Résumé

Introduction: Juvenile melanoma is a rare malignant tumor arising from melanocytes in individuals under 19 years of age. It accounts for 1–3% of pediatric cancers and most commonly affects the trunk and extremities. Diagnosis is frequently delayed because of its atypical clinical presentation, particularly in patients with dark skin, resulting in a poorer prognosis. We report a case of buttock melanoma in a 15-year-old girl with phototype VI. Case Report: A 15-year-old girl with phototype VI and no significant medical history presented with a one-year history of a progressively enlarging left buttock mass. Clinical examination revealed a smooth, rounded, vascularized subgluteal mass measuring 5 cm. Simple surgical excision was performed. Histopathological examination demonstrated a malignant proliferation of atypical melanocytes infiltrating the reticular dermis, with a Breslow thickness of 15 mm and Clark level V. Immunohistochemistry showed diffuse S100 positivity, confirming the diagnosis of melanoma. No staging investigations or sentinel lymph node biopsy were performed because melanoma was not suspected preoperatively, and the patient was subsequently lost to follow-up. Discussion: Pediatric melanoma is an exceptionally rare malignancy, with an estimated incidence of 5–6 cases per million children annually. It predominantly affects Caucasian populations and is uncommon in individuals with phototype VI, in whom acral sites are the usual locations. In children, the classic ABCDE criteria are often absent, as lesions may be amelanotic, nodular, or mimic benign tumors, contributing to delayed diagnosis. Histopathological examination, supported by immunohistochemistry, remains the cornerstone of diagnosis. Prognosis depends mainly on Breslow thickness, Clark level, ulceration, and lymph node involvement. In the present case, the absence of adequate surgical margins, staging investigations, and sentinel lymph node biopsy—due to limited resources and loss to follow-up—represented major adverse prognostic factors. Optimal management includes wide local excision, lymph node assessment, stage-adapted adjuvant therapy, and long-term surveillance. Conclusion: Juvenile melanoma is a rare malignancy whose diagnosis is particularly challenging in patients with dark skin because of its atypical clinical presentation. This case highlights the diagnostic and therapeutic challenges encountered in resource-limited settings. Early clinical suspicion, histopathological confirmation with immunohistochemistry, and guideline-based management are essential to improve patient outcomes.

Mot-clés :

Juvenile Melanoma; Pediatric Melanoma; Phototype Vi; Immunohistochemistry; Resource-Limited Settings