Simplified Assessment of Radioiodine Biokinetics for Thyroid Cancer Patients: A Practical Approach Using Continuous External Radiation Monitoring.

INTRODUCTION: The biokinetics of radioiodine (RAI) in thyroid cancer patients are complex. This study aims to develop a practical approach for assessing RAI biokinetics to predict patient discharge time and estimate radiation exposure to caregivers. METHODS: We retrospectively reviewed data from patients with differentiated thyroid carcinoma undergoing RAI treatment. Serial radiation dose rates were dynamically collected during hospitalization and fitted to a biexponential model to assess the biokinetic features: RAI uptake fraction of thyroid tissue (Ft) and effective half-life of extra-thyroid tissue (Tet). Correlations with 99mTc thyroid uptake ratio (TcUR), radiation retention ratio (RR), renal function, and body mass index (BMI) were analyzed. RESULTS: Thirty-five patients were enrolled. The derived Ft was 0.08 ± 0.06 and Tet was 7.57 ± 1.45 h. Pearson's correlation analysis revealed a significant association between Ft and both TcUR and RR (p < 0.05), while Tet correlated with renal function and BMI (p < 0.05). CONCLUSION: This novel and practical method assessing RAI biokinetics demonstrates consistency with other parameters and related studies, enhancing the model reliability. It shows promise in predicting an appropriate discharge time and estimating radiation exposure to caregivers, allowing for modifications to radiation protection precautions to follow ALARA principle and minimize the potential risks from radiation exposure.

18 F-FDG PET/CT imaging for haemophilic arthropathy compared with clinical, radiological and power Doppler sonographic characteristics of 20 haemophilia patients.

INTRODUCTION AND OBJECTIVES: Repeated joint bleeding in haemophilia patients may lead to haemophilic arthropathy with marked inflammation and synovitis. This study investigated the potential of 18 F-fluorodeoxyglucose positron emission tomography-computed tomography (18 F-FDG PET/CT) as a novel diagnostic method for haemophilic arthropathy. MATERIALS AND METHODS: We recruited 20 adult haemophilia patients who reported history of hemarthroses in the shoulder, elbow, hip, knee, or ankle joints. All joints were assessed by power Doppler ultrasonography and radiography, and graded by hyperaemia score and Pettersson score, respectively. Joint pain was evaluated by visual analogue score (VAS). Range of motion (ROM), Haemophilia Joint Health Score (HJHS) and annual joint bleeding rate (AJBR) were recorded. Finally, all participants had whole-body 18 F-FDG PET/CT, and maximum standardized uptake value (SUVmax) of the joints being studied was measured. RESULTS: Thirteen patients had severe haemophilia, and seven had moderate haemophilia. The mean age was 36 years. PET SUVmax showed significant correlations with VAS, ROM, Pettersson score, hyperaemia score, HJHS score and AJBR in all large joints except hip. Joints with pain, hyperaemia and radiographic changes were found to have higher SUVmax than those without these features. Using Youden's index, the optimal cut-off value for early radiographical arthropathy was found to be between 1.9 and 2.0. CONCLUSION: Our study indicates that 18 F-FDG PET/CT imaging correlated well with various conventional diagnostic techniques. It also demonstrated high sensitivity and specificity for early radiographic arthropathy. 18 F-FDG PET/CT imaging may quantitatively evaluate disease activity of most large joints in a single examination and help detect early haemophilic arthropathy.

Radioactive Iodine Treatment for Thyroid Cancer Patients Increases the Risk of Long-Term Gastrointestinal Disorders: A Nationwide Population-Based Cohort Analysis.

(1) Background: The study aimed to investigate the association between radioactive iodine (RAI) treatment and long-term gastrointestinal disorders including ulcers, atrophic gastritis, and secondary malignant neoplasm of the stomach in patients with thyroid cancer. (2) Methods: The data of the study were extracted from the National Health Insurance Database (NHIRD) of Taiwan between 2000 to 2015. Patients of ages older than 20 with thyroid cancer after thyroidectomy were included and divided into groups with RAI (study cohort) and without RAI (comparison cohort). Multivariate Cox proportional hazards regression analysis and the Kaplan-Meier method were used for statistical analysis. (3) Results: A total of 7250 (with RAI: 5800, without RAI: 1450) patients were included. The Kaplan-Meier analysis revealed a significantly higher cumulative risk for overall gastrointestinal disorders in the group with RAI (log-rank p = 0.034). The risk for gastrointestinal disorders was higher when receiving a cumulative RAI dose higher than 1.11 GBq in the Cox regression analysis. In the subgroup analysis, the risks of gastric and duodenal ulcers are significantly higher in the group with RAI treatment. (4) Conclusions: This study revealed that RAI was associated with an increased risk for long-term gastrointestinal disorders, specifically gastric and duodenal ulcers, in thyroid cancer, especially when the cumulative dose exceeds 1.11 GBq.

