Phantom Tumors in COVID-19: A Case Report

a of a pleural effusion appearing as a phantom in of accompanied by and fatigue. shortness of and loss of and no habit and did not any medical history. Physical examinations were within normal limits, except for a slight fever. The laboratory examination showed positive SARS-CoV-2 RT-PCR and an increased liver function test. chest X-ray revealed findings suggestive of a phantom tumor accompanied by bilateral pneumonia. The patient received COVID-19 treatments. A follow-up chest X-ray revealed the complete resolution of the lesion. Conclusion: A phantom tumor is a rare case. It is not only caused by heart disease but also by other causes, one of which is COVID-19. The treatment for this condition is based on the underlying disease .


INTRODUCTION
Coronavirus disease 2019 (COVID- 19) was first identified in Wuhan in 2019 and was declared as a global pandemic on 11 March 2020 by the World Health Organization (WHO). The disease has been rapidly spreading worldwide with various new emerging variants.
Clinical manifestations vary from asymptomatic to acute respiratory distress syndrome (ARDS). Common symptoms include cough, fever, myalgia, headache, nausea and vomiting, and fatigue. The severity is based on clinical findings from physical examinations and radiography. Chest radiography is essential in patients with COVID-19. The typical chest radiograph findings in patients with COVID-19 include ground-glass opacities and consolidation, pneumatoceles, and vascular enlargement. Isolated pleural disease in COVID-19 is rare, and published reports have been scarce. The feature of pleural abnormalities might include thickening (15%) and effusion (4%) based on a study comparing CT scan findings. The incidence of pleural effusion in patients with COVID-19 has been unclear. Several studies stated that it is rarely encountered in patients with  However, the study by  reported that the incidence of pleural effusion in COVID-19 was 7.3%, while the study by Yu, et al. reported 12.9%. Another study reported an incidence of 2.6%, which further showed that the precise prevalence is still unknown. [1][2][3] As an atypical pleural effusion with interfissural distribution pleural effusion, a phantom tumor (vanishing lung pseudotumor) refers to the transient welldemarcated accumulation of pleural fluid in the interlobar pulmonary fissures. Chest X-rays usually reveal homogenous spherical-or elliptical-shaped opacities. It is generally associated with congestive heart failure and other disorders such as hypoalbuminemia, renal failure, hepatic failure, pneumonia, and tuberculosis or pleuritis. 4,5 The suggested disease mechanism is due to pleuritis, adhesion, and atelectasis.
The location of phantom tumors is usually in the rightmiddle lung region, although they have also been reported on the left side or adjacent to the mediastinum. [6][7][8] The transverse fissure is more involved than the oblique fissure. 5 Phantom tumors are commonly found within the minor fissure but can occur in low frequency within the major fissure. Furthermore, several studies have reported that the condition may recur in acute exacerbation of congestive heart failure. This finding further supported that phantom tumors are recurrent during periods of cardiac decompensation. 8 The correct diagnosis is important to avoid unnecessary and potentially harmful investigation and treatment (e.g., lung biopsy and/or surgery). 9,10 Although considered a type of pleural effusion, the prognosis of phantom tumors is not in line with typical pleural effusions in COVID-19. Pleural effusions in COVID-19 are also considered uncommon; however, the presence of pleural effusion in COVID-19 may reflect a more severe state with more prominent symptoms and lower oxygen saturation. They also indicate a risk of progression into ARDS, septic shock, and death. In contrast, phantom tumors are resolved quickly with the appropriate treatment of the underlying disease. [1][2][3]11 In this study, we reported a case of a 29-year-old man with a phantom tumor in COVID-19. This case is interesting since the finding of phantom tumors is already rare in patients without congestive heart failure, combined with the low prevalence of pleural effusion or pleural disease in patients with COVID-19. This is the first study that reported a phantom tumor case in a patient with COVID-19. The initial chest X-ray showed an oval-shaped homogenous opacity lesion in the middle of the right lobe ( Figure 1). The lesion was suspected to be a phantom tumor accompanied by bilateral pneumonia.

