Introduction. Basal cell carcinoma, or basalioma, is the most common type of skin cancer. It typically develops on sun-exposed areas such as the head and neck, but occurrences on the abdomen are rare. Basal cell carcinoma is characterized by slow progression and low risk of metastases due to early detection and treatment. As a result, giant basal cell carcinomas, exceeding 5 cm in diameter, are uncommon. Case Report. We present the case of a 66-year-old woman diagnosed with basalioma. A decade earlier, she noticed a small skin lesion on her abdomen that gradually enlarged. By the time she sought medical attention, the lesion had reached 20 x 30 cm, infiltrating the anterior abdominal wall, muscles, and peritoneum. Surgical management included tumor excision, the elevation of two large transposition myocutaneous flaps, and coverage of residual skin defects with free partial-thickness skin transplants. At the three-month postoperative follow-up, no signs of recurrence were observed. However, the patient missed the subsequent check-ups for personal reasons, resulting in delayed detection of a recurrence. Two and a half years later, clinical examination revealed a local relapse. Magnetic resonance imaging identified two ulcerative lesions, measuring 7 cm and 9 cm in diameter, connected by a bridge-like tissue formation infiltrating deeper structures, including the liver capsule and intestinal walls. At this advanced stage, surgical intervention was deemed unfeasible. Conclusion. Although basalioma is typically detected and treated early, neglected cases can result in giant lesions with significant local invasion, and even organ involvement. Educating patients on the importance of adherence to follow-ups is essential to prevent such adverse outcomes.