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DOI: 10.1111/jdv.12291
REVIEW ARTICLE
Melanocytic nevi with special features: clinicaldermoscopic and reflectance confocal microscopicfindings A. Larre Borges,1 I. Zalaudek,2,3 C. Longo,3 L. Dufrechou,1 G. Argenziano,3,* A. Lallas,3 S. Piana,3 E. Moscarella3 Dermatology Unit, Hospital de Clınicas ‘Dr. Manuel Quintela’, Montevideo, Uruguay Department of Dermatology, Medical University of Graz, Graz, Austria 3 Skin Cancer Unit, Arcispedale S. Maria Nuova, IRCCS, Reggio Emilia, Italy *Correspondence: G. Argenziano. E-mail: [email protected] 1 2
Abstract Histopathology is considered the ‘gold’ standard for the diagnosis and classification of melanocytic nevi, but the widespread use of in vivo diagnostic technologies such as dermoscopy and reflectance confocal microscopy (RCM), has enriched profoundly the knowledge regarding the morphological variability in nevi. This is because most morphological observations made via these in vivo tools are closely correlated with features seen in histopathology. Dermoscopy has allowed for a more detailed classification of nevi. As such, dermoscopy identifies four main morphologic groups (i.e. globular, reticular, starburst and structureless blue nevi), one group of nevi located at special body sites (i.e. face, acral, nail) and one group of nevi with special features. This latter category consists of nevi of the former categories, which are typified by peculiar clinical-histopathological findings. They can be subdivided into ‘melanoma simulators’ including combined nevi, recurrent nevi and sclerosing nevus with pseudomelanomatous features, ‘targetoid’ nevi (i.e. halo, cockade, irritated targetoid haemosiderotic and eczematous nevus) and uncommon histopathological variants such as desmoplastic, white dysplastic or ballon cell nevus. While the dermoscopic and RCM patterns of the former categories have been studied in detail, little is currently known about the clinical morphology of the heterogeneous group of ‘special’ nevi. In this article, we describe the clinical, dermoscopic and RCM features of ‘special’ nevi and review the current literature on this group of melanocytic proliferations. Received: 22 May 2013; Accepted: 18 September 2013
Conflicts of interest None declared.
Funding sources Study supported in part by the Italian Ministry of Health RF-2010-2316524.
Introduction The classification of melanocytic nevi is an evolving science and different classification schemes have been established based on the method of obtaining morphological information. While clinical (non-dermoscopic) classification invokes flat, elevated and nodular subtypes, Ackerman and Magana-Garcia1 proposed a scheme based on the histological criteria of Clarks, Miescher, Unna and Spitz nevi. Dermoscopically, nevi are classified into four main groups (i.e. globular, reticular, starburst, structureless blue nevi) and two subgroups including nevi of special body sites (acral, nail, face) and nevi with special features.2,3 The latter category consists of nevi of the former categories, which exhibit
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peculiar clinical-histopathological features. Special nevi can be further subdivided into ‘melanoma simulators’ including combined nevi, recurrent nevi (RN) and sclerosing nevus with pseudomelanomatous features, ‘targetoid’ nevi (i.e. halo, cockade, irritated targetoid haemosiderotic and eczematous nevus) and uncommon histopathological variants such as desmoplastic, white dysplastic or balloon cell nevus (BCN). While the dermoscopic and reflectance confocal microscopy (RCM) patterns of the main categories of nevi have been studied in detail,2–7 little is currently known about the clinical morphology of the heterogeneous group of ‘special’ nevi. The aim of this article was to describe the clinical, dermoscopic and RCM features of a
© 2013 European Academy of Dermatology and Venereology
Larre Borges et al.
2
series of nevi with special features along with a review of the literature.
of a central structureless blue papule or plaque (blue nevus) surrounded by a brownish area.
