Spitz / Reed nevi
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Evolution of Spitz nevi
Management of Spitz nevi
In 1948, Sophie Spitz described a group of melanocyticThis glossary term has not yet been described. lesions of children, first considered as “melanomas of childhood, and subsequently histologically categorized as benignis any condition that is harmless in the long run melanocytic proliferations, then renamed as “Spitz neviThis glossary term has not yet been described.”.
The majority of Spitz neviThis glossary term has not yet been described. occur in patients younger than 20 years and are less common in adulthood and elderly . Clinically, the Spitz nevusThis glossary term has not yet been described. (SN) appears as a solitary, asymptomatic, round to oval, dome-shaped, papule or nodule usually located on the head, neck or extremities of young individuals. In its classic clinical appearance it is pink or red in colour due to a low melanin production and has a rapid growth; however, brown and even black pigmented SN do exist and are especially seen in young adults. In 1975, Reed et al. described a benign pigmented melanocytic lesion commonly founds on the lower extremities of young female, that after was titled as “Reed nevusThis glossary term has not yet been described.”. This kind of lesion, histopathologically presents a heavy pigmentation due to oval-spindle melanocytes arranged in nest and fascicles, whereas clinically appears as a solitary, dark brown to black, dome-shape papule or jet-black plaque.
Since 1978, the nosological autonomy of Reed nevus from Spitz nevus has been inquired. Some authors include Reed nevus to the morphological spectrum of Sptiz nevusThis glossary term has not yet been described., while other authors still classify Reed nevus as an independent entity differentiated from pigmented Spitz nevus. The histopathologic distinction between Spitz nevus and Reed nevus is often matter of great debate. Nowadays, we distinguish two clinical variants of SN, the classical and the pigmented types, the latter include Reed nevus.
The most important issue of SN is their propensity to mimic melanomaThis glossary term has not yet been described. clinically, dermatoscopically and histopathologicallly. Moreover, some melanomas histopathologically may resemble Spitz nevi for their “Spitzoid” features and for this reason have been called “Spitzoid melanomas.”
Spitzoid lesions represent a difficultneeding much effort or skill to accomplish and controversial group of tumours, in terms of clinical identification, biologic behaviour and managementThis glossary term has not yet been described. strategies. Spitz and Reed nevi are benign tumours, but on the other side of the spectrum of spitzoid lesions, there are “Spitzoid melanomas” undoubtedly malignantThis glossary term has not yet been described.. Between these two extremes, a series of spitzoid lesions, defined as “ atypical Spitz tumors” and “ melanocytic tumors of uncertain malignant potential (MELTUMP)”, do exist. This is the major reason why evidence-based management guidelines for these kinds of tumours are difficult to define.
The use of dermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections. has increased the accuracy in the diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions of SN allowing a better understanding of their evolving behavior. Spitz/Reed nevi can be classified according six different dermoscopic appearances, namely, vascular (pink homogenous), globular, starburst, reticular, atypical and homogenous patternstructureless any color. In their growing phases, Spitz nevi evolve from globular patternThis glossary term has not yet been described. to a starburst patternThis pattern consists of peripheral globules, pseudopods or streaks (or a combination of them), located around the entire perimeter of the lesion with regular streaksThis glossary term has not yet been described. at the periphery (finger like or globuleThis glossary term has not yet been described. like). After several months, the peripheral projections disappear and the lesion becomes stable with a dermoscopic homogeneous, structureless brown-to-black pigmentation. Finally, in the last phases the lesion involves and loses its pigmentation. Simplifying, SN can show, demoscopically, three main patternsThis glossary term has not yet been described.: a starburst pattern, a vascular pattern with regularly distributed dotted vesselstiny pinpoint vessels and a globular pattern with reticular depigmentation.
Non pigmented Spitz nevus
The dermoscopic hallmark of non pigmented Spitz nevus is the vascular pattern, detectable as dotted vessels (Figure 1), monomorphic and uniformly distributed throughout the lesion. In raised or nodular Spitz nevi, the vesselsThis glossary term has not yet been described. might not appear as small dotsDots are small, round structures of less than 0.1 mm in diameter that have a red color when corresponding to blood vessels; however, when due to melanin, their color ranges from black, brown, to blue-gray depending on the depth and concentration of the melanin in the skin (Tyndall effect)., but as larger red globulesThis glossary term has not yet been described., twisted (spiral), hairpin or corkscrew vesselstwisted looped vessels with bends twisted along a central axis melanoma metastasis, nevertheless their distribution is symmetric. When vascular structuresThis glossary term has not yet been described. are asymmetrically distributed, or there is brownish color and tan/brown globules within lesion, the lesion is more suggestive for melanoma8. Another frequent additional feature of non pigmented SN is reticular depigmentation (Figure 2) visible either as a negative networkSerpiginous interconnecting broadened hypopigmented lines that surround elongated and curvilinear globules. (a whitish grid surrounding the vessels), or as chrysalis-like structuresThis glossary term has not yet been described. (shiny white lines that are often oriented orthogonally or in parallel to each other). Moreover, while negative network can be visualized with both polarized and no polarized dermoscopy, crystalline structures can be seen only with polarized lightThis glossary term has not yet been described.. The differential diagnosis of non pigmented SN includes a series of no melanocytic lesions such as pyogenic granulomaThis glossary term has not yet been described., hemangiomaThis glossary term has not yet been described., solitary mastocitoma, juvenile xantogranuloma, lymphoid infiltration of the skinThis glossary term has not yet been described., angiolymphoid hyperplasia with eosinophilia, dermatofibromaDermatofibromas are hard solitary slow-growing papules (rounded bumps) that may appear in a variety of colours, usually brownish to tan; they are often elevated or pedunculated. A dermatofibroma is associated with the dimple sign; by applying lateral pressure, there is a central depression of the dermatofibroma. and viral wart.
