By Gary M. White, MD
A red plaque on the thigh of a child.
The Spitz nevus (SN) represents what used to be called benign melanoma or melanoma of childhood. These terms are no longer in use and should be avoided. It represents a proliferation of nevomelanocytic cells. It is usually benign, but unfortunately, some lesions which histologically showed the standard features of a Spitz nevus have metastasized, resulting in death. Multiple Spitz nevi may rarely occur grouped in one area (see agminated Spitz nevi). Because so few Spitz are seen in adulthood, it has been hypothesized that there is a histologic transition from Spitz nevus to compound nevus if left alone. Spitz nevis may occur in an agminated form or or present as multiple, eruptive lesions .
The Spitz nevus usually presents as a solitary, dome-shaped papule in a child. It is common on both the head and neck and the extremities. The majority of lesions are pink to red to amelanotic. Approximately 10% of SN are brown to black. It may be hard or soft in consistency, and solitary or rarely multiple (agminated). It is usually less than 1 cm in diameter and frequently less than 0.6 cm. It occasionally may bleed and be confused with a pyogenic granuloma.
In general, an experienced dermatopathologist should read these cases. STUMP lesions (Spitzoid tumor of uncertain malignant potential) can be very challenging histologically [JAAD 2011:64;559-5].
Dermoscopy is not so helpful for non-pigmented lesions. However pigmented Spitz nevi can have a very typical dermoscopy pattern. For moles with a globular pattern, the Brown and Black Rule states that: The globules in the compound nevus appear brown to brown-grey, while the globules in the Spitz nevus are brown, brown-grey and black [JEADV 2016;30;875].
Despite an abundance of research, Spitz nevus and melanoma cannot always be distinguished histologically. Many adjunctive techniques (e.g., immunohistochemistry, chromosome studies) have been studied as well, but none allows clear diagnosis of every lesion. The classic management approach has been that every presumed Spitz nevus should be completely excised if at all possible. More recently, many experts say that patients under 12 years of age with the classic Spitz nevus may be observed. In any case, if a biopsy is to be performed, it is best to remove the entire lesion.
At a national meeting in 2014, the question was asked, "What would you do for a 3 mm pink papule on the face of a 3-year-old that was clinically very typical for a Spitz nevus?" Many pediatric dermatologists responded that they would watch such a lesion. Others recommended surgical removal.
In a study of 384 lesions that clinically and dermoscopically appeared as typical Spitz nevi in patients 12 years and older, 13.3% were read as melanoma [JAAD 2015;72;47]. Increasing age was a significant risk factor, with 50% of lesions melanoma in those 50 years and older. The authors concluded that all Spitzoid-looking lesions in patients 12 and older should be surgically removed.
Another study showed that 80% of typical Spitz nevi (both pigmented and non-pigmented) in children spontaneous involuted with a mean follow up of 25 months [Dermatology 2011;222;256]. Thus, it appears that clinically typical lesions in children under 12 may be monitored for spontaneous involution.
If the histologic diagnosis is atypical Spitz nevus, complete excision (with e.g., a 3 mm histologic margin or 5 mm clinical margin) and close followup is recommended. In one review of 50 patients with atypical Spitz nevus, one patient died [JAAD 2015;72;37]. She was a 4-year-old girl with an incompletely excised primary lesion and no sentinel lymph node biopsy (SLNB). She experienced progression of disease 72 months after diagnosis and died at 96 months after diagnosis.
Some have defined a Spitzoid melanoma as "a malignant melanoma that is histologically similar to the benign Spitz nevus." Others have argued that the term Spitzoid melanoma not be used. Instead, they suggest the term "metastasizing Spitz tumor." Regardless of the nomenclature, the clinical approach to atypical spitzoid lesions/melanomas remains controversial. In what circumstances should one get a sentinel lymph node biopsy? What is the prognosis for a "spitzoid melanoma?" Should any adjunctive therapy be done?
This question is still controversial. Because the case fatality rate is low for Spitzoid melanoma, some experts lean against sentinel node biopsy unless "the pathologist says melanoma" or there is palpable lymphadenopathy.
In one study of 57 SLNB of Spitz [Cancer 2009 1;115;631], SLNB had no clinical benefit.
On the chest of a child.
Young woman in her 20's with a 5 mm red papule of 2 months duration of the thigh. It was read histologically as an atypical Spitzoid tumor and 5 mm margin excision recommended.