Naevus vascularis mixtus and mixed vascular naevus syndrome

Naevus vascularis mixtus (NVM), or mixed vascular naevus (MVN), is a binary phenotype resulting from allelic twin spotting, consisting of a naevus anaemicus paired with a telangiectatic naevus reminiscent of naevus roseus, and caused by a mosaic GNA11 mutation. MVN syndrome is characterized by an NVM associated with soft tissue hypotrophy or central nervous system abnormalities, mainly involving the cerebral vasculature. The differential diagnoses of NVM and its syndrome include vascular twin naevi, syndromes featuring naevus flammeus and other port‐wine naevi, and the various types of phacomatosis pigmentovascularis. NVM and MVN syndrome are rare but probably underdiagnosed and under‐reported.     

Segmental hypomelanosis and hypermelanosis arranged in a checkerboard pattern are distinct naevi: flag‐like hypomelanotic naevus and flag‐like hypermelanotic naevus

The categorization of congenital hypo‐ or hyperpigmented skin lesions following a segmental pattern has been a long‐lasting matter of debate and have been reported under various and often incorrect terms. To reassess published hypomelanotic and hypermelanotic lesions that did not follow Blaschko lines nor a phylloid pattern of mosaicism, we carried out an extensive and critical review of the worldwide literature. Seventy‐four retrieved cases consisted of lateralized hypomelanotic lesions arranged in a flag‐like pattern or appearing as large patches of grossly oval or angulated shape and sharp, serrated margins. Sometimes lesions harboured maculopapular melanocytic naevi or cooccurred with other segmentally arranged naevi. A probably non‐random association with extracutaneous anomalies was also reported on rare occasions. In 70 cases, lateralized hypermelanotic patches were arranged in a flag‐like pattern that often appeared as large quadrangular patches. Sometimes lesions harboured Spitz naevi. Ten cases belonged to phacomatosis melanorosea, whereas several others were part of so far uncategorized cases of phacomatosis pigmentovascularis. Flag‐like hypomelanosis is a distinct naevus type, for which the term ‘flag‐like hypomelanotic naevus’ is suggested. Its cooccurrence with extracutaneous abnormalities might represent a specific syndrome. Flag‐like hypermelanosis is a distinct naevus type, for which the term ‘flag‐like hypermelanotic naevus’ is suggested. Its co‐occurrence with naevus roseus defines phacomatosis melanorosea. Flag‐like hypermelanotic naevus should be distinguished from the checkerboard‐like areas of darker skin as observed in chimaeras.     

New insights in naevogenesis: number, distribution and dermoscopic patterns of naevi in the elderly

Background/Objectives: It is well recognized that the number and patterns of acquired melanocytic naevi vary with age, but little is known about naevus patterns in the elderly. This is a cross‐sectional study assessing the prevalence, dermoscopic pattern and anatomical distribution of naevus subtypes in a stratified cohort aged between 60 and 89 years. Methods: Fifty‐nine patients who attended the Queensland Institute of Dermatology were recruited randomly and evenly distributed into three age groups: 60–69 years; 70–79 years; and 80–89 years. For each participant, total naevus count and morphological naevus types were recorded with respect to age, sex and anatomical location. Flat (Clark's) naevi were further subclassified according to the dermoscopic pattern as reticular, globular or structureless. Results: Using non‐parametric methods, naevus counts in the elderly decreased due to the disappearance of reticular naevi (P < 0.05). By contrast, structureless and intradermal (Unna's and Miescher's) naevi seemed to persist even into older age. Naevi on the trunk, limbs, head and neck represented 57.6%, 31.0% and 11.3%, respectively. Notably, no reticular naevi were found on the head and neck area. Conclusions: There is a progressive reduction in total naevus counts with advancing age with respect to a cohort aged greater than 60 years.     

A curious serendipitous finding: Spitz naevus combined with a syringoma

Combined tumours are often a serendipitous finding. Among the spectrum of melanocytic tumours, the co‐existence of different cell populations of the same linage is a well‐recognised phenomenon. Less commonly documented, but still well documented is the event of a melanocytic tumour in collision with an epithelial benign or malignant neoplasm. Exceptionally infrequent is however the collision of a Spitz naevus with an epithelial tumour. Here we report the clinical‐dermoscopic and histopathological findings of a Spitz naevus occurring in collision with a syringoma.     

Malignant amelanotic melanoma developing from an intradermal naevus in a patient with oculocutaneous albinism

A 43‐year‐old Taiwanese man who had oculocutaneous albinism type 1 presented with a tumorous lesion over the pubic region. Within the tumour, there was a small pinkish plaque. Histopathologically, the tumour revealed benign naevus cells in the upper dermis and atypical malignant tumour cells in the deeper dermis. Immunohistochemistry using HMB‐45 showed intensive positive staining in the deeper dermal tumour cells. Amelanotic malignant melanoma (MM) originating from a pre‐existing intradermal naevus was diagnosed.     

