Impact of Mediastinal Lymphadenopathy on the Severity of COVID-19 Pneumonia: A Nationwide Multicenter Cohort Study

Background@#We analyzed the differences between clinical characteristics and computed tomography (CT) findings in patients with coronavirus disease 2019 (COVID-19) to establish potential relationships with mediastinal lymphadenopathy and clinical outcomes. @*Methods@#We compared the clinical characteristics and CT findings of COVID-19 patients from a nationwide multicenter cohort who were grouped based on the presence or absence of mediastinal lymphadenopathy. Differences between clinical characteristics and CT findings in these groups were analyzed. Univariate and multivariate analyses were performed to determine the impact of mediastinal lymphadenopathy on clinical outcomes. @*Results@#Of the 344 patients included in this study, 53 (15.4%) presented with mediastinal lymphadenopathy. The rate of diffuse alveolar damage pattern pneumonia and the visual CT scores were significantly higher in patients with mediastinal lymphadenopathy than in those without (P < 0.05). A positive correlation between the number of enlarged mediastinal lymph nodes and visual CT scores was noted in patients with mediastinal lymphadenopathy (Spearman’s ρ = 0.334, P < 0.001). Multivariate analysis showed that mediastinal lymphadenopathy was independently associated with a higher risk of intensive care unit (ICU) admission (odds ratio, 95% confidence interval; 3.25, 1.06-9.95) but was not significantly associated with an increased risk of in-hospital death in patients with COVID-19. @*Conclusion@#COVID-19 patients with mediastinal lymphadenopathy had a larger extent of pneumonia than those without. Multivariate analysis adjusted for clinical characteristics and CT findings revealed that the presence of mediastinal lymphadenopathy was significantly associated with ICU admission.

Korean Clinical Imaging Guidelines for the Appropriate Use of Chest MRI

MRI has the advantages of having excellent soft-tissue contrast and providing functional information without any harmful ionizing radiation. Although previous technical limitations restricted the use of chest MRI, recent technological advances and expansion of insurance coverage are increasing the demand for chest MRI. Recognizing the need for guidelines on appropriate use of chest MRI in Korean clinical settings, the Korean Society of Radiology has composed a development committee, working committee, and advisory committee to develop Korean chest MRI justification guidelines. Five key questions were selected and recommendations have been made with the evidence-based clinical imaging guideline adaptation methodology.Recommendations are as follows. Chest MRI can be considered in the following circumstances:for patients with incidentally found anterior mediastinal masses to exclude non-neoplastic conditions, for pneumoconiosis patients with lung masses to differentiate progressive massive fibrosis from lung cancer, and when invasion of the chest wall, vertebrae, diaphragm, or major vessels by malignant pleural mesothelioma or non-small cell lung cancer is suspected. Chest MRI without contrast enhancement or with minimal dose low-risk contrast media can be considered for pregnant women with suspected pulmonary embolism. Lastly, chest MRI is recommended for patients with pancoast tumors planned for radical surgery.

Prognostic Implications of CT Feature Analysis in Patients with COVID-19:a Nationwide Cohort Study

Background@#Few studies have classified chest computed tomography (CT) findings of coronavirus disease 2019 (COVID-19) and analyzed their correlations with prognosis. The present study aimed to evaluate retrospectively the clinical and chest CT findings of COVID-19 and to analyze CT findings and determine their relationships with clinical severity. @*Methods@#Chest CT and clinical features of 271 COVID-19 patients were assessed. The presence of CT findings and distribution of parenchymal abnormalities were evaluated, and CT patterns were classified as bronchopneumonia, organizing pneumonia (OP), or diffuse alveolar damage (DAD). Total extents were assessed using a visual scoring system and artificial intelligence software. Patients were allocated to two groups based on clinical outcomes, that is, to a severe group (requiring O2 therapy or mechanical ventilation, n = 55) or a mild group (not requiring O2 therapy or mechanical ventilation, n = 216). Clinical and CT features of these two groups were compared and univariate and multivariate logistic regression analyses were performed to identify independent prognostic factors. @*Results@#Age, lymphocyte count, levels of C-reactive protein, and procalcitonin were significantly different in the two groups. Forty-five of the 271 patients had normal chest CT findings. The most common CT findings among the remaining 226 patients were groundglass opacity (98%), followed by consolidation (53%). CT findings were classified as OP (93%), DAD (4%), or bronchopneumonia (3%) and all nine patients with DAD pattern were included in the severe group. Uivariate and multivariate analyses showed an elevated procalcitonin (odds ratio [OR], 2.521; 95% confidence interval [CI], 1.001–6.303, P = 0.048), and higher visual CT scores (OR, 1.137; 95% CI, 1.042–1.236; P = 0.003) or higher total extent by AI measurement (OR, 1.048; 95% CI, 1.020–1.076; P < 0.001) were significantly associated with a severe clinical course. @*Conclusion@#CT findings of COVID-19 pneumonia can be classified into OP, DAD, or bronchopneumonia patterns and all patients with DAD pattern were included in severe group. Elevated inflammatory markers and higher CT scores were found to be significant predictors of poor prognosis in patients with COVID-19 pneumonia.