Melanoma simulators
Dermoscopy Dermoscopic patterns of combined nevi have been
described only in a small series of 21 cases including 17 cases of blue nevus associated with a dermal and/or compound nevus, two cases of blue nevus with a Clark nevus, one SN combined with a Clark nevus and one SN associated with a congenital nevus.10–13 Because of the presence of two nevus cell populations, colour variegations or more than one structure, depending on the nevus types, are often present. The most classic type (blue nevus associated with compound or dermal nevus) is characterized by a delicate peripheral reticular pattern and/or globular pattern, respectively, and a central structureless blue pigmentation (Fig. 1). Combined nevi lacking a blue nevus component might reveal less specific features under dermoscopy.10,13
Combined nevi Clinical features Combined melanocytic nevi are defined as the histopathological presence of two different types of melanocytic proliferations within the same nevus.8 They represent approximately 1% of all excised nevi and are most commonly located on the back.9 Histopathological studies suggest that the most frequent combination is that of a blue nevus associated with either a Spitz nevus (SN), acquired melanocytic nevus or congenital melanocytic nevus.9 It remains unclear whether combined nevi represent the coexistence of two discrete nevus cell populations or whether they reflect divergent terminal differentiation of a single cell population.8,9 Depending on the dominant histopathological component, combined nevi may appear clinically as blue nevi, common nevi, Clark nevi, congenital or Spitz nevi. The most stereotypical appearance of a combined nevus is that
(a)
(c)
Reflectance confocal microscopy Reflectance confocal microscopy features of combined nevi have not been specifically described since now. However, because RCM allows the visualization of microscopic structures in vivo at a cellular level
(b)
(d)
Figure 1 Combined nevus. (a) Clinical image of a 1 cm in diameter nevus on the back of a patient with multiple nevi. The lesion is symmetric but shows colour variegation, from pink to light brown to blue colour. (b) Colour variegation is visible under dermoscopy. The lesion presents a bluish area centring a pink background, a small eccentric area of structureless brown pigmentation is visible at the periphery. Dotted vessels are regularly distributed throughout the lesions, multiple milia-like cysts are visible as shiny white round globules. (c) RCM. Mosaic image at the level of the superficial dermis, revealing a well-circumscribed lesion were multiple dense melanocytic nests are visible. At the deeper imaging section only the congenital component is well visualized, however, no melanoma features are visible. Multiple keratin cysts are visible as shiny-white concentric structures (white arrows) (d) Close up of a dense cell nevus nest located in the dermis.
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© 2013 European Academy of Dermatology and Venereology
Melanocytic nevi with special features
3
resolution, a combination of two nevus cell population can be detected. One limit in the confocal evaluation can be the case of a deep dermal or blue nevus not detectable because of the limits in depth penetration of RCM.14–16 Moreover, in case of a differential diagnosis with melanoma, RCM can reveal the presence or absence of specific melanoma features (Fig. 1).16 Management Combined nevi are important simulators of melanoma and vice versa. For this reason, excision of combined nevi is generally recommended.10 Recurrent nevi Clinical features Recurrent nevi are benign melanocytic nevi that regrow after incomplete surgical excision or trauma. Most RN originate from ‘ordinary’ or common acquired nevi removed for cosmetic reasons by means of a shave biopsy; less often, recurrences may arise from incomplete excision of congenital, Clark Spitz and blue nevi.17,18 They characteristically occur in women from 20 to 30 years of age, most often on the back, followed by face and extremities.17,18 Clinically, they present as a macular area of scar with variegated hyperpigmentation and hypopigmentation, linear streaking, and halo, stippled, and/or diffuse pigmentation.19,20 The recurrence usually appears in the centre of the scar approximately 6 weeks to 6 months after incomplete surgical removal of a nevus.17 The mechanism of recurrence in nevi remains to be further elucidated. However, different hypothesis have been proposed including seeding of melanocytes during the mechanical removal, junctional stimulation originating from remaining hair roots or the periphery of the lesion, growth stimulation signal mediated by residual nevus cells, repopulation by adnexal structures and regrowth from the residual dermal nevus.17,19,20 Dermoscopy Differential diagnosis of RN includes recurrent