Bezafibrate Exerts Neuroprotective Effects in a Rat Model of Sporadic Alzheimer's Disease.

Bezafibrate, a pan-peroxisome proliferator-activated receptor (PPAR) agonist, reportedly attenuated tau pathology in a transgenic mouse model of primary tauopathy. Since tau pathology is a neuropathological hallmark of Alzheimer's disease (AD), bezafibrate may be a potential drug for the treatment of AD. However, no study has investigated its effects in AD models. Thus, we aimed to evaluate whether bezafibrate has neuroprotective effects in a sporadic AD model induced by streptozotocin (STZ) intracerebroventricular (ICV) injection. Rats were administered STZ-ICV (3 mg/kg) followed by bezafibrate (50 mg/kg/day, intraperitoneal) for 4 weeks. Behavior tests and positron emission tomography (PET) were performed to evaluate longitudinal changes in cognitive function, tau pathology, and cerebral glucose metabolism. Immunofluorescence staining was performed to assess neuronal survival and microglial accumulation. STZ-ICV administration induced significant cognitive impairment and substantial neuronal loss, tau pathology, glucose hypometabolism, and microgliosis in the cortex and hippocampus, while bezafibrate effectively attenuated these abnormalities. This study demonstrated that bezafibrate has long-lasting neuroprotective effects in a sporadic AD model. Our data indicate that the neuroprotective effects of bezafibrate might be associated with its ability to ameliorate tau pathology, brain glucose hypometabolism, and neuroinflammation. These findings suggest that bezafibrate is a potential multi-target drug candidate for the treatment of AD.

Radioactive Iodine Treatment and the Risk of Long-Term Cardiovascular Morbidity and Mortality in Thyroid Cancer Patients: A Nationwide Cohort Study.

(1) Background: This study aimed to investigate the association between radioactive iodine (RAI) and long-term cardiovascular disease (CVD) morbidity/mortality in thyroid cancer. (2) Methods: The study was conducted using data from the Taiwan National Health Insurance Database during 2000-2015. Thyroid cancer patients aged ≥20 years were categorized into RAI (thyroidectomy with RAI) and non-RAI (thyroidectomy only) groups. The Cox proportional hazard regression model and Kaplan-Meier method were used for analysis. (3) Results: A total of 13,310 patients were included. Kaplan-Meier analysis demonstrated that the two groups had similar cumulative risks of CVD (log-rank p = 0.72) and CVD-specific mortality (log-rank p = 0.62). On Cox regression analysis of different RAI doses, the risk of CVD was higher in the cumulative dosage >3.7 GBq (hazard ratio = 1.69, 95% confidence interval = 1.24-2.40, p < 0.001). (4) Conclusions: RAI was not associated with an increased risk of CVD in thyroid cancer. However, CVD surveillance is indicated in the patients receiving the cumulative RAI dosage above 3.7 GBq.

A Pulmonary Pleomorphic Carcinoma Patient with Exudative Retinal Detachment Secondary to Choroid Metastasis as Initial Presentation-A Case Report.

Choroid metastasis is the initial presentation of pleomorphic carcinoma (PC) of the lung. PC is classified as poorly differentiated non-small cell lung carcinoma. It has a tendency to metastasize early and has a poor response to chemotherapy, which often results in poor prognosis. We report the case of a 63-year-old woman with a one-month history of deteriorating vision in the left eye. Fundus examination, fluorescein angiography, indocyanine green angiography, and B-scan sonography demonstrated choroidal metastasis of the left eye. Positron emission tomography/computed tomography (PET/CT) revealed a tumor with increased uptake in the left upper lung. Subsequent bronchoscopic biopsy confirmed a pleomorphic carcinoma of the lungs. Choroid metastasis as an initial presentation of PC in the lung is rare. Usually, it represents the late course of disseminated disease with hematogenous spread. Prompt diagnosis is imperative for patients to immediately initiate treatment.

