Atypical presentation of colorectal carcinoma with sole multiple osteolytic bone metastases: a case report

The incidence of colorectal cancer in persons aged < 50 years has been increasing. The diagnosis of colorectal cancer is not difficult if the patient has typical symptoms; however, diagnosis may be difficult in cases with atypical symptoms and signs. We present here an atypical case of metastatic colorectal cancer with fever and sudden onset paraplegia as the sole manifestations. The patient had multiple osteolytic lesions without gastrointestinal symptoms or signs, which resulted in a diagnostic delay of colorectal cancer.

A 46-year-old Japanese man was transferred to our hospital for evaluation of fever. He had developed fever 8 weeks previously and had been first admitted to another hospital 5 weeks ago. The patient was initially placed on antibiotics based on the suspicion of a bacterial infection. During the hospital stay, the patient experienced a sudden onset of paralysis and numbness in his both legs. Magnetic resonance imaging showed an epidural mass at the level of Th11, and the patient underwent a laminectomy. Epidural abscess and vertebral osteomyelitis were suspected, and antimicrobial treatment was continued. However, his fever persisted, and he was transferred to our hospital. Chest, abdominal, and pelvic computed tomography (CT) with contrast showed diffusely distributed osteolytic lesions. Fluorodeoxyglucose-positron-emission tomography showed high fluorodeoxyglucose accumulation in multiple discrete bone structures; however, no significant accumulation was observed in the solid organs or lymph nodes. A CT-guided bone biopsy obtained from the left iliac bone confirmed the evidence of metastatic adenocarcinoma based on immunohistochemistry. A subsequent colonoscopy showed a Borrmann type II tumor in the sigmoid colon, which was confirmed to be a poorly differentiated adenocarcinoma. As a result of shared decision-making, the patient chose palliative care.

Although rare, osteolytic bone metastases as the sole manifestation can occur in patients with colorectal cancer. In patients with conditions difficult to diagnose, physicians should prioritize the necessary tests based on differential diagnoses by analytical clinical reasoning, taking into consideration the patient's clinical manifestation and the disease epidemiology. Bone biopsies are usually needed in patients only with sole osteolytic bone lesions; however, other rapid and useful non-invasive diagnostic tests can be also useful for narrowing the differential diagnosis.