Evolution of Spitz nevi
|Description||In this chapter we describe the natual evolutionis change in the heritable characteristics of biological populations over successive generations of Spitz neviThis glossary term has not yet been described. from globular to starburst to homogenous patternstructureless any color and their involutionThis glossary term has not yet been described..|
|Author(s)||Michael Kunz · Ralph P. Braun|
|Responsible author||Ralph Braun → send e-mail|
|Status update||June 12, 2017|
|Status by||Ralph P. Braun|
The natural evolution of melanocyticThis glossary term has not yet been described. neviThis glossary term has not yet been described. is a complex, multifactorial process involving constitutional and environmental factors. Among the various types of melanocytic nevi, Spitz nevi are the most controversial due to their morphologic vicinity to melanomaThis glossary term has not yet been described.. Spitz nevi usually present as solitary, pink-to-red plaques or nodules, but pigmented Spitz nevi are also commonly seen. Spitz nevi usually appear in children and young adults, they peak during the second and third decades of life, and are only rarely seen from the seventh decade to the ninth decade. Indpendently of ageprocess of becoming older, sex, location, palpability, and pigmentation of the lesion, most Spitz nevi tend to go through spontaneous involution over time. A majority of Spitz nevi exhibit an involution pattern over a period of 2 years. Spontaneous involution seems a plausible explanation for the epidemiologic data reporting the frequency of Spitz nevi as being inversely correlated to pa- tient age. The 2 main variants of Spitz nevi are the amelanotic and the pigmented ones.
Classic Spitz nevi are usually nonpigmented plaques or nodules commonly found on the faceis a central body region of sense and is also very central in the expression of emotion among humans and among numerous other species. and limbs of children and young adults. However, the spreadingThis glossary term has not yet been described. 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 allowed the recognition of an increasing number of pigmented Spitz nevi because of the unique morphologic features revealed by the dermatoscopeThis 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..
Most commonly the initial dermoscopic face of pigmented Spitz nevi is represented by a globular lesion which tends to acquire the classic starburst appearance after a variable number of months.
Starburst patternThis pattern consists of peripheral globules, pseudopods or streaks (or a combination of them), located around the entire perimeter of the lesion
The starburst patternThis pattern consists of peripheral globules, pseudopods or streaks (or a combination of them), located around the entire perimeter of the lesion is typified by streakslines radial (always at periphery) streaks Reed nevus melanoma recurrent nevus, pseudopodsBulbous and often kinked projections seen at the lesion edge, either directly associated with a network or solid tumor border., or finger-like projections regularly distributed on the periphery of an otherwise symmetric and hyperpigmented macule or plaque. The presence of streaks is not pathognomonic in Spitz nevi because they can also be found in melanoma, representing the behavior of a benign or malignant lesion by growing horizontally. In benign lesions like Spitz nevi, streaks tend to disappear over time as soon as the lesions stop growing. In this stable phase Spitz nevi are thus seen in dermoscopy as homogeneous, heavily pigmented lesions which can be more difficultneeding much effort or skill to accomplish to recognize.
Their homogenous pattern is typified by structureless brown- to-black pigmentation. Over a variable period of several months to a few years, a progressive decrease in pigment occurs until possible complete involution of the lesion is observed. Dermoscopic recognition of amelanotic Spitz nevi is much more difficult. Dotted vesselstiny pinpoint vessels, tan globulesThis glossary term has not yet been described., and reticular depigmentation are common findings but 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 should always be based on a combinationThis glossary term has not yet been described. of clinical and dermoscopic features.
After a growing phase of several months, the lesion starts to become smaller until it finally disappears. In conclusion, spontaneous involution seems to be by far the most common biologic behavior of both pigmented and nonpigmented Spitz nevi.