Ann Nucl Med DOI 10.1007/s12149-014-0811-3
A case of septic pulmonary embolism associated with renal abscess mimicking pulmonary metastases of renal malignancy Jo Sung Jung • Sang Mi Lee • Han Jo Kim Si-Hyong Jang • Jeong Won Lee
Received: 19 November 2013 / Accepted: 13 January 2014 Ó The Japanese Society of Nuclear Medicine 2014
Abstract We report the case of a 46-year-old woman with acute febrile symptom who had multiple pulmonary nodules and a renal mass. She underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) to find a hidden malignancy and the cause of her fever. FDG PET/CT images demonstrated a renal mass and multiple lung nodules with intense FDG uptake, which was suspicious of a renal malignancy with multiple pulmonary metastatic lesions. CT-guided biopsies of the pulmonary and renal lesions only showed chronic inflammatory infiltrates without evidence of malignancy. She was diagnosed with septic pulmonary embolism from a renal abscess. One month after antibiotic treatment, the follow-up chest and abdomen CT showed improvement of the lung and renal lesions. This is the first case demonstrating the FDG PET/CT finding of septic
J. S. Jung Department of Radiology, Sooncheonhyang University Cheonan Hospital, Cheonan, Republic of Korea S. M. Lee (&) Department of Nuclear Medicine, Sooncheonhyang University Cheonan Hospital, 23-20 Byeongmyeong-dong, Dongnam-gu, Cheonan, Chungcheongnam-do, Republic of Korea e-mail: [email protected]
H. J. Kim Department of Internal Medicine, Sooncheonhyang University Cheonan Hospital, Cheonan, Republic of Korea
pulmonary embolism associated with renal abscess in the published literature. Keywords 18F-fluorodeoxyglucose PET Septic pulmonary embolism Renal abscess
Introduction Septic pulmonary embolism is an uncommon disorder that has non-specific clinical and radiological features [1, 2]. The diagnosis of septic pulmonary embolism is usually suggested by the presence of predisposing factors and clinical features such as fever with computed tomography (CT) findings including multiple lung nodules [2, 3]. Clinical and radiologic features at presentation are usually non-specific, and the diagnosis of septic pulmonary embolism is frequently delayed . Most cases of septic emboli originated from bacterial endocarditis or septic thrombophlebitis with infection sources such as periodontal inflammation, urinary tract infection, or infection of catheter [1, 2, 5]. Here, we report the case of a diabetic patient who showed multiple lung nodules and a renal mass with all the masses having increased 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT) mimicking metastatic lung nodules from a renal malignancy. To our knowledge, this is the first report of imaging finding of FDG PET/CT in a patient with septic pulmonary embolism from a renal abscess.
S.-H. Jang Department of Pathology, Sooncheonhyang University Cheonan Hospital, Cheonan, Republic of Korea
J. W. Lee Department of Nuclear Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
A 46-year-old woman presented with a 20 days history of cough and progressive left pleural pain prior to
Ann Nucl Med
admission. The patient was diagnosed with diabetes mellitus on the current year and was not on any medication. On admission, no other abnormal finding was found on physical examination. Laboratory studies revealed an elevated white blood cell count (11,290/mm3; normal range 4,000–10,800/mm3) and elevated serum C-reactive protein level (45.59 mg/L; normal range 0.01–3.0 mg/L). Diabetes laboratory analyses showed increased blood glucose (222 mg/dL) and hemoglobin A1c (10.3 %) levels. The chest X-ray demonstrated multiple pulmonary nodules with pleural effusion in the right hemithorax (Fig. 1a), and further work-up with contrast-enhanced CT scan was performed to evaluate multiple pulmonary nodules. Chest CT revealed welldefined variable-sized multiple nodular lesions, some containing cavity, in both lung fields (Fig. 1b, c) with bilateral pleural effusion. In addition, a 4.6-cm-sized heterogeneously contrast-enhanced mass was detected in the left kidney on abdominal CT scan (Fig. 1d). The echocardiography result was within normal limits. To find out other abnormal lesion and to differentiate malignant lesions, FDG PET/CT was performed. At the time of FDG PET/CT scan, the patient had fever of 39.8 °C with general weakness. The FDG PET/CT showed multiple lung nodules with increased FDG uptake [maximum standardized uptake value (SUVmax) of 5.6] and a left renal mass with intense FDG uptake (SUVmax of 8.9) (Fig. 2).