melanoma and melanotic pigmentation (reactive pigmentation) within a scar. Time of occurrence of the pigmentation after the surgical procedure, distribution of the pigmentation within the scar and evaluation of dermoscopic structures are clue parameters aiding a correct classification of these lesions. Regarding the
(a)
time of occurrence, a quick recurrence of the pigmentation (up to 6 months after excision) favours a diagnosis of a benign recurrent nevus, whereas melanomas usually recur slowly, several months to years after excision. Benign recurrences are confined to the scar, arising in the centre of the scar and extending within the scar.21,22 Melanomas tend to recur beyond the bounds of the scar onto the normal skin.21–23 Melanotic pigmentation tend to extend perpendicular to the main axis of the scar, and seem to be leaned above it.23–25 Botella-Estrada et al.23 described clinical, dermoscopy and histological features of melanotic pigmentations in excision scars of melanocytic tumours. They analysed clinical and dermoscopic features of 95 melanotic pigmentation arising in a scar after surgical removal of melanocytic lesions. Regular pigmented network and thin continuous streaks were associated with reactive pigmentations, whereas irregular prominent network, globules and heterogeneous pigmentation were features associated with specific melanocytic pigmentations. In a recent study of the International Dermoscopy Society (IDS),26 authors evaluated the dermoscopic features of 160 cases of RN and recurrent melanomas. Symmetric and centrifugal growth pattern were significantly more common in RN; in contrast circles, eccentric hyperpigmentation at the periphery, chaotic and non-continuous growth pattern and pigmentation beyond the scar’s edge were significantly more common in recurrent melanomas.26 From a dermatoscopic point of view, pigmentation beyond the scar’s edge was the strongest clue for melanoma; however, the final interpretation should consider patient’s age, anatomic site, time to recurrence, growth pattern and, if available, histopathology of the first excision (Fig. 2).26 Reflectance confocal microscopy Reflectance confocal microscopy features of RN and their differential diagnosis with melanoma have been recently described.22 RCM has a particular value in the case of unknown histological diagnosis of the primary tumour. Longo et al.22 described clinical, dermoscopic and RCM features of seven histopathologically diagnosed cases of recurrent melanocytic proliferations. RN did not exhibit prominent pagetoid or lateral spread of melanocytes and atypical nests at the junction, although some cases showed atypical cells in the
(b)
Figure 2 Recurrent nevus. (a) Clinical picture of a pigmented lesion on the back, recurring after shave biopsy. (b) Dermoscopy, displaying the presence of a melanocytic proliferation confined into the margins of the scar, characterized by a brown to black pigment network with a radial distribution, starting from the centre of the scar and going towards the periphery.
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© 2013 European Academy of Dermatology and Venereology
Larre Borges et al.
4
junctional component. However, these were few in number and cytologically monomorphous and allowed the diagnosis of a benign neoplasm with confidence (Fig. 3).22
area, probably due to the chronic trauma(s) that frequently occur in this body area or else, to the effect of some concurrent ‘deep’ inflammatory dermatosis (e.g.: acne).
Management Recurrent nevi are also referred to as ‘pseudomelanomas’, because they are melanoma simulators both dermoscopically and histopathologically. In cases with a previous histopathological confirmation of a nevus, no further treatment is warranted. In cases however, in which no previous histopathological diagnosis is available or in which clinical and dermoscopic features are controversial, complete excision is mandatory. As RN may mimic also histopathologically melanoma, it is of uppermost importance to provide the pathologists with the clinical information of a previous surgical procedure.
