What is the management approach for a superficial biopsy showing changes consistent with an atypical spindle and epithelioid (Spitz) tumor?

Management of Atypical Spindle and Epithelioid (Spitz) Tumor

For a superficial biopsy showing changes consistent with an atypical spindle and epithelioid (Spitz) tumor, a conservative re-excision with 2-5 mm margins and long-term clinical follow-up is recommended as the standard management approach. 1

Diagnostic Evaluation Algorithm

When facing an atypical Spitz tumor diagnosis from a superficial biopsy, follow this stepwise approach:

1. Histopathological assessment: Review the biopsy for key melanoma-associated features:

   • Asymmetry
   • Lack of circumscription
   • Lack of maturation deep in the dermis
   • Ulceration
   • Deep dermal mitoses
   • High-grade cytological atypia
   • Brisk lymphocytic infiltrate 1

2. Immunohistochemical testing: If concerning histological features are present, perform:

   • Dual-color Ki67/MART-1 (to assess deep dermal proliferation)
   • p16 (to detect complete or partial loss)
   • HMB45 (to assess expression pattern) 1

3. Molecular/cytogenetic testing: If immunohistochemistry shows concerning features:

   • FISH testing for chromosomal aberrations (6p25, 8q24, 11q13, centromere 9, and 9p21)
   • If FISH is negative or borderline, proceed to array-based comparative genomic hybridization (aCGH) 1

Management Recommendations

For Typical Atypical Spitz Tumors (Low Risk)

If molecular testing shows no melanoma pattern of chromosomal aberrations:

• Conservative re-excision with 2-5 mm margins to ensure complete removal 1, 2
• Regular clinical follow-up with baseline photography documentation 2
• No sentinel lymph node biopsy is warranted for routine management of these lesions 3

For Spitzoid Melanoma (High Risk)

If testing reveals melanoma-pattern chromosomal aberrations (e.g., isolated homozygous loss of 9p21, isolated gain of 6p25, gain of 11q13, or loss of chromosome 9 with gain of 5q):

• Treat as melanoma with appropriate surgical margins and staging 1
• Consider sentinel lymph node biopsy based on standard melanoma protocols 1

Important Clinical Considerations

• Age factor: Atypical Spitz tumors predominantly affect children and young adults, with many occurring on the lower extremities 4, 5
• Nodal involvement: Atypical Spitz tumors may involve sentinel lymph nodes at a higher frequency than conventional melanoma, yet most still follow an indolent course 6
• Long-term outcomes: Studies of pediatric patients with atypical Spitz tumors treated with excision alone (without SLNB) showed no recurrence, additional lesions, or metastases after mean follow-up of 8.4 years 3

Common Pitfalls to Avoid

1. Overtreatment: Unnecessarily aggressive management can lead to excessive scarring and patient anxiety 2
2. Undertreatment: Failure to perform adequate molecular testing may miss cases of true spitzoid melanoma 1
3. Misinterpretation: Relying solely on histopathology without molecular testing can lead to diagnostic errors, as there is significant overlap between atypical Spitz tumors and melanoma 1, 6
4. Inadequate follow-up: These lesions require long-term monitoring even after complete excision 1

Remember that atypical Spitz tumors represent a diagnostic challenge with features overlapping between benign Spitz nevi and malignant spitzoid melanomas. The comprehensive diagnostic algorithm using immunohistochemistry and molecular testing helps stratify risk and guide appropriate management decisions.