Fig. 1 Chest X-ray (a) shows multiple nodular opacities in both lung fields. Chest CT scan (b and c) shows multiple welldefined heterogeneously enhanced nodules and cavitary lesions in both lung fields, and a 4.6-cm-sized mass lesion was seen in the left kidney on abdomen CT images (d)
These findings on PET/CT images could be interpreted as septic pulmonary embolism due to renal abscess, which could explain the fever, but metastatic lung nodules due to renal malignancy should also be suspected. After PET/CT scan, CT-guided biopsies of the pulmonary and renal lesions were performed for histopathological diagnosis. The biopsy specimen from the lung and kidney revealed infiltration of chronic inflammatory cells and fibroblastic proliferation without evidence of malignant cell. Moreover, culture of sample from the urogenital tract was positive for Gram-positive cocci (Enterococcus faecium). She was eventually diagnosed with septic pulmonary embolism originating from a renal abscess. She was promptly treated with antibiotics (metronidazole and ceftriaxone). Follow-up chest X-ray, and chest and abdomen CT images (Fig. 3) performed 3 months after the treatment showed regression of the lung nodules and left renal lesion.
Discussion Although septic pulmonary embolism is a fatal condition, it being uncommon along with the vague and non-specific clinico-radiologic findings often leads to misdiagnosis [1, 2]. Most cases of septic pulmonary embolism occur in patients with tricuspid valve endocarditis, indwelling
Ann Nucl Med Fig. 2 The FDG PET/CT images for the work-up of pulmonary and renal lesions. Multiple pulmonary lesions and left renal mass with increased FDG uptake are shown on maximal intensity projection (a) and transaxial PET/CT images of the chest (b and c), and abdomen (d)
catheter, pace-maker wires, peripheral septic thrombophlebitis, and infection after organ transplantation . A renal abscess has been shown to be extremely rare cause of septic pulmonary embolism. The previous largest clinical study involving 247 septic pulmonary embolism cases demonstrated that the main causes of septic pulmonary embolism were pneumonia, sepsis, and infectious endocarditis. None of the cases was due to a renal abscess . There were only two case reports of septic pulmonary embolism from a renal abscess [4, 7], and none have shown the FDG PET/CT findings of septic pulmonary embolism caused by a renal abscess. In the present case, contrastenhanced CT scan and FDG PET/CT revealed no abnormal finding, other than the renal abscess, which could be the source of the septic pulmonary embolism. The echocardiography revealed no abnormal finding. The diagnosis was confirmed with the histopathology of the pulmonary and renal lesions showing inflammation and isolation of the causative organism (Enterococcus faecium) from the urogenital tract.
The CT finding of this case showed multiple welldefined and enhancing nodules in both lung fields. Although multiple peripheral nodules in both lung fields are the most common CT finding of septic pulmonary embolism [3, 8], FDG PET/CT was performed to find the origin of the fever because renal abscess is a rare cause of septic pulmonary embolism and to rule out the possibility of malignant lesion. Along with the clinical usefulness of FDG PET/CT in malignant disease, its usefulness in fever work-up has also been reported . A renal malignancy with multiple pulmonary metastases was suspected when the FDG PET/CT images showed intense FDG uptake by the left renal mass and multiple lung nodules. Since FDG accumulation not only occurs in malignant tissues but also focuses on inflammation, further work-up such as histopathological confirmation is needed. In this case, the biopsies revealed chronic inflammatory condition in the lung and kidney. The previously reported cases with septic pulmonary embolism also showed intense FDG uptake by the
Ann Nucl Med Fig. 3 The 3-month follow-up chest X-ray and CT images after antibiotics medication. Chest X-ray (a) showing no abnormal lung lesion. Chest CT (b and c) shows decrease in size of the pulmonary nodules, and abdomen CT (d) reveals decreased size of the left renal mass
pulmonary lesions [10, 11]. The possibility of benign inflammatory lesions should be considered even though multiple pulmonary nodules show intense FDG uptake. In addition, other nuclear imaging such as pulmonary perfusion single photon emission computed tomography (SPECT)/CT could help the diagnosis of septic pulmonary embolism . Septic pulmonary embolism is associated with several risk factors such as intravenous drug use, bacterial endocarditis, catheter insertion, and diabetes mellitus [2, 4]. Among the risk factors mentioned above, diabetes mellitus is known to be the most frequent comorbid factor . The patient in our case was also diagnosed with diabetes mellitus. She was not taking any diabetes medication and the result of her HbA1c revealed that her diabetes is uncontrolled. Physicians should consider septic pulmonary embolism when there are predisposing factors such as diabetes or the patient being in an immunocompromised state accompanied by evidence of infection and radiographic abnormality. We report the first case of a patient with septic pulmonary embolism that originated from a renal abscess which showed intense FDG uptake on FDG PET/CT images, mimicking renal malignancy with multiple pulmonary metastases. Hence, careful assessment should be performed even though multiple pulmonary nodules with intense FDG uptake are found.
Acknowledgments This work was supported in part by the Soonchunhyang University Research Fund.
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