Korean Clinical Imaging Guidelines for the Appropriate Use of Chest MRI

MRI has the advantages of having excellent soft-tissue contrast and providing functional information without any harmful ionizing radiation. Although previous technical limitations restricted the use of chest MRI, recent technological advances and expansion of insurance coverage are increasing the demand for chest MRI. Recognizing the need for guidelines on appropriate use of chest MRI in Korean clinical settings, the Korean Society of Radiology has composed a development committee, working committee, and advisory committee to develop Korean chest MRI justification guidelines. Five key questions were selected and recommendations have been made with the evidence-based clinical imaging guideline adaptation methodology.Recommendations are as follows. Chest MRI can be considered in the following circumstances:for patients with incidentally found anterior mediastinal masses to exclude non-neoplastic conditions, for pneumoconiosis patients with lung masses to differentiate progressive massive fibrosis from lung cancer, and when invasion of the chest wall, vertebrae, diaphragm, or major vessels by malignant pleural mesothelioma or non-small cell lung cancer is suspected. Chest MRI without contrast enhancement or with minimal dose low-risk contrast media can be considered for pregnant women with suspected pulmonary embolism. Lastly, chest MRI is recommended for patients with pancoast tumors planned for radical surgery.

Prognostic Implications of CT Feature Analysis in Patients with COVID-19:a Nationwide Cohort Study

Background@#Few studies have classified chest computed tomography (CT) findings of coronavirus disease 2019 (COVID-19) and analyzed their correlations with prognosis. The present study aimed to evaluate retrospectively the clinical and chest CT findings of COVID-19 and to analyze CT findings and determine their relationships with clinical severity. @*Methods@#Chest CT and clinical features of 271 COVID-19 patients were assessed. The presence of CT findings and distribution of parenchymal abnormalities were evaluated, and CT patterns were classified as bronchopneumonia, organizing pneumonia (OP), or diffuse alveolar damage (DAD). Total extents were assessed using a visual scoring system and artificial intelligence software. Patients were allocated to two groups based on clinical outcomes, that is, to a severe group (requiring O2 therapy or mechanical ventilation, n = 55) or a mild group (not requiring O2 therapy or mechanical ventilation, n = 216). Clinical and CT features of these two groups were compared and univariate and multivariate logistic regression analyses were performed to identify independent prognostic factors. @*Results@#Age, lymphocyte count, levels of C-reactive protein, and procalcitonin were significantly different in the two groups. Forty-five of the 271 patients had normal chest CT findings. The most common CT findings among the remaining 226 patients were groundglass opacity (98%), followed by consolidation (53%). CT findings were classified as OP (93%), DAD (4%), or bronchopneumonia (3%) and all nine patients with DAD pattern were included in the severe group. Uivariate and multivariate analyses showed an elevated procalcitonin (odds ratio [OR], 2.521; 95% confidence interval [CI], 1.001–6.303, P = 0.048), and higher visual CT scores (OR, 1.137; 95% CI, 1.042–1.236; P = 0.003) or higher total extent by AI measurement (OR, 1.048; 95% CI, 1.020–1.076; P < 0.001) were significantly associated with a severe clinical course. @*Conclusion@#CT findings of COVID-19 pneumonia can be classified into OP, DAD, or bronchopneumonia patterns and all patients with DAD pattern were included in severe group. Elevated inflammatory markers and higher CT scores were found to be significant predictors of poor prognosis in patients with COVID-19 pneumonia.

