The many faces of blue nevus: A clinicopathologic study

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.

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.

Lesion- and Patient-Related Variables May Provide Additional Clues during Dermoscopic Assessment of Blue Nevi—A Retrospective Cohort Study

Simple Summary

Blue nevi (BN) are dermal dendritic melanocytic proliferations which may be congenital or acquired. Due to wide clinical and dermoscopic presentation, their diagnosis may sometimes be difficult, especially if the history of lesion occurrence is unknown. Little is known about the correlation between lesion- and patient-related variables and dermoscopic features of blue nevi. The aim of the study was to analyze dermoscopic features of blue nevi, with particular regard to structures whose prevalence has not been previously reported, and to investigate the possible influence of selected clinical variables on dermoscopic presentation. Our findings provide new insights into the dermoscopic structures observed in blue nevi and their variability according to patient’s phototype and lesion size/localization.

Abstract

Background: Little is known about the correlation between lesion- and patient-related variables and the dermoscopic features of blue nevi. The aim of the study was dermoscopic analysis of blue nevi in association with patient- and lesion-related variables, with a special interest in structures whose prevalence has not been previously reported. Methods: This was a double-center, retrospective study, which included the analysis of histopathologically confirmed blue nevi (n = 93). Results: There was no difference in the frequency of the observed dermoscopic features according to patients’ gender and age. Pink structureless areas were more common in patients with I/II Fitzpatrick skin phototypes as well as in the patients with photodamaged skin, while blue prominent skin markings over brownish/blue-gray background occurred exclusively in patients with phototype III. Structures of previously unreported prevalence in blue nevi were skin-colored circles (present in 32.3%), gray circles (2.2%), follicular ostia with no pigmentation (18.4%; present exclusively on the face), blue skin markings over brownish background (present in 18.2%; detected only on the limbs) and dark brown polygons (one lesion located on the lower extremity). Conclusion: Dermoscopic presentation of blue nevi may vary according to the patient’s phototype and lesion size/localization rather than gender and age.

Cellular blue nevus tumor presenting as a submandibular lymph node in a 16-year-old

The cellular blue nevus tumor is a type of dendritic melanocytic nevus that is typically benign and exceedingly rare. The incidence of all blue nevi is about 1%, usually affecting the adult population and appearing on the extremities, sacrococcygeal or gluteal regions. There have only been a handful of case reports cited in the literature where cellular blue nevi present in the head and neck region, usually affecting the scalp and young adult population (7, 8). As such, it is exceedingly rare to encounter a cellular blue nevus tumor in the neck or infiltrating into neck lymph nodes. Here we report a rare case of a cellular blue nevus tumor presenting as a right neck mass in a pediatric 16-year-old patient, shown to invade into the submandibular lymph node and surrounding soft tissue. It is important to be aware of the cellular blue nevus tumor as a differential diagnosis in pediatric neck masses. Histological evaluation is necessary to determine tumor aggression and malignant potential which can guide further treatment in pediatric patients.

Dermoscopic Predictors of Benignity and Malignancy in Equivocal Lesions Predominated by Blue Color

BACKGROUND

Blue color in dermoscopy can be seen in a wide range of benign and malignant lesions, melanocytic or not. Some blue-colored dermoscopic criteria have been associated with specific tumors, such as blue-white veil with melanoma and homogeneous blue with blue nevi. However, when blue color occupies a large part of the lesion's surface, the dermoscopic assessment might be particularly challenging.

OBJECTIVE

To identify dermoscopic predictors associated with benignity and malignancy in tumors characterized by a predominant dermoscopic presence of blue color.

METHODS

We retrospectively screened our institutional database for tumors exhibiting blue color in at least 50% of their surface with available histopathologic diagnosis. Lesions with blue color covering less than 50% of their extent and lesions not histopathologically assessed were excluded. The dermoscopic images were evaluated for the presence of predefined criteria, including the characteristics of the blue color, coexisting colors, and the vascular structures.

RESULTS

Of 91 included tumors, 53 were benign (35 blue nevi, 10 angiomas, and 8 seborrheic keratoses) and 38 malignant (12 melanomas and 26 basal cell carcinomas). Our analysis revealed 3 potent dermoscopic predictors of benignity: extension of blue color in more than 75% of the surface, diffuse distribution of blue color, and absence of vessels, posing a 2.3-fold, 5.6-fold, and 6.7-fold increased probability of benignity, respectively. In contrast, asymmetric distribution of blue color, blue clods, coexistence of gray color and linear vessels were significantly predictive of malignancy, posing a 8.9-fold, 2.8-fold, 13.5-fold, and 10.4-fold increased probability, respectively.