Dermoscopy Nevi with regression-like fibrosis are pigmented
Sclerosing nevi with pseudomelanomatous features Clinical features Sclerosing nevus with pseudomelanomatous features is a recently described entity which can clinically and a histopathologically simulate regressing melanoma.27–29 They are also called ‘nevi with regression-like fibrosis’ (NRLF). The aetiology of this type of nevus is attributed to a minor or unnoticed trauma(s) on a pre-existing nevus. Histopathologically NRLF exhibit a trizonal pattern: (i) an atypical junctional proliferation associated with some pagetoid spreading; (ii) significant area(s) of dermal sclerosis containing architecturally atypical melanocytic nests; (iii) residual nevus tissue (often with congenital-like features) around and deep into the cicatricial tissue. According to Fabrizi et al.28 NRLF can be differentiated from regressing melanoma by lacking cytologic atypia, dermal mitoses, cell necrosis, tumoural melanosis and expansile dermal nodule(s) of atypical melanocytes.27–29 It appears in young to middle-aged men, mostly located on convex area of the back, i.e. the scapular
(a)
Reflectance confocal microscopy Nevi with regression-like fibrosis have not been described in the literature up to now. In the present case, RCM showed the presence of a ill-defined lesion, with junctional thickening and numerous melanophages at the dermoepidermal junction (DEJ). In RCM, the presence of cellular atypia and focal pagetoid spread did not allow an accurate differential diagnosis with regressive melanoma, reflecting the difficulties often encountered also in histopathology (Fig. 5). Management As NRLF is a melanoma simulator these lesions are usually routinely excised to rule out melanoma.
Targetoid nevi Cockade nevi Clinical features This nevus is characterized by a central pink to darkly pigmented, often papular portion, which is surrounded
(b)
(c)
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atypical lesion showing overall features of regression, which is invariably extensive (between 10% and 50%) and polychromatic (coexisting white and blue areas), in absence of melanoma specific criteria. There are some criteria that rise the index of suspicion of NRLF: young/middle-aged patients; lesions located in the convex area of the back; symmetric-central distribution of regression; blue or polychromatic regression; limited regression (
DOI: 10.1111/jdv.12291
REVIEW ARTICLE
Melanocytic nevi with special features: clinicaldermoscopic and reflectance confocal microscopicfindings A. Larre Borges,1 I. Zalaudek,2,3 C. Longo,3 L. Dufrechou,1 G. Argenziano,3,* A. Lallas,3 S. Piana,3 E. Moscarella3 Dermatology Unit, Hospital de Clınicas ‘Dr. Manuel Quintela’, Montevideo, Uruguay Department of Dermatology, Medical University of Graz, Graz, Austria 3 Skin Cancer Unit, Arcispedale S. Maria Nuova, IRCCS, Reggio Emilia, Italy *Correspondence: G. Argenziano. E-mail: [email protected] 1 2
Abstract Histopathology is considered the ‘gold’ standard for the diagnosis and classification of melanocytic nevi, but the widespread use of in vivo diagnostic technologies such as dermoscopy and reflectance confocal microscopy (RCM), has enriched profoundly the knowledge regarding the morphological variability in nevi. This is because most morphological observations made via these in vivo tools are closely correlated with features seen in histopathology. Dermoscopy has allowed for a more detailed classification of nevi. As such, dermoscopy identifies four main morphologic groups (i.e. globular, reticular, starburst and structureless blue nevi), one group of nevi located at special body sites (i.e. face, acral, nail) and one group of nevi with special features. This latter category consists of nevi of the former categories, which are typified by peculiar clinical-histopathological findings. They can be subdivided into ‘melanoma simulators’ including combined nevi, recurrent nevi and sclerosing nevus with pseudomelanomatous features, ‘targetoid’ nevi (i.e. halo, cockade, irritated targetoid haemosiderotic and eczematous nevus) and uncommon histopathological variants such as desmoplastic, white dysplastic or ballon cell nevus. While the dermoscopic and RCM patterns of the former categories have been studied in detail, little is currently known about the clinical morphology of the heterogeneous group of ‘special’ nevi. In this article, we describe the clinical, dermoscopic and RCM features of ‘special’ nevi and review the current literature on this group of melanocytic proliferations. Received: 22 May 2013; Accepted: 18 September 2013
Conflicts of interest None declared.