Prognostic value of positron emission tomography in resected stage IA non-small cell lung cancer.

OBJECTIVES: To investigate the role of PET in predicting the prognosis of resected stage IA non-small cell lung cancer (NSCLC) and planning individualized therapeutic strategies. METHODS: We retrospectively reviewed the data of patients who underwent surgical resection for lung cancer between January 2004 and December 2014. The clinical data, imaging characteristics of nodules, surgical approaches, and outcomes were analyzed. RESULTS: We evaluated 998 cases; 637 patients with pathological stage I disease were categorized as follows: stage IA1 (251 cases), stage IA2 (250 cases), and stage IA3 (136 cases). The mean follow-up period was 109 months. Significant differences were observed in sex, tumor differentiation, epidermal growth factor receptor mutation, smoking habits, lymphovascular space invasion, tumor size, maximum standard uptake value (SUVmax), and carcinoembryonic antigen level among the groups. Multivariable Cox regression revealed that ground-glass opacity ratio (hazard ratio (HR) = 0.001) and tumor SUVmax independently predicted the postoperative risk of relapse for stage IA3 NSCLC. The HR for SUVmax > 4 was 8.986 (p < 0.001). The 5-year overall survival (OS) rates were 87.2%, 92.9%, and 82.7%, and the 5-year disease-free survival (DFS) rates were 93.2%, 84.2%, and 70.51% for stage IA1, IA2, and IA3 NSCLC, respectively (both p < 0.001). OS and DFS rates were poor in stage IA3 NSCLC patients with an SUVmax uptake > 4 (OS, 71.0% and 92.2%; DFS, 50.2% and 87.3%, for SUVmax > 4 and ≤ 4, respectively; both p = 0.001). CONCLUSIONS: SUVmax was a prognostic factor for resected stage IA NSCLC. Postoperative treatment may be considered for IA3 NSCLC with SUVmax > 4. KEY POINTS: • PET helps surgeons to assess patients with early-stage lung cancer. • This retrospective study revealed that PET plays an influential role in predicting the prognosis of resected lung cancer. • Better prognostication aids better planning of therapeutic strategies with diversification.

Image-based diagnosis of residual or recurrent nasopharyngeal carcinoma may be a phantom tumor phenomenon.

ABSTRACT: Some nasopharyngeal carcinoma (NPC) patients may present convincing radiological evidence mimicking residual or recurrent tumor after radiotherapy. However, by means of biopsies and long term follow-up, the radiologically diagnosed residuals/recurrences are not always what they appear to be. We report our experience on this "phantom tumor" phenomenon. This may help to avoid the unnecessary and devastating re-irradiation subsequent to the incorrect diagnosis.In this longitudinal cohort study, we collected 19 patients of image-based diagnosis of residual/recurrent NPC during the period from Feb, 2010 to Nov. 2016, and then observed them until June, 2019. They were subsequently confirmed to have no residual/recurrent lesions by histological or clinical measures. Image findings and pathological features were analyzed.Six patients showed residual tumors after completion of radiotherapy and 13 were radiologically diagnosed to have recurrences based on magnetic resonance imaging (MRI) criteria 6 to 206 months after radiotherapy. There were 3 types of image patterns: extensive recurrent skull base lesions (10/19); a persistent or residual primary lesion (3/19); lesions both in the nasopharynx and skull base (6/19). Fourteen patients had biopsy of the lesions. The histological diagnoses included necrosis/ inflammation in 10 (52.7%), granulation tissue with inflammation in 2, and reactive epithelial cell in 1. Five patients had no pathological proof and were judged to have no real recurrence/residual tumor based on the absence of detectable plasma EB virus DNA and subjective judgment. These 5 patients have remained well after an interval of 38-121 months without anti-cancer treatments.Image-based diagnosis of residual or recurrent nasopharyngeal carcinoma may be unreliable. False positivity, the "phantom tumor phenomenon", is not uncommon in post-radiotherapy MRI. This is particularly true if the images show extensive skull base involvement at 5 years or more after completion of radiotherapy. MRI findings compatible with NPC features must be treated as a real threat until proved otherwise. However, the balance between under- and over-diagnosis must be carefully sought. Without a pathological confirmation, the diagnosis of residual or recurrent NPC must be made taking into account physical examination results, endoscopic findings and Epstein-Barr virus viral load. A subjective medical judgment is needed based on clinical and laboratory data and the unique anatomic complexities of the nasopharynx.

