INTRODUCTION: Femoral neuropathy is a rare condition typically resulting from compression of the femoral nerve. While it is commonly associated with anticoagulated patients due to psoas hematomas, spontaneous iliacus muscle hematomas without any evident trauma or coagulation disorders are exceedingly uncommon. This case report details the occurrence and management of a spontaneous iliacus muscle hematoma in an adolescent patient. Such cases have been scarcely reported, making this documentation critical for enhancing clinical understanding and management strategies. CASE REPORT: A 16-year-old male of Caucasian ethnicity, with no significant medical history, presented with thigh muscle atrophy, decreased strength in the left lower limb, and progressive loss of weight-bearing capacity over a month. The patient reported no history of trauma. Clinical examination revealed hypoesthesia in the femoral nerve territory and significantly reduced quadriceps muscle strength. Imaging studies, including magnetic resonance imaging, identified a fusiform mass deep to the left iliac muscle, consistent with an encapsulated hematoma. The patient was treated conservatively with rest and analgesics, followed by physical rehabilitation. Follow-up assessments showed progressive improvement in muscle trophism and weight-bearing capacity, with complete recovery of femoral nerve conduction at 1 year. CONCLUSION: This case underscores the importance of considering spontaneous iliacus muscle hematomas in the differential diagnosis of femoral neuropathy, even in the absence of trauma or anticoagulation therapy. The report highlights the necessity for thorough clinical evaluation and imaging to ensure accurate diagnosis. It adds valuable information to the orthopedic literature, particularly in managing rare presentations of femoral neuropathy, emphasizing the need for vigilance in monitoring and follow-up to prevent long-term complications. By detailing this unusual presentation, the report aims to enhance the understanding and treatment strategies for similar cases.