CONCLUSION

In predominantly blue tumors, the probability of malignancy is high when blue color is seen in clods or is asymmetrically distributed and when gray color or linear vessels coexist. In contrast, a diffuse distribution of blue color, its expansion in more than 75% of the surface, and the absence of vessels are highly suggestive of a benign tumor.

Blue nevus of the nail: A case report and review

Blue nevus (BN), in all its clinical variants, rarely affects the nail bed. This leads to difficulty in the diagnosis of BN within the nail bed as well as to challenges with regard to its treatment and follow-up management, not solely attributed to the intrinsic difficulty of the anatomical site. We present the first case in the literature of an acquired cellular BN entirely confined within the nail bed, in a female Caucasian patient. We propose diagnostic and therapeutic options based on personal clinical and surgical experience.

Compound blue nevus: a reappraisal of the concept in the genomic era

We report a series of 21 compound blue nevi, a rare variant in the vast clinical and morphological spectrum of blue melanocytic proliferations. Clinically, they presented in young adults, with a slight female predominance. One-third were located on the dorsum of the foot. Morphologically, all cases displayed large dendritic melanocytes restricted to the deep layers of the epidermis. The compound component was central and evenly distributed. Melanocytic density ranged from scarce isolated cells to a confluent lentiginous architecture. In 12 of the 21 cases, junctional nests of small, bland, weakly pigmented melanocytes were associated. These nests became confluent in the most cellular cases. In all cases, a dermal component was immediately present underneath, mainly of cellular blue nevus-type. All cases were genetically confirmed to harbor either a GNAQ or GNA11 hotspot mutation. This study expands the morphological spectrum of blue nevi that should not be restricted to a strictly intradermal melanocytic proliferation.

Abundance of the benign melanocytic universe: Dermoscopic-histopathological correlation in nevi

The broad universe of "melanocytic nevi" includes a variety of different subtypes, which can be classified either due to their morphology, epidemiology, genetic alterations or risk for developing melanoma. Regarding morphology, on the one hand macroscopic/clinical and on the other hand histopathological appearance were used to subdivide in the past, often resulting in confusion and poor interobserver agreement, while nowadays dermoscopy presents the clinician's precious bridge between naked-eye examination and histopathological diagnostics, allowing prediction of the lesions' histopathology, follow up and monitoring over time without need of excision. The non-invasive dermoscopic examination relies on the assessment of colors, patterns and the distribution of both within a cutaneous lesion. Until today, the correspondence of certain dermoscopic colors and patterns to certain histopathological correlates has been reported for a huge amount of different cutaneous lesions. Moreover, the correspondence of certain dermoscopic features to certain body sites, age groups and pigmentary traits, but also to specific genetic alterations in lesions, has been broadly investigated. Dermoscopy has led us to a new understanding of melanocytic nevi's biology and evolution and, last but not least, to a new classification system, which we want to present herein.

Common and not so Common Melanocytic Lesions in Children and Adolescents

The acquired melanocytic nevus is the most common lesion encountered by pediatric pathologists and dermatopathologists in their daily practice. In most cases, there are few difficulties in histopathologic diagnosis. However, it is the acquired melanocytic lesion known as the Spitz nevus, with its intrinsic atypical features which becomes the challenge since it exists along a histopathologic and biologic continuum from the atypical Spitz tumor to spitzoid melanoma. The frustration with some of these spitzoid lesions is that even the "experts" cannot agree as to the differentiation of one from the other even at the level of molecular genetics. Other melanocytic lesions are discussed including the congenital melanocytic nevus with its proliferative nodule(s) and melanoma as the ultimate complication. Although uncommon, cutaneous melanoma in the first 2 decades is emerging as a clinical problem especially in young women in the second decade of life. These are ultraviolet-associated neoplasms whose histopathologic and prognostic features are identical to the adult experience. Considerable progress has been made over the past 15 to 20 years in our understanding of cutaneous melanocytic lesions, but gaps still exist in the important group of spitzoid lesions. It can also be anticipated that more cutaneous melanomas in children will be seen in the future based upon epidemiologic studies.

