Vertebral Metastasis as the Initial Manifestation of Colon Cancer

Abstract

Introduction: Traditionally, colon cancer is not thought to metastasize to bone, unlike breast, prostate, or lung cancers. In fact, both United States and European cancer society guidelines recommend against endoscopy in the work-up of adenocarcinoma of unknown primary, unless otherwise suggested by clinical symptoms, laboratory, or imaging findings. We would like to present 2 cases of colorectal cancer that presented solely as bony metastases. Case 1: A 34-year-old female presented with bilateral lower extremity paralysis and numbness for 1 day. The patient had an 8-month history of back pain. An MRI 1 month prior at an outside hospital showed a T11 vertebral lesion causing spinal canal stenosis and cord compression. She received outpatient follow-up until this new onset of symptoms, when she was transferred to our hospital for further management. Upon presentation, she was taken emergently for T10-11 laminectomy with biopsy of the vertebral lesion, which revealed adenocarcinoma. Subsequent CT of the chest, abdomen, and pelvis showed a 4.5-cm ascending colon mass, but no other signs of metastases. Colonoscopy with biopsy confirmed primary colonic adenocarcinoma. Case 2: A 61-year-old female presented with worsening pain and numbness of her upper extremities. Two months prior in Russia, she experienced severe neck pain, leading to discovery of a C5-6 compression fracture. She underwent decompression with a vertebral biopsy, which revealed adenocarcinoma. CT scans then revealed several pulmonary nodules, enlarged mediastinal lymph nodes, and lytic skull foci. Upon presentation to our hospital, spine MRI revealed cervical lesions and a T3 lesion with cord compression. CT scans for staging of her adenocarcinoma of unknown primary again revealed pulmonary nodules, as well as 4 hepatic metastases up to 2 cm and a 15-cm sigmoid colonic thickening concerning for neoplasm. Colonoscopy with biopsy confirmed primary colonic adenocarcinoma. Discussion: Based on the medical literature, colorectal cancer rarely metastasizes to bone. Studies with chart review of medical or autopsy records have reported an incidence of 2-24% and even lower, 1-2%, for isolated bony metastasis. Further, the bone metastases were almost always discovered after initiation of treatment for the colorectal cancer. Herein, we present 2 patients without gastrointestinal symptoms who both presented with spinal cord compression from vertebral metastases of adenocarcinoma, later revealed to originate from a colonic source. While we acknowledge its rare occurrence, these 2 cases underscore the importance of having colon cancer on the differential diagnosis for adenocarcinoma of unknown primary in the bone.