Melanocytic naevi clustered on normal background skin

Several types of maculopapular melanocytic naevi can occur in a multiple form, and be arranged in a nonrandom fashion on the skin. The most frequently reported segmentally grouped naevi are lentigines. Two types of segmentally arranged lentigines probably exist. The first is associated with neurofibromatosis (NF)1 or NF1 signs, features scattered light‐brown lesions and can be considered a type of mosaic NF1. By contrast, non‐NF1 associated lesions are characterized by densely packed, dark lesions, and can be defined as ‘non‐NF1 checkerboard‐arranged lentigines’. Blue naevi, Spitz naevi and common acquired melanocytic naevi can occur, clustered in an agminated (or cannonball) shape. However, if large enough, they always follow a checkerboard pattern. Hence, such mosaic conditions should be termed ‘checkerboard‐arranged blue naevi’, ‘checkerboard‐arranged Spitz naevi’ and ‘checkerboard‐arranged common acquired melanocytic naevi’. Segmentally arranged dysplastic melanocytic naevi probably represent a mosaic form of dysplastic naevus syndrome. Dysplastic melanocytic naevi confined to a cutaneous segment could be defined as ‘isolated segmental dysplastic naevus syndrome’, while segmentally arranged dysplastic melanocytic naevi co‐occurring with widespread, nonsegmental dysplastic melanocytic naevi might configure a ‘superimposed segmental dysplastic naevus syndrome’. Small congenital melanocytic naevi are always grouped along Blaschko lines. The only other instances following Blaschko lines are the so‐called ‘linear lentiginous naevus’ and a unique case of multiple deep penetrating naevi.     

BAP1‐inactivated melanocytic tumour with borderline histopathological features (BAP1‐inactivated melanocytoma): A case report and a reappraisal

We describe a case of BRCA1‐associated protein (BAP1)‐inactivated melanocytic tumour (BIMT) in a 22‐year‐old woman, documenting for the first time with dermoscopy its sudden development with the onset of an atypical vascular pattern within a Miescher naevus. The tumour was histopathologically atypical because of the presence of confluent pleomorphism, solid sheets of cells and grouped mitotic figures: these features were consistent with a melanocytic neoplasm with intermediate morphology (‘BAP1‐inactivated melanocytoma’; BIM) between a BAP1‐inactivated melanocytic naevus and a BAP1‐inactivated melanoma. The atypical histopathological features of the present case were different from the criteria quoted for BIM in the World Health Organization 2018 classification of skin tumours.     

Mucinous eccrine naevus: case report and review of the literature

Mucinous eccrine naevus (MEN) is an extremely rare variant of eccrine naevus. There are only nine reported cases in the English literature. We report a 3‐month‐old boy with a congenital lesion on the lower back, and review the other cases in the literature. In most cases, MEN presents before puberty. The commonest presentation is a unilateral, solitary, brownish nodule without hyperhidrosis occurring on the legs. The diagnosis of this condition is confirmed by the characteristic histopathological features. Treatment options may be considered if symptomatic.     

Cytoplasmic β‐catenin is lacking in a subset of melanoma‐associated naevi,but is detectable in naevus‐associated melanomas: potential implications for melanoma tumorigenesis?

Summary Background An excess of intracellular β‐catenin protein is triggered by various genetic alterations in melanoma cell lines, and has been suggested to play a role in melanoma tumorigenesis. Objectives To investigate the role played in vivo by β‐catenin in melanoma tumorigenesis, we compared the cytoplasmic detection of β‐catenin in benign melanocytic cells vs. malignant melanoma cells presumably generated from these benign melanocytic cells. For this purpose, melanocytic naevi occurring in association with melanoma, which were suggested to be melanoma precursors, were compared with their associated melanoma for β‐catenin cytoplasmic immunoreactivity. Methods Fifty‐seven consecutive cases of primary cutaneous melanoma were considered, and 15 of them were found to be associated with a melanocytic naevus portion. The naevus portion showed features of acquired melanocytic naevus (total 12 cases: five dysplastic, seven intradermal) or congenital growth pattern naevus (total three cases: one superficial, two deep). All specimens were immunohistochemically investigated for β‐catenin. Results Virtually all primary cutaneous melanomas, including those associated with a naevus portion, showed cytoplasmic β‐catenin positivity. However, the intradermal naevus portion was consistently cytoplasmic β‐catenin negative, while both the dysplastic and the congenital naevus portions were cytoplasmic β‐catenin positive. Conclusions β‐Catenin excess may play a role in melanoma tumorigenesis, because β‐catenin cytoplasmic reactivity was found in primary cutaneous melanoma but not in its associated intradermal naevus precursor. As, however, β‐catenin cytoplasmic reactivity was detected not only in primary cutaneous melanoma but also in its associated dysplastic/congenital naevus precursors, β‐catenin stabilization alone is not sufficient to play a decisive role for melanoma onset.     

