / Melanoma sobre nevus azul en placa o sobre melanocitosis dérmicas: utilidad diagnóstica y pronóstica del BAP1.

Melanoma arising in blue nevus, also known as melanoma ex blue nevus, is a specific form of melanoma whose genetic profile is different to that of other cutaneous melanomas and surprisingly similar to that of uveal melanoma. Although melanoma ex blue nevus can appear de novo, it usually arises in a preexisting blue nevus or dermal melanocytosis. Not all nodular lesions arising in association with blue nevus or dermal melanocytosis are melanomas, however, and because clinical and histologic findings may be insufficient for a definitive diagnosis, additional studies such as comparative genomic hybridization are important. Detection of chromosomal aberrations supports a diagnosis of malignancy. Studies of the BAP1 gene are particularly useful in this setting because loss of expression is indicative of melanoma. We present 3 cases on the spectrum of blue nevus to melanoma ex blue nevus that were studied using molecular biology techniques.

Surgical considerations for spinal epidural hematoma evacuation in the setting of blue rubber bleb nevus syndrome in a child.

Blue rubber bleb nevus syndrome (BRBNS) is a rare condition that presents with venous malformation blebs throughout the body, most commonly on the skin and gastrointestinal tract. There have only been a limited number of reports of benign BRBNS lesions involving the spine in children, which were detected after chronic symptomatology. We herein present a unique case of a ruptured BRBNS venous malformation into the epidural space of the lumbar spine in a child presenting with acute neurologic deficit and discuss the relevant surgical considerations for operating in the setting of BRBNS.

Blue Nevus Hidden within the Nevus of Ota.

A 3-year-old boy presented with bluish patch and scattered blue spots on the left side of his face. After several sessions of laser treatment, the azury patch in the periorbital area became even darker. Histopathology showed many bipolar, pigment-laden dendritic cells scattered in the papillary and upper reticular dermis. Immunohistochemically, these cells were positive for S100, SOX-10, melan-A, P16, and HMB-45. The positive rate of Ki-67 was less than 5%. Finally, the lesion was diagnosed with nevus of Ota concurrent with common blue nevus. Therefore, for cases of the nevus of Ota with poor response to laser treatment, the possible coexisting diseases should be suspected.

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.

Analysis of dermoscopic changes of blue nevi on digital follow-up: A 21-year retrospective cohort study.

BACKGROUND: Blue nevi are benign dermal melanocytic proliferations that are often easy to recognize clinically. Rarely, these lesions can display atypical features, suggesting the presence of a malignant blue nevus or mimicking cutaneous metastases of melanoma. OBJECTIVE: To describe the clinical evolution of blue nevi over time and to assess the need for monitoring these lesions. METHODS: We conducted a retrospective cohort study of 103 patients who were followed between December 1998 and November 2019. An artificial intelligence algorithm was used to identify blue nevi from the databases of two digital epiluminescence devices. Changes in the area of each lesion were calculated with a segmentation neural network. RESULTS: We included 123 blue nevi from 103 patients. Most of the lesions segmented, 99 (91.7%), were considered stable. Of the 9 (8.3%) growing blue nevi identified, 2 (1.85%) showed significant growth. The studied growing blue nevi turned out to be cellular blue nevi, presented with a low tumour mutation burden and GNAQ c.626A>T alteration was identified in both lesions. LIMITATIONS: Some clinical variants of blue nevi might not be included. CONCLUSIONS: Most blue nevi remain stable during their evolution. Rarely, they can show progressive growth, although histopathological or molecular signs of malignancy have not been identified.

Melanoma arising in extracutaneous cellular blue naevus: report of two cases with comparison to cutaneous counterparts and uveal melanoma.

AIMS: Blue naevi are benign melanocytic lesions that typically occur in the dermis. Melanoma arising in blue naevus is rare, and shows a molecular profile distinct from conventional forms of cutaneous melanoma and more similar to uveal melanoma and central nervous system (CNS) melanocytomas. In contrast to conventional cutaneous melanoma, these tumour types typically show activating driver mutations in GNAQ or GNA11, a low mutational burden without evidence of a UV signature and a reproducible pattern of chromosomal copy number changes. Blue naevi can also occur at extracutaneous sites. Here we report two cases of melanoma arising in extracutaneous blue naevus and compare their molecular features to cohorts of melanoma arising in cutaneous blue naevus (five patients) and uveal melanoma (six patients). METHODS AND RESULTS: We describe the clinical, histomorphological, immunohistochemical and molecular findings in these two cases of melanoma arising in extracutaneous blue naevus. We compare their molecular profiles to melanomas arising in cutaneous blue naevus and uveal melanoma using a targeted next-generation DNA sequencing platform and find striking similarities between all three groups. CONCLUSIONS: The close relationship between blue naevus-associated melanomas, regardless of their anatomical site, supports and validates the concept of melanoma arising in extracutaneous blue naevus and suggests that the two groups share common pathogenic mechanisms. The similarity of both groups to uveal melanoma in turn supports the close relationship between blue naevus-associated melanoma, uveal melanoma and CNS melanocytoma, and their distinction from conventional UV-associated melanoma. These findings have important implications for prognosis and therapy.