Inflammatory Endobronchial Myofibroblastic Tumor: A Case Report

Inflammatory myofibroblastic tumor is a rare benign lesion that accounts for 0.04–1% of all lung tumors and usually appears as a solitary pulmonary nodule or mass. Here, we report the case of an endobronchial inflammatory myofibroblastic tumor in a 21-year-old man with a focus on the imaging findings and a review of previous literature.

A Rare Case of Tracheal Leiomyoma: Role of Digital Tomosynthesis in Diagnosis and Treatment

Tracheal leiomyoma is a rare benign tumor, which is composed of transformed cells of mesenchymal origin. We describe a case in which digital tomosynthesis was useful to evaluate a tracheal tumor that was overlooked on initial chest radiographs.

Establishment of a Nationwide Korean Imaging Cohort of Coronavirus Disease 2019

Background@#The Korean Society of Thoracic Radiology (KSTR) recently constructed a nation-wide coronavirus disease 2019 (COVID-19) database and imaging repository, referred to the Korean imaging cohort of COVID-19 (KICC-19) based on the collaborative efforts of its members. The purpose of this study was to provide a summary of the clinico-epidemiological data and imaging data of the KICC-19. @*Methods@#The KSTR members at 17 COVID-19 referral centers retrospectively collected imaging data and clinical information of consecutive patients with reverse transcription polymerase chain reaction-proven COVID-19 in respiratory specimens from February 2020 through May 2020 who underwent diagnostic chest computed tomography (CT) or radiograph in each participating hospital. @*Results@#The cohort consisted of 239 men and 283 women (mean age, 52.3 years; age range, 11–97 years). Of the 522 subjects, 201 (38.5%) had an underlying disease. The most common symptoms were fever (n = 292) and cough (n = 245). The 151 patients (28.9%) had lymphocytopenia, 86 had (16.5%) thrombocytopenia, and 227 patients (43.5%) had an elevated CRP at admission. The 121 (23.4%) needed nasal oxygen therapy or mechanical ventilation (n = 38; 7.3%), and 49 patients (9.4%) were admitted to an intensive care unit.Although most patients had cured, 21 patients (4.0%) died. The 465 (89.1%) subjects underwent a low to standard-dose chest CT scan at least once during hospitalization, resulting in a total of 658 CT scans. The 497 subjects (95.2%) underwent chest radiography at least once during hospitalization, which resulted in a total of 1,475 chest radiographs. @*Conclusion@#The KICC-19 was successfully established and comprised of 658 CT scans and 1,475 chest radiographs of 522 hospitalized Korean COVID-19 patients. The KICC-19 will provide a more comprehensive understanding of the clinical, epidemiological, and radiologic characteristics of patients with COVID-19.

Influence of Heart Rate and Innovative Motion-Correction Algorithm on Coronary Artery Image Quality and Measurement Accuracy Using 256-Detector Row Computed Tomography Scanner: Phantom Study

OBJECTIVE: To investigate the efficacy of motion-correction algorithm (MCA) in improving coronary artery image quality and measurement accuracy using an anthropomorphic dynamic heart phantom and 256-detector row computed tomography (CT) scanner. MATERIALS AND METHODS: An anthropomorphic dynamic heart phantom was scanned under a static condition and under heart rate (HR) simulation of 50–120 beats per minute (bpm), and the obtained images were reconstructed using conventional algorithm (CA) and MCA. We compared the subjective image quality of coronary arteries using a four-point scale (1, excellent; 2, good; 3, fair; 4, poor) and measurement accuracy using measurement errors of the minimal luminal diameter (MLD) and minimal luminal area (MLA). RESULTS: Compared with CA, MCA significantly improved the subjective image quality at HRs of 110 bpm (1.3 ± 0.3 vs. 1.9 ± 0.8, p = 0.003) and 120 bpm (1.7 ± 0.7 vs. 2.3 ± 0.6, p = 0.006). The measurement error of MLD significantly decreased on using MCA at 110 bpm (11.7 ± 5.9% vs. 18.4 ± 9.4%, p = 0.013) and 120 bpm (10.0 ± 7.3% vs. 25.0 ± 16.5%, p = 0.013). The measurement error of the MLA was also reduced using MCA at 110 bpm (19.2 ± 28.1% vs. 26.4 ± 21.6%, p = 0.028) and 120 bpm (17.9 ± 17.7% vs. 34.8 ± 19.6%, p = 0.018). CONCLUSION: Motion-correction algorithm can improve the coronary artery image quality and measurement accuracy at a high HR using an anthropomorphic dynamic heart phantom and 256-detector row CT scanner.