Large plaque‐type blue naevus with subcutaneous cellular nodules

We report a new case of ‘large plaque‐type blue naevus (PTBN) with subcutaneous cellular nodules’ involving the breast. A 25‐year‐old‐woman presented with a large plaque, 140 × 100 mm in size, on the right chest wall involving the right breast, associated with recent subcutaneous nodules. Histopathological examination revealed features of cellular and common blue naevus. Dermatoscopy was performed, and the diagnosis of PTBN was made. PTBN is a rare condition with an imprecise prognosis. In cases of PBTN lesions on the head, clinicians must keep in mind the risk of malignant transformation of PTBN or an association with cutaneous neurocristic hamartoma. For this new variant of PTBN appearing on the trunk, we propose close monitoring of the patient if surgical excision is impossible.     

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.     

Late‐onset bulky naevocytoma of the perineum masquerading as a malignant melanoma

Bulky naevocytoma of the perineum is a very rare variant of giant congenital melanocytic naevus (GCMN). It presents as a bulky naevocytic tumour in the perineal region with characteristic histological findings, such as extensive areas with a neural appearance called ‘lames foliacees’, formation of a pseudofollicular structure and extension of naevus cells between collagen bundles in a row called ‘Indian‐file’ pattern. We report a case of late‐onset bulky naevocytoma of the perineum in a 13‐year‐old girl. The patient presented with two bulky, pedunculated, heavily pigmented masses in the vulvar area that developed in a pre‐existing GCMN lesion, which began around puberty and caused severe gait disturbance. Given the possibility of malignant transformation, we conducted staged reduction surgery of the tumour masses, which were found to be intradermal naevi without evidence of malignancy. The patient's gait disturbance improved markedly after surgery.     

Lichen planopilaris after imiquimod 5% cream for multiple BCC in basal cell naevus syndrome

Basal cell naevus syndrome is an inherited autosomal dominant genetic disorder characterised by multiple basal cell carcinomas (BCC), skeletal, neurological and opthalmological abnormalities. The treatment of choice of the often multiple and large BCC consists of a combined approach including surgery, liquid nitrogen and other topical treatment modalities. Imiquimod 5% cream is an immune–response‐modifying drug with antiviral and anti‐tumour activity. Recent reports have associated the immune‐stimulant properties of imiquimod with the exacerbation of several autoimmune skin diseases, such as eczema, psoriasis, vitiligo and lichenoid dermatitis. Here we report a patient with basal cell naevus syndrome who developed a lichen planopilaris on the same site of the scalp, which had been previously treated with two cycles of imiquimod for multiple BCC.     

Outdoor sports and risk of ultraviolet radiation-related skin lesions in children: evaluation of risks and prevention

Background Excessive ultraviolet (UV) radiation exposure can cause skin cancers, skin photoageing and cataracts. Children are targeted by sun‐protection campaigns because high sun exposure and sunburn in childhood increase the risk of melanoma in adulthood. Little information is available about UV radiation risk and exposure in children who take part in outdoor sports. Objective To evaluate the risk of developing UV radiation‐induced skin lesions run by children who practise outdoor sports, and UV radiation exposure and sun‐protection measures during a soccer tournament. Methods Firstly, we evaluated the relationship between melanocytic naevus – a skin lesion linked with exposure to UV radiation – and outdoor sports in 660 11‐year‐old children. Secondly, we used the occasion of a 1‐day soccer tournament held in the spring to evaluate UV radiation‐protective measures used by soccer players and the public. We also evaluated the UV radiation index and cloud cover during the tournament, and calculated the UV radiation dose and minimal erythema dose depending on skin phototype. Results The naevus count and acquired naevus count measured over the 2 years of the study were higher in the 344 children who practised outdoor sports. Sun‐protective measures were insufficient for soccer players and the public. Conclusions This study shows that outdoor sports increase the risk of developing UV radiation‐induced skin lesions in childhood. During a 1‐day soccer tournament held in the spring, children and their parents were inadequately protected against the sun. These results suggest that sun‐protection campaigns should be aimed at children who practise popular outdoor sports.     