A case of proliferative nodule arising within blue nevus.

Abstract: Blue nevi are a heterogeneous group of lesions that can display a variety of different clinicopathological characteristics. Although attempts are made to classify each lesion into defined subtypes, there can be overlap between the subtypes. The clinical , dermoscopic and histolopathologic features of a case of proliferative nodule arising within blue nevus is discussed. Running title: Blue nevi are an heterogeneous group of melanocytic lesions blue tinctorial properties. Proliferative nodules are rare benign lesions often present at birth as a component of a large congenital melanocytic nevi, congenital or acquired nevi. We first report a case of proliferative nodule arising within blue nevus.

Comprehensive Clinical, Histopathologic, and Molecular Analysis and Long-term Follow-up of Patients With Nodal Blue Nevi.

Blue nevi are benign, melanocytic neoplasms that show a range of clinical and morphologic patterns and include common/dendritic, cellular, and atypical cellular subtypes. Like other nevi, they most commonly occur in skin but can occasionally involve lymph nodes where they may be misinterpreted as representing metastatic melanoma. Moreover, whether benign blue nevi can metastasize to lymph nodes and their natural history and prognostic significance has been the subject of great controversy. To date, few cases of nodal blue nevi have been reported in the literature, and those reports have had limited clinical follow-up and supporting molecular data. This study sought to determine the clinical, pathologic, and molecular features of blue nevi involving lymph nodes, clarify their clinical significance, provide evidence for understanding their pathogenesis, and highlight potential pitfalls in the interpretation of lymph nodes with an ultimate aim of improving patient care. Thirteen cases of blue nevi involving lymph nodes were identified in the archives of Royal Prince Alfred Hospital, Sydney, Australia (1984-2018). A detailed assessment of the clinical and pathologic features of each case was performed, including an evaluation of all available immunohistochemical stains. Extended clinical follow-up was available for 9 patients. Droplet digital polymerase chain reaction for GNAQ Q209L, Q209P and GNA11 Q209L mutations was performed on 7 cases of blue nevi within lymph nodes together with matching cutaneous (presumed primary) blue nevi in 2 cases. All cases showed typical histologic features of blue nevi. BAP1 was retained in all cases (n=7). There were no recurrence or metastasis of blue nevus in any case on long-term clinical follow-up (n=9, median follow-up, 12 y). The majority of cases (n=5 of 7 evaluated) had GNAQ and GNA11 driver mutations. The 2 patients with a matched primary cutaneous blue nevus and regionally associated nodal blue nevus had the same GNAQ Q209L mutation in both sites in each patient. We conclude that blue nevi can involve lymph nodes and are associated with benign clinical behavior, and probably represent so-called "benign" metastasis. Awareness of these lesions is important when evaluating lymph nodes to avoid misdiagnosis as metastatic melanoma.

Blue nevi of the palpebral conjunctiva: report of 2 cases and review of literature.

PURPOSE: To describe two patients with blue nevi of the palpebral conjunctiva and to review the existing literature on common and cellular blue nevi of the conjunctiva. METHODS: Report of two cases and literature review. RESULTS: We present two cases of blue nevi in the palpebral conjunctiva: an atypical cellular blue nevus of the left upper eyelid and a common blue nevus around the lacrimal punctum of the left lower eyelid. Both patients underwent full thickness eyelid excision with wide margins. There was no tumor recurrence at 11 and 4 months postoperatively. CONCLUSIONS: Blue nevi are a group of melanocytic tumors that rarely involve the ocular adnexa. They may arise in the palpebral conjunctiva and should be considered in the differential diagnosis of pigmented lesions in this location as they can mimic melanoma.

Attempting to Solve the Pigmented Epithelioid Melanocytoma (PEM) Conundrum: PRKAR1A Inactivation Can Occur in Different Genetic Backgrounds (Common, Blue, and Spitz Subgroups) With Variation in Their Clinicopathologic Characteristics.