Pigmented Lesions of the Nervous System and the Neural Crest: Lessons From Embryology

Neurosurgeons encounter a number of pigmented tumors of the central nervous system in a variety of locations, including primary central nervous system melanoma, blue nevus of the spinal cord, and melanotic schwannoma. When examined through the lens of embryology, pigmented lesions share a unifying connection: They occur in structures that are neural crest cell derivatives. Here, we review the important progress made in the embryology of neural crest cells, present 3 cases of pigmented tumors of the nervous system, and discuss these clinical entities in the context of the development of melanoblasts. Pigmented lesions of the nervous system arise along neural crest cell migration routes and from neural crest-derived precursors. Awareness of the evolutionary clues of vertebrate pigmentation by the neurosurgical and neuro-oncological community at large is valuable for identifying pathogenic or therapeutic targets and for designing future research on nervous system pigmented lesions. When encountering such a lesion, clinicians should be aware of the embryological basis to direct additional evaluation, including genetic testing, and to work with the scientific community in better understanding these lesions and their relationship to neural crest developmental biology.

Blue nevus and "malignant blue nevus:" A concise review

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 and histolopathologic features of common blue nevi and cellular blue nevi are discussed, as well as blue nevi with atypical features and malignant lesions with features of blue nevi.

Proposal for a clinical-dermoscopic classification of scalp naevi

BACKGROUND

Recent research suggests that scalp naevi differ with respect to their epidemiology, patient characteristics and morphological patterns, but currently a classification of scalp naevi is lacking.

OBJECTIVES

To investigate the prevalence, together with clinical and dermoscopic features, of scalp naevi detected in persons attending a skin cancer screening programme, and to elaborate a classification of scalp naevi based on their most common morphological patterns.

METHODS

Participants were recruited during the melanoma prevention programme 'sun watch' of Austrian Cancer Aid in Styria. Each participant received a clinical and dermoscopic total-body skin examination including the scalp. For each participant, demographics and clinical characteristics including number of scalp naevi were recorded. Clinical and dermoscopic photographs of at least one scalp naevus per participant were taken and evaluated for specific clinical and dermoscopic features.

RESULTS

In total 867 subjects, including 119 participants (13·7%) with scalp naevi, participated in the study. Compared with those without scalp naevi, subjects with scalp naevi were significantly younger, were more often men and more often exhibited congenital naevi on the body (P < 0·01 for all). Analysis of the clinical and dermoscopic variability of scalp naevi allowed for a proposal to classify scalp naevi into six main groups, namely common, papillomatous, eclipse, congenital, blue and atypical naevus.

CONCLUSIONS

Scalp naevi can be classified into six morphological groups; scalp lesions deviating from these six main patterns should be carefully managed to rule out melanoma.

The deep penetrating nevus

The deep penetrating nevus (DPN), also known as the plexiform spindle cell nevus, is a pigmented lesion that commonly arises on the head and neck in the first few decades of life. Histopathologically, the DPN is wedge-shaped and contains melanocytes that exhibit deep infiltration into the dermis. Given these features, DPN may clinically and histopathologically mimic malignant melanoma, sparking confusion about the appropriate evaluation and management of these lesions. The goal of this review is to summarize the clinical and histopathological features of DPN and to discuss diagnostic and treatment strategies for dermatologists.

Melanoma and satellite blue papule

The colors that are seen in dermoscopy depend on the anatomic level of the skin at which the chromophores are seen. Blue color can be found in a variety of melanocytic and nonmelanocytic lesions.

An 89-year-old man presented with a 3-year history of a slow-growing, hyperpigmented patch located on the distal third of the right arm. Dermoscopy showed an atypical network, irregularly distributed globules, pigmented internal streaks and a milky-red area. Based on these findings a diagnosis of slow-growing malignant melanoma was made. Simultaneously, a well-defined blue papule was seen on the proximal third of the same arm. Dermoscopy disclosed a homogeneous blue pattern. After clinical and dermoscopic correlation our differential diagnosis for this blue lesion included cutaneous melanoma metastasis, blue nevus and foreign body reaction. The patient recalled its onset 75 years ago after a grenade explosion. We also discuss the blue lesion appearance under reflectance confocal microscopy and high-definition optical coherence tomography. Histopathological examination after excision of the hyperpigmented patch and blue papule revealed a melanoma in situ and a foreign body reaction, respectively.

The diagnostic evaluation of a blue lesion should always rely on the integration of all data, especially clinical and dermoscopic features. Other non-invasive techniques, like reflectance confocal microscopy and high-definition optical coherence tomography can also be important aids for its differential diagnosis.

