A 55–year–old male with a 20 pack year smoking history was diagnosed with stage IIIA (T2N2M0) non small (non squamous) cell carcinoma of the upper lobe of the left lung after presenting with weight loss and hemoptysis. He also complained of episodic sharp pain radiating down his right thigh over several weeks. While neurologic examination was benign, a 2–deoxy–fluoro–D–glucose PET/CT scan obtained for staging showed a small focus of activity in the anterior epidural space at the level of L1–2. An MRI confirmed a well–defined nodule measuring 8–9 mm in all dimensions in the right lateral ventral subarachnoid space (intradural, extramedullary). Based on imaging characteristics, location, and literature review suggesting potential PET positivity of schwannomas, the mass was designated to likely represent a benign schwannoma. Biopsy was considered, but felt to have moderate risk to the patient. Therefore, chemoradiation with carboplatin and docetaxel along with lung radiation therapy was initiated. During chemoradiation, the patient continued to have worsening right thigh and back pain. An MRI was repeated after 3 months, which revealed doubling of the size of the spinal lesion to 18 mm in maximum dimension. Metastasis thus became the diagnosis of exclusion. Prompt palliative radiation therapy was started. Symptoms continued to worsen with excruciating pain and paraesthesia, which led to surgical debulking of the tumor followed by completion of radiation. Histopathology confirmed metastatic non small cell lung cancer. The tumor subsequently metastasized to right anterior abdominal wall musculature and brain. Most recently, he presented with renewed progressive pain and MRI confirmed recurrence. He was treated with single fraction stereotactic ablative radiotherapy (SABR) to the lesion with prompt and complete pain relief. He continues to follow with his physicians.
Non small cell lung cancer (NSCLC) most commonly metastasizes to regional lymph nodes, contralateral lung, brain, liver and adrenal glands. Spinal metastases are seen in about 25% of cases. These are most commonly extradural (>98%, likely related to the dura mater acting as a physical barrier). In less than 2% metastasis can be in intradural extramedullary (IDEM) or intramedullary locations (primarily as drop metastasis from primary or secondary brain tumors). Our patient presented with a solitary IDEM metastasis in the absence of other metastatic disease in the setting of a primary non small cell lung cancer.
We present this case to encourage a tissue diagnosis in patients with NSCLC presenting with a pattern unusual for metastasis. Malignancy associated neurologic deficits have up to a 35% chance of permanent paraplegia and substantial progressive pain, which can be prevented by early aggressive local therapy including surgical removal or radiation therapy.