Study of the Efficacy of PET/CT in Lung Aspiration Biopsy and Factors Associated with False-Negative Results

PURPOSE@#We compared the outcomes of percutaneous transthoracic needle aspiration biopsy (PCNA) of lung masses in cases with and without prior positron emission tomography/computed tomography (PET/CT) information, and investigated the factors associated with false-negative pathological results.@*MATERIALS AND METHODS@#From a total of 291 patients, 161 underwent PCNA without prior PET/CT imaging, while 130 underwent PET/CT before PCNA. Clinical characteristics, procedural variables, pathological results, and diagnostic success rates were compared between the 2 groups. Among patients with initial negative (non-specific benign) PCNA results, the radiological findings of these groups were compared to evaluate the predictors of false-negative lesions.@*RESULTS@#No significant difference was found in the clinical characteristics, procedural characteristics, and pathological results of the 2 groups, nor was the diagnostic rate significantly different between them (p = 0.818). Among patients with initial negative PCNA results, radiological characteristics were similar in both the groups. In multivariate analysis, the presence of necrosis (p = 0.005) and ground-glass opacity (GGO) (p = 0.011) were the significant characteristics that indicated an increased probability of initial false-negative results in PCNA.@*CONCLUSION@#Routine PET/CT did not have any additional benefit in patients undergoing PCNA of lung masses. The presence of necrosis or GGO could indicate an increased probability of false-negative pathological results.

Cystic Neck Mass in an Adult: Unusual Manifestation of a Mediastinal Mature Teratoma

Anterior mediastinal teratomas are congenital tumors containing derivatives of all three germ layers. They usually grow slowly and are often detected incidentally by imaging studies. We describe the case of a 38-year-old man with an anterior mediastinal teratoma extending to the anterior neck, which resulted in a cystic neck mass.

Predictive Value of Cardiac Magnetic Resonance Imaging-Derived Myocardial Strain for Poor Outcomes in Patients with Acute Myocarditis

OBJECTIVE: To evaluate the utility of cardiovascular magnetic resonance (CMR)-derived myocardial strain measurement for the prediction of poor outcomes in patients with acute myocarditis. MATERIALS AND METHODS: We retrospectively analyzed data from 37 patients with acute myocarditis who underwent CMR. Left ventricular (LV) size, LV mass index, ejection fraction and presence of myocardial late gadolinium enhancement (LGE) were analyzed. LV circumferential strain (Ecc(SAX)), radial strain (Err(SAX)) from mid-ventricular level short-axis cine views and LV longitudinal strain (Ell(LV)), radial strain (Err(Lax)) measurements from 2-chamber long-axis views were obtained. In total, 31 of 37 patients (83.8%) underwent follow-up echocardiography. The primary outcome was major adverse cardiovascular event (MACE). Incomplete LV functional recovery was a secondary outcome. RESULTS: During an average follow-up of 41 months, 11 of 37 patients (29.7%) experienced MACE. Multivariable Cox proportional hazard regression analysis, which included LV mass index, LV ejection fraction, the presence of LGE, Ecc(SAX), Err(SAX), Ell(LV), and Err(Lax) values, indicated that the presence of LGE (hazard ratio, 42.88; p = 0.014), together with ErrLax (hazard ratio, 0.77 per 1%, p = 0.004), was a significant predictor of MACE. Kaplan-Meier analysis demonstrated worse outcomes in patient with LGE and an Err(Lax) value ≤ 9.48%. Multivariable backward regression analysis revealed that Err(Lax) values were the only significant predictors of LV functional recovery (hazard ratio, 0.54 per 1%; p = 0.042). CONCLUSION: CMR-derived Err(Lax) values can predict poor outcomes, both MACE and incomplete LV functional recovery, in patients with acute myocarditis, while LGE is only a predictor of MACE.

