Atypical/Borderline and Malignant Spitz Tumors

 Most patients have good prognosis, with only minority of cases progressing to systemic disease or death






Microscopic




• Severely atypical/borderline Spitz tumor
image Typically, large and deep cellular compound melanocytic tumors

image May appear symmetric and well circumscribed at low power

image Cells show severe cytologic atypia with nuclear hyperchromasia, enlarged nucleoli, irregular chromatin, and abundant amphophilic or dense eosinophilic cytoplasm

image Mitotic figures often present, increased compared to conventional Spitz nevi

• Spitzoid melanoma
image Also large and deep tumors

image Frank atypia and pleomorphism present

image Junctional component often shows irregular nesting, confluence, and prominent pagetoid upward scatter

image Multiple mitotic figures usually present

image Often atypical &/or deep

image
Clinical Photograph of Atypical Spitz Tumor
This is an atypical compound Spitz tumor on the buttock of a 16-year-old patient. Despite the clinically banal appearance, there was severe cytologic atypia and multiple dermal mitotic figures identified, histologically.


image
Severely Atypical Spitz Tumor
This severely atypical compound Spitz tumor shows a predominantly intradermal population of atypical spindled cells with nuclear enlargement, hyperchromasia image, and focally prominent nucleoli.

image
Spitzoid Melanoma
This is an example of spitzoid melanoma in a young adult. The dermal cells are markedly enlarged, atypical, and pleomorphic appearing. In addition, there are multiple mitotic figures in this field image.

image
HMB-45 Immunohistochemistry in Spitzoid Melanoma
This spitzoid melanoma shows strong HMB-45 staining in the dermis. Although not always positive, strong dermal HMB-45 expression in an atypical melanocytic proliferation should raise suspicion for melanoma.


TERMINOLOGY


Abbreviations




• Atypical Spitz tumor (AST)


Synonyms




• Atypical spitzoid melanocytic proliferation

• Spitz tumor of borderline/uncertain malignant potential

• Spitzoid melanoma


Definitions




• Atypical/borderline Spitz tumor: Severely atypical melanocytic proliferation with features intermediate between Spitz nevus and spitzoid melanoma

• Malignant Spitz tumor: Malignant melanocytic proliferation with spitzoid features


ETIOLOGY/PATHOGENESIS


Unknown




• Typically occur in young patients without any known risk factors for melanoma

• Sun exposure may be risk factor in some cases


Possible Genetic Role




• Suggested by chromosome 11p amplification in minority of Spitz nevi

• Complex chromosomal alterations typically seen in melanoma


CLINICAL ISSUES


Epidemiology




• Incidence
image Very rare tumors

• Age
image Mostly young patients; range: 2-30 years

image Malignant tumors more common in postpuberty


Presentation




• Dermal papule or nodule


Treatment




• Surgical approaches
image Complete and wider excision is standard therapy

– Typically ≥ 5-mm clinical margins for atypical/borderline tumors

– Spitzoid melanomas should be treated with same margins as invasive melanomas of same Breslow depth

image Sentinel lymph node biopsy remains controversial

– Should be considered prognostic rather than therapeutic procedure at this time

– Controversial but likely should not be routinely used (especially for atypical/borderline tumors) until validated by more extensive clinical studies


Prognosis




• Difficult to predict
image Most patients have relatively good prognosis, with only minority of cases progressing to metastasis and death

image Even patients with lymph node involvement often have relatively good prognosis, as most tumors do not disseminate further


MICROSCOPIC


Histologic Features



Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Atypical/Borderline and Malignant Spitz Tumors
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