Chapter III.11 Irritated Nevus and Meyerson’s Nevus III.11 Regina Fink-Puches, Iris Zalaudek, Rainer Hofmann-Wellenhof Contents III.11.2 Clinical Features III.11.1 Definition . .129 The occurrence of traumatic changes is frequent III.11.2 Clinical Features . .129 in melanocytic nevi, particularly in those that III.11.3 Dermoscopic Criteria. 130 are exophytic. Mechanical irritation by clothing and shaving is probably most often responsible, III.11.4 Relevant Clinical Differential but other forms of injury, such as scratching and Diagnosis. 130 accident, may occur. Traumatized nevi are often III.11.5 Histopathology. 131 found in the beard area of males and axillae of females [3]. Individuals often report a sudden III.11.6 Management. 131 change of pigmentation in the nevus, especially III.11.7 Case Study. .132 when they did not recognize the injury. Tender- References. .133 ness and itching are common symptoms. In traumatized nevus, a serocrust interspersed with hemorrhage mimicking irregular distribu- tion of pigmentation is present [4]. The sur- rounding skin usually is erythematous. A variant of traumatized nevus, namely, the targetoid hemosiderotic nevus has recently been described. The main presentation is the sudden development of an asymptomatic halo on a long- lasting, acquired nevus. The nevus is always III.11.1 Definition slightly exophytic or papillomatous. The nevus is surrounded by an ecchymotic, violaceous Benign melanocytic nevi exhibit a wide spec- halo causing a target-like phenomenon around trum of clinical, dermoscopic, and histopatho- the central nevus [1]. logical appearances. Most of them are histo- The UV-irradiated nevus may exhibit in- pathologically banal. There is, however, a creased pigmentation. The adjacent skin may percentage which show one or more unusual show an erythema according to the skin type [5, clinical features and require more attention. In- 6]. cluded among these are: (a) the irritated mela- Meyerson’s nevus is characterized by the de- nocytic nevus including the mechanically trau- velopment of an eczematous halo around one matized nevus with one special recently ore more pigmented nevi [2, 7]. Clinical features described variant, namely, the targetoid hemo- are the appearance of an erythematous halo siderotic nevus [1]; and (b) the UV-irradiated with overlying scales sometimes accentuated at nevus. A special variant is (c) Meyerson’s nevus, the periphery of the erythematous zone [8]. This which is surrounded by a halo of eczema in the process can be confined to one or all nevi of an same way that a halo of depigmentation sur- individual and may be accompanied by similar rounds a Sutton nevus [2]. lesions not associated with nevi [9]. Slight pruri- 130 R. Fink-Puches, I. Zalaudek et al. tus is a clinical symptom in most lesions. The In Meyerson’s nevi all dermoscopic criteria eczematous lesions become desquamative and of benign compound or junctional melanocytic clear spontaneously or resolve under topical nevi may be observed. therapy with corticosteroids. The nevi persist unchanged once the surrounding lesions have resolved. III.11.4 Relevant Clinical Differential Diagnosis III.11.3 Dermoscopic Criteria The clinical diagnosis of mechanically irritated nevus might be difficult. An irritated or trau- In irritated nevus dermoscopy is helpful to dif- matized nevus is a major simulator of melano- ferentiate blood and melanin pigmentation. ma, because exogenous irritation often results Targetoid hemosiderotic nevi show the typical in changes of colors due to the effects of inflam- features of acquired, compound melanocytic mation [14]. nevi with vascular–hemorrhagic changes super- Targetoid hemosiderotic nevus should be dif- imposed on the nevus and particularly sur- ferentiated from other pigmented lesions clini- rounding it: especially irregularly sized and cally with a peripheral halo, namely, a halo ne- shaped, jet-black areas and comma-shaped ves- vus, a Meyerson’s nevus, a cockade nevus, a sels are notified. The targetoid halo demon- targetoid hemosiderotic hemangioma and, most strates a pale, ill-defined inner area surrounded importantly, a melanoma. by a homogeneous reddish zone with peripheral A cockade nevus is a very rare variant of a jagged margins; however, there are no dermo- melanocytic nevus characterized by a peripher- scopic features specific for a hemangioma [1]. al pigmented halo with an intervening non-pig- Long-term as well as short-term UV irradia- mented zone [15]. tion may induce several changes in the dermo- Targetoid hemosiderotic hemangioma is a scopic features of melanocytic nevi. Stanganelli benign vascular lesion clinically presenting as a et al. found an increase in pigmentation and an single, small, annular target-like lesion on the increased