CASE
The patient received oral favipiravir tablets 1600 mg twice daily (BID) on day 1 of admission, followed by 600 mg BID on day 2 to day 5, azithromycin 500 mg once daily (OD), N-acetylcysteine 200 mg three times daily (TID), vitamin C 500 mg BID, vitamin D 5000 IU OD, and paracetamol 500 mg whenever he had fever.
After five days of treatment, the patient gradually began to recover, indicated by stable vital signs and physical examination. There was a blood pressure of 110/80 mmHg, a pulse of 87 beats/minute, a respiratory rate of 20 breaths/minute, a body temperature of 36.7°C, and oxygen saturation stable at 95%. Laboratory results were within normal limits, and a chest X-ray showed normal results on day 6 of admission ( Figure 2).

DISCUSSION
The term "phantom tumor" is derived from its appearance, which resembles a tumor on chest radiography and its tendency to quickly resolve (vanish) following the treatment. It was first reported by Gefter, et al. in 1950, which reported a localized interlobar pleural effusion appearing in patients with congestive heart failure. 11,12 In general, the phantom tumor was often found in patients with heart failure disorder. Nevertheless, in this case, we presented phantom tumors in patients with bilateral pneumonia in COVID-19, which are very rare. 13   In this case, we assumed that the phantom tumor in the patient was caused by pleuritis due to COVID-19.
Patients with pleural effusions related to COVID-19 often have abnormal laboratory results with elevated leukocytes, neutrophils, CRP, and procalcitonin. These conditions are also more commonly found in patients with more prominent COVID-19 symptoms, such as more severe cough, high fever, and dyspnea, often with significantly lower oxygen saturation. The low oxygen saturation in pleural effusions related to COVID-19 might be due to the disrupted respiratory function, which eventually worsens the condition and progresses into ARDS. The patient in this case, however, was presented with mild symptoms consisting of dry cough, sore throat, and fever. He had no shortness of breath, and the oxygen saturation was 95%, which revealed no signs of severe COVID-19. This finding is not in line with the presumed prominent symptoms of patients with COVID-19 complicated by pleural effusion, which further supported the diagnosis of vanishing pseudotumor (phantom tumors). 3 In order to facilitate clinicians in diagnosing and making different diagnoses for patients presenting with a pulmonary mass on chest radiograph, lateral views of chest X-ray should be obtained. These lateral views may facilitate localizing the pulmonary field. Chest ultrasound is also beneficial in differentiating effusions from masses. Currently, phantom tumors do not require more invasive or thorough imaging techniques for a definitive diagnosis. Rather, the diagnosis can be confirmed by a significant and rapid response to the treatment, particularly to diuretic therapies in patients with congestive heart failure or to antivirals or antibiotics in patients with infectious diseases. 11 In general, the most common cause of a phantom tumor is heart failure. Thus, treatment with diuretics provides good radiological improvement that can be observed in less than 24 hours after diuretic administration. 12 days after the initial chest X-ray that showed mass-like opacity, the patient in this case had a complete resolution on the follow-up chest X-ray. This finding is in line with the nature of phantom tumors based on the previous studies, which is the rapidly resolving condition after appropriate treatment for the underlying cause.

CONCLUSION
A phantom tumor is a rare case and is not only caused by heart disease but also by other causes, one of which is COVID-19. The treatment of this disease is based on the underlying disease. Accordingly, the patient in this case received COVID-19 treatments such as antivirals, antibiotics, symptomatic treatments, and multivitamins. Appropriate treatment generally results in rapid radiological improvement. In addition, it is important to be aware of this condition to avoid inappropriate, expensive, and potentially dangerous misdiagnosis and treatment, which might further harm the patient.

Consent
Written informed consent was obtained from the patient.