Funding sources Study supported in part by the Italian Ministry of Health RF-2010-2316524.
Introduction The classification of melanocytic nevi is an evolving science and different classification schemes have been established based on the method of obtaining morphological information. While clinical (non-dermoscopic) classification invokes flat, elevated and nodular subtypes, Ackerman and Magana-Garcia1 proposed a scheme based on the histological criteria of Clarks, Miescher, Unna and Spitz nevi. Dermoscopically, nevi are classified into four main groups (i.e. globular, reticular, starburst, structureless blue nevi) and two subgroups including nevi of special body sites (acral, nail, face) and nevi with special features.2,3 The latter category consists of nevi of the former categories, which exhibit
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peculiar clinical-histopathological features. Special nevi can be further subdivided into ‘melanoma simulators’ including combined nevi, recurrent nevi (RN) and sclerosing nevus with pseudomelanomatous features, ‘targetoid’ nevi (i.e. halo, cockade, irritated targetoid haemosiderotic and eczematous nevus) and uncommon histopathological variants such as desmoplastic, white dysplastic or balloon cell nevus (BCN). While the dermoscopic and reflectance confocal microscopy (RCM) patterns of the main categories of nevi have been studied in detail,2–7 little is currently known about the clinical morphology of the heterogeneous group of ‘special’ nevi. The aim of this article was to describe the clinical, dermoscopic and RCM features of a
© 2013 European Academy of Dermatology and Venereology
Larre Borges et al.
2
series of nevi with special features along with a review of the literature.
of a central structureless blue papule or plaque (blue nevus) surrounded by a brownish area.
Melanoma simulators
Dermoscopy Dermoscopic patterns of combined nevi have been
described only in a small series of 21 cases including 17 cases of blue nevus associated with a dermal and/or compound nevus, two cases of blue nevus with a Clark nevus, one SN combined with a Clark nevus and one SN associated with a congenital nevus.10–13 Because of the presence of two nevus cell populations, colour variegations or more than one structure, depending on the nevus types, are often present. The most classic type (blue nevus associated with compound or dermal nevus) is characterized by a delicate peripheral reticular pattern and/or globular pattern, respectively, and a central structureless blue pigmentation (Fig. 1). Combined nevi lacking a blue nevus component might reveal less specific features under dermoscopy.10,13
Combined nevi Clinical features Combined melanocytic nevi are defined as the histopathological presence of two different types of melanocytic proliferations within the same nevus.8 They represent approximately 1% of all excised nevi and are most commonly located on the back.9 Histopathological studies suggest that the most frequent combination is that of a blue nevus associated with either a Spitz nevus (SN), acquired melanocytic nevus or congenital melanocytic nevus.9 It remains unclear whether combined nevi represent the coexistence of two discrete nevus cell populations or whether they reflect divergent terminal differentiation of a single cell population.8,9 Depending on the dominant histopathological component, combined nevi may appear clinically as blue nevi, common nevi, Clark nevi, congenital or Spitz nevi. The most stereotypical appearance of a combined nevus is that
(a)
(c)
Reflectance confocal microscopy Reflectance confocal microscopy features of combined nevi have not been specifically described since now. However, because RCM allows the visualization of microscopic structures in vivo at a cellular level
(b)
(d)
Figure 1 Combined nevus. (a) Clinical image of a 1 cm in diameter nevus on the back of a patient with multiple nevi. The lesion is symmetric but shows colour variegation, from pink to light brown to blue colour. (b) Colour variegation is visible under dermoscopy. The lesion presents a bluish area centring a pink background, a small eccentric area of structureless brown pigmentation is visible at the periphery. Dotted vessels are regularly distributed throughout the lesions, multiple milia-like cysts are visible as shiny white round globules. (c) RCM. Mosaic image at the level of the superficial dermis, revealing a well-circumscribed lesion were multiple dense melanocytic nests are visible. At the deeper imaging section only the congenital component is well visualized, however, no melanoma features are visible. Multiple keratin cysts are visible as shiny-white concentric structures (white arrows) (d) Close up of a dense cell nevus nest located in the dermis.