Dermoscopic naevus patterns in people at high versus moderate/low melanoma risk in Queensland

Introduction: Dermoscopic understanding of naevus characteristics is essential baseline knowledge for identifying early malignant changes. Method: This cross‐sectional study includes 34 patients (56% female, mean age 48 years) at high risk of melanoma (personal or a first degree family member with history of melanoma) and 31 moderate/low melanoma risk volunteers (55% female, mean age 37 years) recruited at the Princess Alexandra Hospital, Brisbane, between October 2009 and March 2010. Participants received full body and individual dermoscopic imaging of clinically significant naevi (≥2 mm on the back of male/female and lower limbs of female and ≥5 mm at other body sites). Dermoscopic patterns of naevi were compared between people at high versus moderate/low melanoma risk according to age and body site. Results: In both high and moderate/low risk groups, globular naevi predominated on the head/neck and abdomen/chest, reticular and non‐specific naevi on the back, and non‐specific pattern on the upper and lower limbs. Non‐specific naevi were the most common in all age groups. In both risk groups, globular naevi were more frequent in the younger age bracket, and reticular naevi were more frequent in the older age bracket. Mixed naevus patterns were infrequent and were more common in the younger age brackets of both risk groups. Conclusion: Our preliminary data shows that dermoscopic naevus patterns were similar for age and body site in people at different levels of melanoma risk, suggesting high melanoma risk does not influence dermoscopic naevus patterns.     

Pigmented spindle cell naevus of Reed: a controversial diagnostic entity in Australia

Background/Objectives: The Reed naevus or pigmented spindle cell naevus of Reed (PSCN) was previously considered a pigmented variant of the spindle cell‐type of Spitz naevus. It is now considered a distinct entity and may overlap with cutaneous melanoma in both clinical and dermatoscopic features. We hypothesised that PSCN is an under‐recognised entity in Australia and present a typical case. To test our hypothesis, we performed a clinically based survey of Australian dermatology trainees (Registrars). A further aim of our study was to determine the approach of dermatology trainees in this country to the management of this type of lesion. Methods: A web‐based survey questionnaire based on the presented case was circulated to trainees of the Australasian College of Dermatologists. Responses, including level of training and initial approach to management, were collated and form the basis of the results presented herein. Results: Of 39 respondents, 13 (33%) diagnosed the lesion as PSCN. The majority (33/39; 84.6%) indicated they would biopsy the lesion, with most of these (91%) preferring excisional biopsy. Conclusions: The results support our hypothesis that PSCN is under‐recognised in Australia. The results also show that despite difficulty distinguishing this lesion, management of these lesions by dermatology trainees in Australia is consistent and parallels current recommendations.     

Nevus on nevus. Apropos of 7 case reports, 3 of them associated with other dysplasias, and 1 with an invasive malignant melanoma

There is some doubt as to whether naevus pilus is identical with naevus-on-naevus or lentiginous naevus en mottes. The former could be classified together with Becker's naevus among the clinically progressive types of epidermal naevi, whereas the latter could be a truly melanocytic naevus of special expression which, for some authors, might become malignant. Seven cases of naevus-on-naevus with different sizes and locations are reported. In 3 cases the naevus was associated with other pathologies: pigmented sclerotic and kyphoscoliosis, verrucoid epidermal naevus, tuberous angioma and underlying muscular hypertrophy. In every case the diagnosis was confirmed by histological examination. An invasive malignant melanoma on superficial extensive melanoma coexisted with a retiform intradermal naevus pilosus. The hypothesis of complex neuro-ectodermic dysplasia and the histogenesis of malignant melanoma developed upon a naevus-on-naevus are discussed.     

HMB 45 positive balloon cells in combined nevi]

The combined naevus is made up of two components, one resembling a melanocytic naevus, the other a blue naevus. Clinically, these naevi do not give any obvious cause for concern. Histological examination shows that the combined naevus consists of a superficial melanocytic naevus and a deep-seated spindle cell blue naevus. There is a rare variant in which the pigmented spindle cells of the "blue" naevus are replaced by large balloon cells varying in melanin content. These combined naevi, because of the large cells with abundant cytoplasm, closely resemble malignant melanoma. As a further aid to diagnosis we used the monoclonal antibody HMB 45. In our study, the vesicular cells in all seven combined naevi examined reacted strongly with HMB 45. It is suggested that HMB 45 is not always helpful in differentiating between melanoma and naevi.     

Halo congenital naevus in a middle-aged patient with vitiligo

A case of halo congenital naevus is reported on the chest of a 56-year-old Asian woman with pre-existing vitiligo. The naevus measured 3.5 cm x 2 cm and underwent depigmentation around its periphery. Dermoscopic examination showed coarse pigment in the darker centre of the naevus and depigmentation in the surrounding halo. Light microscopy showed well-formed naevus cell nests with coarse melanin granules in the papillary dermis, and surrounding fibrosis. Melanocytes extended into reticular dermis, consistent with a congenital growth pattern. There was no evidence of malignancy. The epidermis was of normal appearance. S100 staining highlighted melanocytes in the dermis. Basal melanocytes were retained at the periphery of the naevus. Based on the clinical history and histological findings, a diagnosis of halo congenital naevus was made. The naevus was not excised.