P27. Small cell lung cancer and combined sparoganosis were suspected by multiple distant metastasis in PET-CT imaging of patient with colon cancer

Background: F-18 fluorodeoxyglucose (FDG) combined position emission tomography/computed tomography (PET/CT) imaging is frequently used in the surveillance of recurrent colorectal cancer and distant metastasis. We report a primary small cell lung cancer and combined parasite infection were suspected by distant multiple metastasis of colon cancer in a patient with history with treatment of colon cancer in PET-CT imaging.

Material and methods: F-18 FDG PET/CT imaging of a patient with a curative laparoscopic anterior resection done 13 months ago showed a faint hot uptake of pulmonary nodule within the right upper lobe and a focal faint hypermetabolic lesion within the right latissimus dorsi muscle, and hot uptakes in mediastinal lymph nodes (LNs). The level of serum carcinoembryonic antigen (CEA) level is within normal range. We thought that pulmonary metastasis of colon cancer was possible, however a distant metastasis of colon cancer within right latissimus dorsi muscle was very rare and unusual. So this patient had undergone complete excision of soft tissue nodule and video assisted thoracoscopic wedge resection with mediastinal lymph node sampling.

Results: Pulmonary nodule was diagnosed as primary small cell lung cancer with neuroendocrine feature. Soft tissue nodule was parasite infection, sparoganosis. Mediastinal LNs were benign. He was treated with chemotherapy and then prophylactic cranial radiotherapy. There is no evidence of cancer recurrence nor recurrent sparoganosis during 18 months follow-up period.

Conclusions: The multiple hot uptakes in PET-CT imaging in cancer patient were suspected by distant metastasis. However a false positive in PET-CT imaging is possible in other primary tumor, benign inflammation as parasite infection. Therefore to reach exactly accurate diagnosis is that the biopsy or excision of suspicious lesions is very important.

Keywords: Non-small cell lung cancer (NSCLC); position emission tomography/computed tomography (PET-CT); infection