Long-term Disease Control in Lung Adenocarcinoma with Recurrent Oligometastases: PET-guided Management

Intramedullary cauda equina metastases (ICEM) are rare lesions in patients with malignant tumors, accounting for <1% of all metastatic sites. We present a history of a 65-year-old female who achieved long disease-free survival (DFS) after local treatment of ICEM in the course of oligometastatic lung adenocarcinoma. More than 2 years after initial treatment (pneumonectomy and lymphadenectomy), the disease recurred with a single lesion in the contralateral lung. Stereotactic body radiation therapy (SBRT) guided by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) resulted in a complete metabolic response of the lung metastasis. Soon thereafter, the patient was diagnosed with hypopituitarism, and the magnetic resonance imaging (MRI) and FDG PET/CT revealed the presence of a focal lesion in the sella turcica, highly suspicious for metastatic pituitary adenocarcinoma. Again, the lesion was successfully treated with SBRT. After another year of follow-up, the patient developed low back pain accompanied by urine incontinence. MRI revealed a focal lesion in S2, which was resected and confirmed as adenocarcinoma metastasis. The following FDG PET/CT guided the adjuvant radiotherapy of the residual disease in the S1/S2 region. The DFS has so far reached over 24 months.