Integrating 31-Gene Expression Profiling in a Spitzoid Melanocytic Lesion: A Case Report in a 24-Year-Old Patient

Diagnosing melanocytic lesions such as Spitz nevi, atypical melanocytic proliferations, and melanoma can be particularly challenging due to overlapping clinical and histopathologic features. In such cases, MyPath is designed to aid in diagnosis of ambiguous melanocytic lesions. In contrast, DecisionDx-Melanoma is not used for diagnostic uncertainty but for prognostic risk stratification in patients with Stage I-III invasive cutaneous melanoma. We present the case of a 24-year-old Caucasian female with an atypical melanocytic proliferation exhibiting spitzoid features on the left medial knee. Biopsy showed a malignant melanoma (Breslow depth 0.4 mm), and a wide local excision was performed. Additional spitzoid lesions were identified, as well as two melanoma in situs. Molecular testing of the primary lesion on the patient’s knee using the 31-gene expression profile (31-GEP) classified the tumor as Class 1A, indicating a low risk of metastasis and a melanoma-specific survival rate of 99.9%. This test provided valuable insight into sentinel lymph node biopsy (SLNB) risk and overall prognosis. This case underscores the value of molecular testing in guiding clinical decision-making and surveillance while minimizing overtreatment.