Special criteria for special locations 2: scalp, mucosal, and milk line

The anatomic region influences the dermoscopic features of different lesions. In this article, the particular characteristics of the scalp, mucosal membranes, and lesions located on the milk line are explained. In histopathology, the benign melanocytic lesions in these locations are also named nevi of special sites, considering the difficulty of the histopathologic diagnosis.

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.

Dermoscopy for the pediatric dermatologist part III: dermoscopy of melanocytic lesions

Melanocytic nevi encompass a variety of lesions, including blue, Spitz, congenital, and acquired nevi. These nevi can occasionally manifest clinical morphologies resembling melanoma, and the presence of such nevi in children can elicit anxiety in patients, parents, and clinicians. Dermoscopy has been shown to increase the diagnostic accuracy for melanoma and to help differentiate melanoma from nevi, ultimately aiding in the decision-making process as to whether to perform a biopsy. Dermoscopy is the perfect instrument to use during the evaluation of pigmented skin lesions in children because it is painless and provides important information for the clinician that can assist in formulating appropriate management decisions. This review highlights the most common benign dermoscopic patterns encountered in nevi and discuss the 10 most common dermoscopic structures seen in melanomas. Lesions manifesting a benign dermoscopic pattern and lacking any melanoma-specific structures do not need to be excised and can safely be monitored. In contrast, melanomas will invariably deviate from the benign nevus patterns and will usually manifest at least 1 of the 10 melanoma-specific structures: atypical network, negative network, streaks, crystalline structures, atypical dots and globules, irregular blotch, blue-white veil, regression structures, peripheral brown structureless areas, and atypical vessels. It is important to be cognizant of the fact that melanomas in childhood usually do not manifest the clinical ABCD features. Instead, they are often symmetric, amelanotic, nodular lesions. Although the clinical appearance may not be alarming, with dermoscopy they will invariably manifest at least one melanoma-specific structure, the most common being atypical vascular structures and crystalline structures.

Peripheral stellate telangiectasias: a clinical-dermoscopic clue for diganosing cutaneous melanoma metastases

BACKGROUND

The clinical and dermoscopic diagnosis of cutaneous melanoma metastases may be challenging especially in patients with unknown primary melanoma.

MAIN OBSERVATIONS

We observed repetitive dermoscopic patterns of peripheral stellate telangiectasias in cutaneous melanoma metastases from 3 patients, of whom 2 had an unknown primary melanoma.

CONCLUSIONS

Stellate telangiectasias surrounding bluish to purple or red nodules with recent onset may represent a clue for cutaneous melanoma metastases.

Dermoscopy of scalp tumours: a multi-centre study conducted by the international dermoscopy society

BACKGROUND

Little is known about the dermoscopic features of scalp tumours. Objective  To determine the dermoscopic features of scalp tumours.

METHODS

Retrospective analysis of dermoscopic images of histopathologically diagnosed scalp tumours from International Dermoscopy Society members.

RESULTS

A total of 323 tumours of the scalp from 315 patients (mean age: 52 years; range 3-88 years) were analysed. Scalp nevi were significantly associated with young age (<30 years) and exhibited a globular or network pattern with central or perifollicular hypopigmentation. Melanoma and non-melanoma skin cancer were associated with male gender, androgenetic alopecia, age >65 years and sun damage. Atypical network and regression were predictive for thin (≤1 mm) melanomas, whereas advanced melanomas (tumour thickness > 1 mm) revealed blue white veil, unspecific patterns and irregular black blotches or dots.

CONCLUSIONS

The data collected provide a new knowledge regarding the clinical and dermoscopy features of pigmented scalp tumours.

Angiomatoid giant cellular blue nevus of vaginal wall associated with pregnancy

Background

Blue nevi that arise from the Müllerian tract are rare melanocytic lesions. Several histopathologic variants of cellular blue nevi have been described. The angiomatoid variant is characterized by a vascular component, and is considered to be a rare variant. Few studies have explored the influence of pregnancy on melanocytic lesions.

Case

A 29-year-old woman was presented with a pigmented vaginal lesion that increased gradually during pregnancy. A full term gynecologic examination showed a tumor mass protruding into the vaginal canal. The mass was resected during cesarean-section under the clinical impression of vaginal hemangioma.