Role and limitations of the geometric mean method regarding head rotation in salivary gland scintigraphy: a phantom study.

To investigate the possible influence of head rotation on the results of salivary gland scintigraphy, a phantom study was designed to simulate clinical salivary gland scintigraphy. The quantitative accuracy of regional activity counts was compared for two data acquisition methods involving head rotation: (i) an anterior planar projection-only (ANT) method and (ii) a geometric mean (GM) method using both the anterior and posterior planar projections. The roles and limitations of the GM and ANT methods when used at different head rotation angles were examined. Parallel planar projections of a head phantom with four salivary gland simulators, containing 3.7 MBq 99mTc-sodium pertechnetate, at various rotational settings were acquired using a dual-head gamma camera. The difference between the standard activity counts (no phantom rotation) and the activity counts affected by the phantom rotation was calculated and defined as the rotational bias that decreased the accuracy of activity quantification. For small-angle rotation (≤10°), use of the GM method decreased the bias for all salivary gland simulators. In contrast, the bias of large-angle rotation (>10°) between four salivary gland simulators became conspicuous and complex in both methods. This bias may reflect different attenuation effects caused by displacement of the structures. Our data suggest that the GM method can be used when the head rotation angle is small (≤10°); however, when the head rotation angle is >10°, the non-negligible influence of head rotation should be considered during image acquisition.

Paralytic ileus as the presenting symptom for Guillain-Barré syndrome: a case report.

Guillain-Barré syndrome (GBS) is an acute neuroimmunological disorder characterized by rapidly ascending symmetrical limb weakness, areflexia, and sensory deficits. Approximately 65% of patients with GBS present with autonomic dysfunction, which commonly occurs in advanced stages. However, paralytic ileus, a sign of gastrointestinal dysautonomia, is rare as the presenting feature in GBS before motor weakness becomes evident. We report the case of a 54-year-old man admitted to the Emergency Department with paralytic ileus as the prodromal feature in early-stage GBS. Total parenteral feeding and prokinetic use were initiated, but no clinical improvement was observed. The patient showed rapid progression to quadriplegia, which was ultimately determined to be respiratory muscle failure requiring mechanical ventilation and intensive care unit admission. He underwent 5 days of intravenous immunoglobulin therapy and muscle strength was partially improved thereafter. However, the patient's enteral nutritional support was undesirable because of persistent poor gastric emptying complicated by fungemia and profound sepsis throughout the hospital course. Finally, he died 1 month after admission. Ignorance of this unusual prodrome to GBS could result in delayed treatment, along with potential progression to life-threatening events. Early recognition of GBS and prompt immunotherapy are critical for reducing morbidity and mortality.

Uprighting a mesially tilted mandibular second molar by using a dental implant as anchorage: a case report / 华西口腔医学杂志

After tooth has been removed for a long time, adjacent teeth may tilt to occupy the edentulous space, leading to a break in the occlusal 3D equilibrium and a lack of restorative space. This case report presents a mandibular second molar uprighting with anchorage from a dental implant.

Positron emission tomography/computed tomography scan of Vogt-Koyanagi-Harada syndrome with associated autoimmune thyroid disease: A case report and literature review.

RATIONALE: Vogt-Koyanagi-Harada (VKH) syndrome is a rare disease and could be associated with autoimmune thyroid disease (AITD). This report was aimed to investigate the utility of F-fludeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) for the diagnosis of VKH syndrome with AITD and to perform a literature review on the association between the 2 diseases. PATIENT CONCERNS: A 55-year-old woman without the history of ocular trauma suffered from chronic headache. She was presented with painful blurred vision of both eyes with headache for 2 weeks. Ophthalmic evaluations revealed panuveitis, exudative retinal detachment, and papilloedema in both eyes. The clinical symptoms and presentations are compatible with the diagnosis of VKH syndrome. Other examinations for intraocular infection, malignancy, and lupus choroidopathy were of negative results. The result of contrast-enhanced computed tomography (CT) of the brain was normal. Due to the history of cancer in the patient's families, a F-FDG PET/CT whole-body scan was performed. The result indicated a focal of 2-fluoro-2-deoxy-D-glucose (FDG) uptake at the right upper lobe of the thyroid. Therefore, the patient's thyroid function was examined and the result indicated euthyroidism with detectable thyroid peroxidase/thyroglobulin antibodies. DIAGNOSES: VKH syndrome with associated AITD. INTERVENTIONS: Treatment with intravenous pulse systemic methylprednisolone (1000 mg daily) was prescribed for 3 days and then shifted gradually to tapered oral steroid medication. OUTCOMES: Symptoms of papillitis and serous retinal detachment of VKH syndrome was relieved after steroid treatment LESSONS:: F-fludeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) can be used for the effective diagnosis of VKH syndrome with AITD.

