Atypical Spitz Tumor in a Pediatric Patient: A Case Report.

Introduction: Spitzoid neoplasms are a collection of melanocytic lesions distinguished from conventional nevi or melanoma by a unique set of histological and molecular features. These spitzoid proliferations - Spitz nevi, spitzoid melanocytoma, atypical Spitz tumors (ASTs), and spitzoid melanoma - range from benign to malignant. Morphology alone has been an insufficient prognostic tool, but immunohistochemical (IHC) stains prove useful for risk stratification. ASTs rarely metastasize beyond regional lymph nodes and treatment includes wide local excision (WLE) with or without sentinel lymph node (SNL) biopsy depending on histomolecular features. WLE of ASTs with negative margins is typically curative with excellent long-term survival and mortality rates close to zero in pediatric cases.

Case: A 12-year-old male presented to their pediatrician for a well child check without pertinent symptoms. Examination revealed a 5 x 4 mm elliptical, raised, red papule with asymmetric brown/black discoloration. He was referred to dermatology for evaluation. Five months later the lesion had grown to 11 x 6 mm covered with a pink/black crust. A shave biopsy displayed atypical spitzoid melanocytic proliferation but lacked significant staining with PRAME or BRAF. An ALK stain did not highlight the melanocytes upon further evaluation. These IHC findings are most consistent with an atypical Spitz tumor. A WLE with 5 mm margins was performed and margins revealed no residual melanocytic proliferation.

Conclusion: This case highlights the clinical, diagnostic, and management challenges of ASTs in pediatric patients. Although malignant potential is uncertain, ASTs often have an excellent prognosis with negative margins following WLE. In this case, IHC staining for PRAME and BRAF helped support the decision to defer SNL biopsy. This case underscores the importance of morphologic and molecular analysis to assess risk and guide management. Further research into molecular biomarkers may improve risk stratification and optimize treatment strategies for ASTs in pediatric patients.