Result

Gross examination revealed a cystic mass measuring 6.0 × 4.3 × 3.5 cm, which was filled with dark friable material. Histologically, the mass showed a subepithelial cellular proliferation of heavily pigmented dendritic melanocytes with prominent vascular stroma. Cytologic pleomorphism, junctional activity, atypical mitosis, and necrosis were not found. The proliferation was immunoreactive for HMB-45, S-100 and melan-A, and non-immunoreactive for CD34, smooth muscle actin, and AE1/AE3. The MIB-1 proliferative index was less than 1%. The patient had a postoperative course without complication.

Conclusions

Angiomatoid giant cellular blue nevus arising from the vagina during pregnancy is extremely rare. The low proliferative index and absence of cytologic pleomorphism, or necrosis, supports a benign biological behavior. Clinical follow-up showed no evidence of recurrence at one year after the resection of the mass.

Blue Nevi and Related Tumors

Blue nevi and related lesions are characterized by the proliferation of dermal dendritic melanocytes. Although they share certain common clinical and histologic features, they encompass a spectrum of lesions ranging from benign melanocytic hamartomas and common blue nevi to borderline malignant pigmented epithelioid melanocytoma and aggressive malignant blue nevi. This article succinctly describes the common dermal dendritic proliferations and updates readers on newly classified entities and variants. The differential diagnosis of the main entities and strategies to distinguish them from their melanocytic and nonmelanocytic mimics is also presented.

Using dermoscopic criteria and patient-related factors for the management of pigmented melanocytic nevi

OBJECTIVE

To review recent dermoscopy studies that provide new insights into the evolution of nevi and their patterns of pigmentation as they contribute to the diagnosis of nevi and the management of pigmented melanocytic nevi.

DATA SOURCES

Data for this article were identified by searching the English and German literature by Medline and Journals@Ovid search for the period 1950 to January 2009.

STUDY SELECTION

The following relevant terms were used: dermoscopy, dermatoscopy, epiluminescence microscopy (ELM), surface microscopy, digital dermoscopy, digital dermatoscopy, digital epiluminescence microscopy, digital surface microscopy, melanocytic skin lesion, nevi, and pigmented skin lesions. There were no exclusion criteria.

DATA SYNTHESIS

The dermoscopic diagnosis of nevi relies on the following 4 criteria (each of which is characterized by 4 variables): (1) color (black, brown, gray, and blue); (2) pattern (globular, reticular, starburst, and homogeneous blue pattern); (3) pigment distribution (multifocal, central, eccentric, and uniform); and (4) special sites (face, acral areas, nail, and mucosa). In addition, the following 6 factors related to the patient might influence the pattern of pigmentation of the individual nevi: age, skin type, history of melanoma, UV exposure, pregnancy, and growth dynamics.

CONCLUSIONS

The 4 x 4 x 6 "rule" may help clinicians remember the basic dermoscopic criteria of nevi and the patient-related factors influencing their patterns. Dermoscopy is a useful technique for diagnosing melanocytic nevi, but the clinician should take additional factors into consideration to optimize the management of cases of pigmented lesions.

Equine skin tumours in 20 horses resembling three variants of human melanocytic naevi

Melanocytic tumours are important in horses, especially grey horses. Intradermal common melanocytic naevi, cellular blue naevi and combined cellular blue naevi are subgroups of human melanocytic tumours, which have not been reported in horses. In this study, we describe 20 horses with skin tumours similar to these naevi of humans. These tumours represented individual skin masses in male and female horses of different breeds. Tumours resembling human intradermal common melanocytic naevi were noted in 12 horses aged between 2 and 17 years. Seven horses aged between 4 and 15 years developed cutaneous lesions similar to human cellular blue naevi. A combined cellular blue naevus-like tumour was diagnosed in a 20-year-old horse. All tumour types formed expansile, well-demarcated, non-encapsulated, symmetrical masses. Tumours similar to intradermal common melanocytic naevi were composed of nests of round and spindeloid neoplastic cells, often embedded in myxomatous stroma. Lesions resembling cellular blue naevi were formed by intradermal bundles of ovoid to elongated cells separated by collagen fibres. The combined cellular blue naevus-like tumour resembled human cellular blue naevus with in addition, an overlying junctional common melanocytic naevus. Neoplastic cells in all groups contained varying amounts of melanin pigment and were immunopositive for S100. These equine skin tumours differ from the commonly recognized equine melanocytic tumours by their cytomorphological features, random location and the absence of an increased tumour frequency in grey horses. The resemblance of these tumours to three distinct subgroups of human naevi expands the complexity of equine proliferative cutaneous melanocytic lesions.