Ankle Arthrodesis Outcomes in Ankle Osteoarthritis: Comparison between Anterior Approach and Transfibular Approach / 대한족부족관절학회지

PURPOSE: The purpose of this study was to compare the clinical and radiologic results of arthrodesis between anterior approach and transfibular approach arthrodesis in ankle arthritis. MATERIALS AND METHODS: There were 61 cases of ankle arthritis treated by anterior or transfibular ankle arthrodesis in our hospital from April 2008 to March 2012. We investigated 29 cases (27 patients) who underwent ankle arthrodesis with an anterior approach (15 cases) and transfibular approach (14 cases), and were followed for over two years. Clinically, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, pain visual analogue scale (VAS), and subjective satisfaction degrees were evaluated. In addition, ankle coronal and sagittal alignments were evaluated using plain radiographs at 6 and 24 months, postoperatively. RESULTS: Clinically, preoperative mean AOFAS score and VAS was 41.3 and 6.4, and were changed to 58.9 and 3.3 postoperatively in the anterior approach group. In the transfibular approach group, preoperative mean AOFAS score was 36.6 and VAS was 7.1, and they were changed to 54.9 and 3.4 postoperatively. However, no significant differences in the clinical results were observed between the two groups (p=0.297). Duration of attaining union was 8.1 weeks in the anterior approach group and 10.4 weeks in the transfibular approach group. Complications were delayed union in one case, nonunion in three cases, cancellous screw breakage in three cases, and complex regional reflex syndrome in one case. CONCLUSION: After transfibular ankle arthrodesis as treatment of ankle osteoarthritis, the tendency for valgus angulation of the ankle at the final follow-up was observed and 6.5 mm cancellous screw breakage occurred frequently. Therefore, in order to achieve better stability, it is necessary to use 6.5 mm cannulated screws rather than 6.5 mm cancellous screws for ankle arthrodesis.

Isolated Left Ventricular Apical Hypoplasia with Infundibular Pulmonary and Aortic Stenosis: a Rare Combination

Isolated left ventricular (LV) apical hypoplasia is a rare congenital cardiac anomaly which is not accompanied by other cardiac abnormalities, with the exception of two cases. We report a case of a 33-year-old male patient with isolated LV apical hypoplasia combined with infundibular pulmonary stenosis and aortic stenosis. We review a literature focusing on the characteristic magnetic resonance features and combined cardiac abnormalities.

One-stage Laparoscopic Repair of Morgagni and Inguinal Hernias in a Two-month Old Male

The development of Morgagni hernias is related to malformations of the embryologic septum transversum after failure of the sternal and costal fibrotendinous elements of the diaphragm to fuse. The overall incidence of Morgagni hernias among all congenital diaphragmatic defects is 3% to 4%. Inguinal hernias are the most common hernias in males and females (25% and 2%, respectively). An inguinal hernia is defined as a protrusion of the abdominal cavity contents through the inguinal canal. The combination of Morgagni and inguinal hernias is rare, and treatment using laparoscopic surgery has not been previously reported. This case presents a one-stage laparoscopic repair of Morgagni and inguinal hernias in a 2-month-old male.

A Pulmonary Paragonimiasis Case Mimicking Metastatic Pulmonary Tumor

Pulmonary paragonimiasis is a relatively rare cause of lung disease revealing a wide variety of radiologic findings, such as air-space consolidation, nodules, and cysts. We describe here a case of pulmonary paragonimiasis in a 27-year-old woman who presented with a 2-month history of cough and sputum. Based on chest computed tomography (CT) scans and fluorodeoxyglucose positron emission tomography (FDG-PET) findings, the patient was suspected to have a metastatic lung tumor. However, she was diagnosed as having Paragonimus westermani infection by an immunoserological examination using ELISA. Follow-up chest X-ray and CT scans after chemotherapy with praziquantel showed an obvious improvement. There have been several reported cases of pulmonary paragonimiasis mimicking lung tumors on FDG-PET. However, all of them were suspected as primary lung tumors. To our knowledge, this patient represents the first case of paragonimiasis mimicking metastatic lung disease on FDG-PET CT imaging.

Outcome of Pandemic H1N1 Pneumonia: Clinical and Radiological Findings for Severity Assessment