prevalence of black dots in dermo- trunk or extremity of young adults [16, 17]. The scopic images of melanocytic nevi taken during lesion is composed of a brown to violaceous cen- the summer months [10]. Furthermore, a higher tral papule surrounded by a thin, pale area and frequency of broad and prominent pigment a peripheral ecchymotic ring, which expands network structures was observed. The same and subsequently disappears, whereas the cen- authors demonstrated that after 5–13 days of tral papule persists. Targetoid hemosiderotic intense natural sun exposure, nevi showed nevus may clinically simulate melanoma; thus, more black dots, brown globules, and pigment awareness of it is important to avoid unneces- network structures [11]. Hofmann-Wellenhof sary management procedures. et al. demonstrated that UV-irradiated nevi Ultraviolet irradiation induces transient exhibit significantly darker pigmentation and changes in melanocytic nevi that can be detect- brown-black globules show an increase in ed dermoscopically, leading in some cases to number and intensity, whereas hypopigmented diagnosis of melanoma; thus, the diagnosis of areas decrease. Moreover, the pigment network melanocytic skin lesions in patients after sun III.11 becomes more faded and less prominent [5]. exposure should be handled with care [5]. Espe- These changes were already observed 3 days af- cially the increase in black-brown globules and ter UV-irradiation with two minimal erythema darkening of pigmentation are often interpreted doses (MED) [12]. Remarkably, Tronnier and as signs of malignancy. [18–20]. In contrast, few colleagues demonstrated that a single erythe- hypopigmented areas, a faded border, and regu- matogenic UV-irradiation dose induces more larity of the pigment network are considered to effective melanoma-simulating changes than be dermoscopic criteria of benign lesions [19, fractionally applied UV doses [13]. 21]. Irritated Nevus and Meyerson’s Nevus Chapter III.11 131 III.11.5 Histopathology After exposure to UV irradiation, melano- cytic nevi may show intraepidermal features Histopathological examination of irritated me- simulating melanoma in situ with solitary me- lanocytic nevi reveals findings that depend, in lanocytes disposed not only at the dermo-epi- part, on the interval between irritation and ex- dermal junction but also in the upper epidermal cision. Acute changes, such as erosion or super- layers. The dermal component does not reveal ficial ulceration, marked spongiosis, and scale any hint for malignancy and, in addition, in- crust, are well-known features of an irritated traepidermal melanocytes do not show atypical nevus [22]. The phenomenon of an increase in features [24]. The described histopathological the number of suprabasal melanocytes after ir- features return to normality within a few weeks ritation of a nevus has been investigated by following UV irradiation. Tronnier et al. [14]. These melanocytes above Melanocytic nevi with eczematous halones the dermo-epidermal junction, particularly in (Meyerson’s nevi) may be either junctional or zones beneath foci of parakeratosis or scale compound nevi. The pathognomonic histo- crusts, are mostly arranged in solitary units, but pathological findings are focal parakeratosis, sometimes also in nests. These melanocytic punctuate crusts, variable amounts of spongio- nevi, which exhibit an increased number of su- sis with focal microvesiculation, epidermal hy- prabasal melanocytes, may be easily confused perplasia often of the psoriasiform type, and a histopathologically with melanoma [23]; how- moderately dense inflammatory infiltrate in the ever, the observation of suprabasal melanocytes papillary dermis [8]. This infiltrate is mostly should not be equated with the diagnosis of perivascular and composed of lymphocytes, melanoma. histiocytes, and a few eosinophils; however, Excoriated, abraded, or otherwise tormented there is no evidence of regression in a typical nevi frequently display features similar to those Meyerson’s nevus. of a persistent nevus (recurrent nevus or pseu- domelanoma) with a scar replacing the upper part of the dermis [22]. The scar is usually III.11.6 Management smaller and less prominent than in a conven- tional recurrent nevus. The “scar” or the fibro- Irritated nevi, including targetoid hemosiderot- plasia distorts the architecture of the nevus and ic nevi, return to normal clinical appearance is associated with occasional enlargement of 7–14 days after the initial trauma. A local anti- melanocytes; therefore, an irritated or trauma- inflammatory therapy or therapy with local tized nevus is an important histopathological heparinoid is recommended. A major pitfall is simulator of a regressive or of a “nevoid” mela- that melanomas may also show