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© 2013 European Academy of Dermatology and Venereology
Melanocytic nevi with special features
3
resolution, a combination of two nevus cell population can be detected. One limit in the confocal evaluation can be the case of a deep dermal or blue nevus not detectable because of the limits in depth penetration of RCM.14–16 Moreover, in case of a differential diagnosis with melanoma, RCM can reveal the presence or absence of specific melanoma features (Fig. 1).16 Management Combined nevi are important simulators of melanoma and vice versa. For this reason, excision of combined nevi is generally recommended.10 Recurrent nevi Clinical features Recurrent nevi are benign melanocytic nevi that regrow after incomplete surgical excision or trauma. Most RN originate from ‘ordinary’ or common acquired nevi removed for cosmetic reasons by means of a shave biopsy; less often, recurrences may arise from incomplete excision of congenital, Clark Spitz and blue nevi.17,18 They characteristically occur in women from 20 to 30 years of age, most often on the back, followed by face and extremities.17,18 Clinically, they present as a macular area of scar with variegated hyperpigmentation and hypopigmentation, linear streaking, and halo, stippled, and/or diffuse pigmentation.19,20 The recurrence usually appears in the centre of the scar approximately 6 weeks to 6 months after incomplete surgical removal of a nevus.17 The mechanism of recurrence in nevi remains to be further elucidated. However, different hypothesis have been proposed including seeding of melanocytes during the mechanical removal, junctional stimulation originating from remaining hair roots or the periphery of the lesion, growth stimulation signal mediated by residual nevus cells, repopulation by adnexal structures and regrowth from the residual dermal nevus.17,19,20 Dermoscopy Differential diagnosis of RN includes recurrent
melanoma and melanotic pigmentation (reactive pigmentation) within a scar. Time of occurrence of the pigmentation after the surgical procedure, distribution of the pigmentation within the scar and evaluation of dermoscopic structures are clue parameters aiding a correct classification of these lesions. Regarding the
(a)
time of occurrence, a quick recurrence of the pigmentation (up to 6 months after excision) favours a diagnosis of a benign recurrent nevus, whereas melanomas usually recur slowly, several months to years after excision. Benign recurrences are confined to the scar, arising in the centre of the scar and extending within the scar.21,22 Melanomas tend to recur beyond the bounds of the scar onto the normal skin.21–23 Melanotic pigmentation tend to extend perpendicular to the main axis of the scar, and seem to be leaned above it.23–25 Botella-Estrada et al.23 described clinical, dermoscopy and histological features of melanotic pigmentations in excision scars of melanocytic tumours. They analysed clinical and dermoscopic features of 95 melanotic pigmentation arising in a scar after surgical removal of melanocytic lesions. Regular pigmented network and thin continuous streaks were associated with reactive pigmentations, whereas irregular prominent network, globules and heterogeneous pigmentation were features associated with specific melanocytic pigmentations. In a recent study of the International Dermoscopy Society (IDS),26 authors evaluated the dermoscopic features of 160 cases of RN and recurrent melanomas. Symmetric and centrifugal growth pattern were significantly more common in RN; in contrast circles, eccentric hyperpigmentation at the periphery, chaotic and non-continuous growth pattern and pigmentation beyond the scar’s edge were significantly more common in recurrent melanomas.26 From a dermatoscopic point of view, pigmentation beyond the scar’s edge was the strongest clue for melanoma; however, the final interpretation should consider patient’s age, anatomic site, time to recurrence, growth pattern and, if available, histopathology of the first excision (Fig. 2).26 Reflectance confocal microscopy Reflectance confocal microscopy features of RN and their differential diagnosis with melanoma have been recently described.22 RCM has a particular value in the case of unknown histological diagnosis of the primary tumour. Longo et al.22 described clinical, dermoscopic and RCM features of seven histopathologically diagnosed cases of recurrent melanocytic proliferations. RN did not exhibit prominent pagetoid or lateral spread of melanocytes and atypical nests at the junction, although some cases showed atypical cells in the
(b)
Figure 2 Recurrent nevus. (a) Clinical picture of a pigmented lesion on the back, recurring after shave biopsy. (b) Dermoscopy, displaying the presence of a melanocytic proliferation confined into the margins of the scar, characterized by a brown to black pigment network with a radial distribution, starting from the centre of the scar and going towards the periphery.