BACKGROUND/AIMS: Pandemic influenza A (H1N1) virus infection presents with variable severity. However, little is known about clinical predictors of disease severity. We studied the clinical predictors of severe pandemic H1N1 pneumonia and their correlation with radiological findings. METHODS: We reviewed medical and radiological records of adults with pandemic H1N1 pneumonia. After classification of patients into severe and non-severe groups, the following data were evaluated: demographic data, pneumonia severity index (PSI), CURB65, risk factors, time to first dose of antiviral medication, routine laboratory data, clinical outcome, and radiological characteristics. RESULTS: Of 37 patients with pandemic H1N1 pneumonia, 12 and 25 were assigned to the severe and non-severe groups, respectively. PSI score, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dyhydrogenase (LDH) levels were higher in the severe group than in the non-severe group (p = 0.035, 0.0003, 0.0023, and 0.0002, respectively). AST, ALT, and LDH levels were positively correlated with the radiological findings (p < 0.0001, 0.0003, and < 0.0001, respectively) and with the number of involved lobes (p = 0.663, 0.0134, and 0.0019, respectively). The most common finding on high resolution computed tomography (HRCT) scans was ground-glass attenuation with consolidation (n = 22, 60%), which had a predominantly patchy distribution (n = 31). CONCLUSIONS: We demonstrated a positive correlation between clinical findings, such as serum AST, ALT, and LDH levels, and radiological findings. A combination of clinical and HRCT indicators would be useful in predicting the clinical outcome of pandemic H1N1 pneumonia.

Chest Radiographic Findings in Primary Pulmonary Tuberculosis: Observations from High School Outbreaks

OBJECTIVE: To describe the radiographic findings of primary pulmonary tuberculosis (TB) in previously healthy adolescent patients. MATERIALS AND METHODS: The Institutional Review Board approved this retrospective study, with a waiver of informed consent from the patients. TB outbreaks occurred in 15 senior high schools and chest radiographs from 58 students with identical strains of TB were analyzed by restriction fragment length polymorphism analysis by two independent observers. Lesions of nodule(s), consolidation, or cavitation in the upper lung zones were classified as typical TB. Mediastinal lymph node enlargement; lesions of nodule(s), consolidation, or cavitation in lower lung zones; or pleural effusion were classified as atypical TB. Inter-observer agreement for the presence of each radiographic finding was examined by kappa statistics. RESULTS: Of 58 patients, three (5%) had normal chest radiographs. Cavitary lesions were present in 25 (45%) of 55 students. Lesions with upper lung zone predominance were observed in 27 (49%) patients, whereas lower lung zone predominance was noted in 18 (33%) patients. The remaining 10 (18%) patients had lesions in both upper and lower lung zones. Pleural effusion was not observed in any patient, nor was the mediastinal lymph node enlargement. Hilar lymph node enlargement was seen in only one (2%) patient. Overall, 37 (67%) students had the typical form of TB, whereas 18 (33%) had TB lesions of the atypical form. CONCLUSION: The most common radiographic findings in primary pulmonary TB by recent infection in previously healthy adolescents are upper lung lesions, which were thought to be radiographic findings of reactivation pulmonary TB by remote infection.

Two Cases of Benign Solitary Schwannoma with Pleural Effusion / 결핵및호흡기질환

Schwannoma represents approximately 40% of neurogenic tumors arising in the mediastinum, and develops along the sympathetic or parasympathetic chain, intercostals nerve, and spinal ganglia. It is usually asymptomatic, and is confronted accidentally but can produce chest pain, cough and dyspnea. However, dyspnea with pleural effusion is rare in patients with benign schwannoma. We encountered two cases of benign schwannoma with pleural effusion. Both cases had similar initial symptoms and the characteristics of a mass but the characteristics of pleural effusion analysis were different. The benign schwannoma was confirmed in two cases using VATS (video-assisted tharawswpic surgery).

Primary Alveolar Soft Part Sarcoma of the Lung

Alveolar soft part sarcoma (ASPS) is a rare epithelial-like soft tissue sarcoma. The two main sites of its occurrence are the lower extremities in adults and the head and neck in children. Primary pulmonary involvement of this sarcoma, without evidence of soft tissue tumor elsewhere, is very exceptional. We present a case of primary ASPS of the lung in a 42-yr-old woman. A computed tomographic scan of the thorax demonstrated a well-circumscribed, solid tumor located in the right upper lobe. The mass was resected by right upper lobectomy. After 5 months, three metastatic lesions, involving lumbar vertebrae and occipital scalp, were found. Histologically, the tumor consisted of alveolar nests of large polygonal tumor cells, the cytoplasm of which frequently revealed periodic acid-Schiff-positive, diastase-resistant intracytoplasmic rod-like structures. On immunohistochemical staining, the tumor cells were positive only for vimentin and alpha-smooth muscle actin. Ultrastuctural study using electron microscopy revealed characteristic electron-dense, rhomboid intracytoplasmic crystals.