Chest Pain with Normal Thallium-201 Myocardial Perfusion Image - Is It Really Normal?

BACKGROUND: Thallium-201 myocardial perfusion image (MPI) is commonly used to detect coronary artery disease in patients with chest pain. Although a normal thallium-201 MPI result is generally considered to be a good prognosis and further coronary angiogram is not recommended, there are still a few patients who suffer from unexpected acute coronary events. The aim of this study was to investigate the clinical prognosis in patients with normal thallium-201 MPI. METHODS: From January 2006 to August 2012, a total 22,003 patients undergoing thallium-201 MPI in one tertiary center were screened. Of these, 8092 patients had normal results and were investigated retrospectively. During follow-up, 54 patients underwent coronary angiogram because of refractory typical angina pectoris or unexpected acute coronary events. These 54 patients were divided into 2 groups: group I consisted of 26 (48.1%) patients with angiography-proven significant coronary artery stenosis, and group II consisted of 28 (51.9%) patients without significant stenosis. RESULTS: Patients in group I had a higher prevalence of prior coronary stenting and electrocardiographic features of ST depression compared with patients in group II. The multivariate analysis demonstrated that both prior coronary stenting and ST depression were risk predictors of unexpected acute coronary events in the patients with normal thallium-201 MPI [odds ratio (OR), 5.93; 95% confidence interval (CI): 1.03-34.06, p = 0.05 and OR, 7.10; 95% CI: 1.28-39.51, p = 0.03,respectively]. CONCLUSIONS: Although there is a low incidence of unexpected acute coronary events in patients with chest pain and normal thallium-201 MPI, physicians should be aware of the potentials risk in certain patients in this specific population.

Lymphovascular space invasion and tumor differentiation are predictors for postoperative recurrence in patients with pathological stage I nonsmall cell lung cancer.

BACKGROUND: We investigated factors predicting postoperative recurrence in patients with pathological Stage I nonsmall cell lung cancer (NSCLC). METHODS: All patients with clinical Stage I NSCLC who underwent surgical resection at Tri-Service General Hospital in Taiwan between January 2002 and June 2006 were reviewed retrospectively. All study patients underwent standard staging workups. We reviewed the records of 261 patients with an average follow-up of 93 months; we then included 179 patients with pathological Stage I. RESULTS: Two hundred sixty-one patients with clinical Stage I NSCLC were eligible. There were no significant differences in sex, tumor histopathology, location, and age between the two groups (recurrence and nonrecurrence), except for tumor differentiation (p = 0.002), survival rate (p < 0.001), lymphovascular space invasion (LVSI; p = 0.007), advanced pathology stage (p = 0.022), maximum standard uptake value (SUVmax; p = 0.027), tumor size (p < 0.011), and carcinoembryonic antigen (CEA) levels (p = 0.013). Overall survival was significantly related to postoperative recurrence (p < 0.001) in patients with pathological Stage I, in whom recurrences developed in 11.17%. Only 179 patients with pathological Stage I NSCLC, including 20 patients with postoperative recurrences, were selected. Tumor differentiation (odds ratio 3.581, p = 0.058) and LVSI (odds ratio 5.374, p = 0.020) were independent factors predicting recurrence. CONCLUSION: Tumor differentiation and LVSI were predictors of postoperative relapse for patients with pathological stage I NSCLC. Risk factors of postoperative recurrence in patients with pathological Stage I NSCLC may enable us to optimize the patient selection for postoperative adjuvant therapies to prevent possibly occult micrometastases.

Experience of low-dose aminophylline use to relieve minor adverse effects of dipyridamole in patients undergoing stress myocardial perfusion imaging.