At histologyThis glossary term has not yet been described., they show a melanocytic proliferation, polygonal or cigar-shaped, with large nuclei, prominent nucleoli, and abundant ground-glass cytoplasm. Large and coalescent eosinophilic bodies (Kamino) at dermoThis glossary term has not yet been described.-epidermal junction, edema, teleangectasias and fibrosis of the papillary dermis and melanin within spindle cells and dermal melanophages are also frequently seen.
Pigmented Spitz nevus
Pigmented SN could show a globular, starburst, reticular, atypical or homogeneous patternA pattern lacking any definable pigment structures, structureless pattern dermoscopically . The globular pattern, presents in about 20% of SN, consists of gray-brown to blue globulesclods blue small generally distributed throughout the lesion or mostly at the periphery. A starburst aspect is possible if the peripheral globulesThis glossary term has not yet been described. are merging with the central body of the lesion. The globular pattern of Spitz nevi differs from the globular pattern seen in growing Clark nevi, because the peripheral globules are distributed in a single row for the latter, while in multiple rows for SN (Fig. 3).
The starburst pattern, indicating the radial growth phase of the tumor, consists of a central homogenous black-blue pigmentation surrounded by streakslines radial (always at periphery) streaks Reed nevus melanoma recurrent nevus, pseudopods or finger-like projection regularly and symmetrically distributed at periphery (Fig. 4).
Heavily pigmented Spitz nevi are predominant in children under 12 years of ageprocess of becoming older. They often exhibit a reticular pattern well visible at the periphery and a central black lamella due to excessive amounts of melanin in the stratum corneum (Fig. 5). The tape strippingThis glossary term has not yet been described. removes the black lamella, but not the pigmented networkThis glossary term has not yet been described..
SN with atypical multicomponent dermoscopic pattern have a “melanoma like” appearance and are characterized, by atypical pigment networkNetwork with increased variability in the color, thickness, and spacing of the lines of the network; asymmetrically distributed; gray color, irregular dotsAny distribution of dots other than dots as described for regular dots. and globules, irregular pigmentation and irregular streaksThis glossary term has not yet been described. (Fig. 6). These features can be also simultaneously present and associated with blue-whitish veil. These SN are very difficult to differentiate clinically, dermoscopically and histopathologically from melanoma.
Black Spitz nevi could show at dermoscopy also a homogenous pattern with only a dark brown to black–bluish color without any other dermoscopic structure (Fig.7). The homogenous and reticular patterns have been suggested to represent the later evolutionis change in the heritable characteristics of biological populations over successive generations phases of the starburst pattern; in fact, they are more frequent among older patients.
At histology, pigmented SN present as heavily pigmented lesions, with cohesive spindle and/or epithelioid melanocytes, parallel and perpendicular to the skin surface.
Figure 7: This structureless lesion show a homogenous pattern characterized by a dark brown to black-bluish colorColor (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or blue..
Natural evolution of Spitz nevi
The starburst, globular and atypical patterns are the most common morphologic variants of SN and correspond to the different phases of the natural evolution of Spitz nevi. At beginning, pigmented Spitz nevi show a globular pattern and, after a variable number of months, a starburst pattern. Differently from melanoma, in SN the peripheral projections disappear over time and the lesion becomes stable thus showing a homogeneous pattern. The progressive decrease of pigmentation or the complete involutionThis glossary term has not yet been described. of the lesion are the last evolution stages for a pigmented SN. The same behavior is also seen in amelanotic or hypopigmented SN; indeed, after a growing phase of several months they start to involve until final disappearance (Fig. 8).
Diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions and ManagementThis glossary term has not yet been described.
The diagnosis and management of patients with Spitz nevi could be difficult, above all because most cases of atypical Spitz nevi cannot be differentiated from melanoma. Some authors have proposed a conservative management in children based on the evidence that SN are very common at this age whereas melanoma is very rare. In children under 12 years of age with a classic or pigmented small (up to 1 cm) SN without asymmetry or atypical features, it is advisable to monitor the lesion every 6 months. If the lesion does not show irregular changes in shape, size and color over the time, a 1 year follow up can continue until the lesion stabilization or involution.
When Spitz nevi appear in children older than 12 years and in adult, surgical excision is always recommended because it is really hard to make a difference with spitzoid melanoma.
ReferencesThis is material contained in a footnote or bibliography holding further information.
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