Pigmented epithelioid melanocytoma is a rare cutaneous melanocytic proliferation considered high-grade melanocytoma in the 2018 WHO Classification of Skin Tumors. Little has been reported about the associated genetic drivers in addition to BRAF and MAP2K1 mutations or PRKCA gene fusions. Here, we present a series of 21 cases of PRKAR1A -inactivated melanocytic tumors in which we could assess the associated genetic background. We identified 9 different driver genes related to the common, Spitz, blue nevi, and PRKC -fused groups. Nine cases were associated with a canonical BRAF p.V600E mutation, a hallmark of the common nevus group. They occurred mainly in young adults. All were combined (biphenotypic) cases with a variable proportion of compound nevus. The pigmented epithelioid melanocytoma component was made of thin fascicules or isolated epithelioid cells covered by a dense hyperpigmented melanophage background and was predominantly located in the upper dermis. One such case was malignant. Six cases were associated with Spitz-related genetic anomalies ranging from HRAS or MAP2K1 mutations to gene fusions involving MAP3K8 , MAP3K3 , and RET . They occurred mainly in children and young adults. Morphologically, they showed large confluent junctional nests in a hyperplastic epidermis and a fascicular dermal component of spindled and epithelioid melanocytes with a frequent wedged silhouette. Intravascular invasion was observed in 4/6 cases. Five cases were associated with canonical mutations of the blue nevus group with 4 CYSLTR2 p.L129Q and 1 GNAQ p.Q209L mutations. They were removed mainly in adults and showed a frequent junctional component with epidermal hyperplasia. The dermal component showed dense fascicules of spindled and epithelioid melanocytes predominating over melanophages. One case occurred in a PRKCA -fused tumor in an adolescent with classic morphologic features. These results could potentially shift the concept of PRKAR1A -inactivated melanocytoma, changing from a rather unified model to a more complex one, including genetic subgroup variations with clinical and morphologic specificities. The genetic background of PRKAR1A -inactivated melanocytic tumors should be systematically explored to better understand the extent and clinical behavior of these complex lesions.

Blue rubber bleb nevus syndrome in a Pakistani child: A case report and regional literature review.

Blue rubber bleb nevus syndrome (BRBNS) is a rare disorder in which there is development of multiple venous malformations and haemangiomas in the skin and visceral organs. The lesions mostly involve the skin and gastrointestinal systems but other organs, including the liver, muscles, and the central nervous system, can also be involved. If untreated, affected individuals develop severe anaemia. Most cases are managed with iron supplementation and blood transfusions but some may require surgical resection, endoscopic sclerosis and laser photocoagulation. Here, we present a case of BRBNS in a four-year-old girl with multiple cutaneous lesions, melena and severe anaemia. Review of South Asian literature showed that only two cases (besides ours) have been reported from Pakistan and the rest were from India. This highlights the lack of awareness of BRBNS among physicians in Pakistan and the rest of South Asian countries.

Diagnosis of the origin of an epibulbar melanocytic tumor with molecular genomics.

BACKGROUND: Uveal melanoma (UM) and conjunctival melanoma (CM) are distinct entities with different etiologies and genetic background. We present a case of an atypical subconjunctival melanoma arising from a blue nevus. PATIENTS AND METHODS: A 61-year-old female presented with a partially melanocytic epibulbar mass with surrounding episcleral pigmented spots. The lesion was detached from the overlying conjunctiva without an intraocular component. Excisional biopsy revealed a predominantly epithelioid melanoma, that was suggested to be metastasic, although there was no evidence of a primary melanoma elsewhere. RESULTS: Molecular analysis identified GNAQ and BAP1 pathogenic variants, which strongly suggested the diagnosis as a primary epibulbar melanoma arising from episcleral blue nevus. CONCLUSION: This case demonstrates the value of tumor molecular analysis using Next Generation Sequencing (NGS) for differentiating the origin of an unusually located ocular melanoma.

Novel CD63-PRKCB fusion in a case of pigmented epithelioid melanocytoma.

Pigmented epithelioid melanocytoma (PEM) is an intermediate-grade melanocytic tumor with considerable histologic overlap with other melanocytic neoplasms such as epithelioid blue nevus (EBN), which is associated with the neoplastic syndrome Carney complex (CC). Next-generation sequencing is a valuable tool for identifying the primary drivers of melanocytic neoplasms and differentiating them from one another. While germline variants in the protein kinase cAMP-dependent regulatory type 1 alpha (PRKAR1A) gene have been associated with EBN and CC, fusions in protein kinase C-alpha (PRKCA) have been shown as sporadic drivers of PEM. Herein, we report the diagnosis and workup of a case of pigmented epithelioid melanocytoma with a novel protein kinase C-beta (PRKCB) fusion.

Blue nevus with smooth muscle hyperplasia: A rare hamartoma.

A limited number of distinct histopathological variants of blue nevus exist, and hamartomatous proliferations involving melanocytic components, dendritic, or otherwise, have also been described. Blue nevus/smooth muscle hamartomas represent a rarely described entity. In this paper, we add two examples of this unusual hamartoma to the existing literature. These additional blue nevus/smooth muscle hamartomas occurred on the left mid-upper back of a 50-year-old woman and the central upper back of a 54-year-old man. Both lesions were clinically atypical pigmented lesions. Histopathologic review of both specimens revealed proliferations of predominantly spindled and pigmented dermal melanocytes with associated smooth muscle hyperplasia, compatible with blue nevus/smooth muscle hamartoma. Both specimens were accompanied by subtle changes suggesting follicular induction, a phenomenon previously described as occurring in a minority of specimens. A brief re-examination of recently diagnosed blue nevus at our institution did not reveal any additional cases in which a subtle smooth muscle component had been missed, suggesting this type of hamartoma is, indeed, exceedingly rare.