BACKGROUND: Intravenous administration of aminophylline is widely adopted to reverse dipyridamole-related adverse effects (AEs) during stress myocardial perfusion imaging (MPI). The study aimed to investigate the efficacy of lower-dose aminophylline to relieve minor AEs. METHODS: 2,250 consecutive patients undergoing dipyridamole-stressed MPI were enrolled. Information concerning AE occurrence and dosages of aminophylline was collected to evaluate the efficacy of lower-dose aminophylline. A logistic regression was used to determine independent predictors of dipyridamole-related AE occurrence. RESULTS: No severe AE was noted. Overall mild AE incidence was 37.0% (833/2,250 patients). Initial low-dose (25 mg) aminophylline relieved symptoms in 98.8% of patients with mild AEs (823/833 patients). An extra 25 mg aminophylline sufficed to reverse all such AEs. Mean body mass index (BMI) differed significantly between patients with and without any AE [25.6 vs 25.1 (P = .009)]. There was no significant difference between two subgroups in mean age, male gender prevalence, body height and weight, dipyridamole dose/BMI, or prevalence of significant perfusion defect(s) on MPI. Multivariable logistic regression demonstrated BMI remained the independent predictor of dipyridamole-related AE occurrence (odds ratio 1.028, 95% confidence interval 1.007-1.049, P = .01). CONCLUSION: Low-dose (≦50 mg, and usually 25 mg) aminophylline seems sufficient to relieve mild dipyridamole-related AEs during stress MPI.

Risk factors of postoperative recurrences in patients with clinical stage I NSCLC.

BACKGROUND: Despite advances in radiation therapy, chemotherapy, and newly developed molecular targeting therapies, long-term survival after resection for patients with NSCLC remains less than 50%. We investigated factors predicting postoperative locoregional recurrences and distant metastases in patients with clinical stage I non-small-cell lung cancer (NSCLC) after surgical resection. METHODS: All patients with clinical stage I NSCLC, who underwent surgical resection between January 2002 and June 2006, were reviewed retrospectively. Multiple logistic regression analyses were used to identify independent risk factors for patients with locoregional recurrences and distant metastases. RESULTS: A total of 261 patients were eligible. Overall survival was significant related to locoregional recurrences (P = 0.03) and distant metastases (P <0.001). There were significant differences of locoregional recurrence in tumor differentiation (P = 0.032) and advanced pathological stage (P = 0.002). In the group of distant metastases, there were significant differences in tumor differentiation (P = 0.035), lymphovascular space invasion (P = 0.031). Among the relationship between pattern of distant metastasis and clinicopathologic variables in patients with clinical stage I NSCLC, SUVmax (P = 0.02) and tumor size (P = 0.001) had significant differences. According to multiple logistic regression analysis, tumor differentiation is the only risk factor of postoperative outcome for locoregional recurrence and serum CEA (>3.5 ng/mL) is the predictor of distant metastasis. CONCLUSIONS: Tumor differentiation and serum CEA were predictors of postoperative relapse for clinical stage I NSCLC after surgical resection. Risk factors of postoperative recurrence in patients with clinical stage I NSCLC may enable us to optimize the patient selection for postoperative adjuvant therapies or neoadjuvant treatment before surgery.

"Quasi-symmetric" FDG avidity of bilateral salivary glands in Mikulicz disease yielding false-positive staging in lung cancer.

A 77-year-old man with lung cancer underwent fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). Cervical FDG uptake of variable intensity was detected corresponding to enlarged masses in the bilateral parotid and left submandibular regions. We suspected metastases from primary lung cancer or coexisting salivary gland neoplasms. Histopathological examination of the FDG-avid parotid mass revealed Mikulicz disease, an uncommon autoimmune disease involving the salivary glands. We present this case of Mikulicz disease with "quasi-symmetric" FDG avidity in the major salivary glands. We believe that salivary FDG uptake can lead to erroneous interpretation of tumor staging using PET.

Conversion from FDG-negative to -positive during follow-up in a rare case of pulmonary lymphoepithelioma-like carcinoma.

A female patient aged 75 years presented with an incidental pulmonary nodule without FDG uptake when undergoing FDG PET/CT. Without obtaining histologic diagnosis, the follow-up FDG PET/CT 2 years later demonstrated intense FDG avidity within previously FDG-negative tumor. After surgery, the pathologic diagnosis is pulmonary lymphoepithelioma-like carcinoma (LELC). LELCs are unique because of histologic similarities with undifferentiated nasopharyngeal lymphoepithelioma and with a better prognosis as compared with other lung malignancies. However, the expression of FDG uptake in LELC has never been discussed. Herein, we describe a pulmonary LELC manifesting as a slowly growing tumor displaying conversion from FDG-negative to -positive avidity.