False-positive lung positron emission tomography-computed tomography result in a patient with a history of cancer

Chemical pleurodesis is an intrapleural administration of an sclerosing agent – talc, doxycycline or bleomycin. Talc is commonly used due to its high efficiency and low cost; in this form it is known as talc poudrage. This procedure is often used for patients with symptomatic pleural effusion associated, among other things, with cancer, and more rarely in recurrent spontaneous pneumothorax. Its aim is to induce a strong inflammatory response through mechanical and chemical irritation of the pleura and, consequently, to achieve symphysis between the two layers of pleura by sclerosing agents. However, talc is not metabolized by the tissues. Control imaging can imitate tumor growth, often giving false positive results in test interpretations if there are no notes recording this treatment.
The 56-year-old patient was admitted to the Pneumology Department of a local hospital with exertional dyspnea and the presence of fluid in the left pleural cavity which required further diagnosis and treatment. A chest X-ray showed an arched shaded left lung to the height of the front section of the fourth rib; above the shadowing, there was slight haze merging with the left niche; the right lung did not represent infiltrated or focal changes (Fig. 1). Bronchofiberoscopy showed evidence of a closure of the ostium of the lower left bronchial lobe by a hypertrophic change, partially covered with necrosis. The process also affected the lower spur. On the right side, all bronchial ostia were found to be clear of any pathological change. Scraps of bronchial tissue showed squamous cell carcinoma in a histopathological diagnosis. An ultrasound of the pleural cavity showed a large amount of fluid in the left pleural cavity. After an oncological consultation, initial chemotherapy (300 mg of paclitaxel and 600 mg of carboplatin) in four cycles every 3 weeks and radiation of 54 Gy to the mediastinum and 66 Gy to the tumor area and hilum was carried out. Four months after the end of cancer treatment, control positron emission tomography combined with computed X-ray tomography (PET-CT) revealed the presence of numerous atelectases in the middle of the left lung from the hilum to the back chest wall, showing metabolic impulse of SUV 3.66 (standardized uptake value). The left costophrenic angle showed areas of partially calcified clumps measuring 17 × 40 mm of SUV 10.57 adjacent to the lateral chest wall, from which a strip of thickened calcified pleura with excessive site reaction...


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