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© 2013 European Academy of Dermatology and Venereology
Larre Borges et al.
4
junctional component. However, these were few in number and cytologically monomorphous and allowed the diagnosis of a benign neoplasm with confidence (Fig. 3).22
area, probably due to the chronic trauma(s) that frequently occur in this body area or else, to the effect of some concurrent ‘deep’ inflammatory dermatosis (e.g.: acne).
Management Recurrent nevi are also referred to as ‘pseudomelanomas’, because they are melanoma simulators both dermoscopically and histopathologically. In cases with a previous histopathological confirmation of a nevus, no further treatment is warranted. In cases however, in which no previous histopathological diagnosis is available or in which clinical and dermoscopic features are controversial, complete excision is mandatory. As RN may mimic also histopathologically melanoma, it is of uppermost importance to provide the pathologists with the clinical information of a previous surgical procedure.
Dermoscopy Nevi with regression-like fibrosis are pigmented
Sclerosing nevi with pseudomelanomatous features Clinical features Sclerosing nevus with pseudomelanomatous features is a recently described entity which can clinically and a histopathologically simulate regressing melanoma.27–29 They are also called ‘nevi with regression-like fibrosis’ (NRLF). The aetiology of this type of nevus is attributed to a minor or unnoticed trauma(s) on a pre-existing nevus. Histopathologically NRLF exhibit a trizonal pattern: (i) an atypical junctional proliferation associated with some pagetoid spreading; (ii) significant area(s) of dermal sclerosis containing architecturally atypical melanocytic nests; (iii) residual nevus tissue (often with congenital-like features) around and deep into the cicatricial tissue. According to Fabrizi et al.28 NRLF can be differentiated from regressing melanoma by lacking cytologic atypia, dermal mitoses, cell necrosis, tumoural melanosis and expansile dermal nodule(s) of atypical melanocytes.27–29 It appears in young to middle-aged men, mostly located on convex area of the back, i.e. the scapular
(a)
Reflectance confocal microscopy Nevi with regression-like fibrosis have not been described in the literature up to now. In the present case, RCM showed the presence of a ill-defined lesion, with junctional thickening and numerous melanophages at the dermoepidermal junction (DEJ). In RCM, the presence of cellular atypia and focal pagetoid spread did not allow an accurate differential diagnosis with regressive melanoma, reflecting the difficulties often encountered also in histopathology (Fig. 5). Management As NRLF is a melanoma simulator these lesions are usually routinely excised to rule out melanoma.
Targetoid nevi Cockade nevi Clinical features This nevus is characterized by a central pink to darkly pigmented, often papular portion, which is surrounded
(b)
(c)
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atypical lesion showing overall features of regression, which is invariably extensive (between 10% and 50%) and polychromatic (coexisting white and blue areas), in absence of melanoma specific criteria. There are some criteria that rise the index of suspicion of NRLF: young/middle-aged patients; lesions located in the convex area of the back; symmetric-central distribution of regression; blue or polychromatic regression; limited regression (
