The spectrum of eosinophilic lung disease: radiologic findings

Uncommon Causes of Interlobular Septal Thickening on CT Images and Their Distinguishing Features

Interlobular septa thickening (ILST) is a common and easily recognized feature on computed tomography (CT) images in many lung disorders. ILST thickening can be smooth (most common), nodular, or irregular. Smooth ILST can be seen in pulmonary edema, pulmonary alveolar proteinosis, and lymphangitic spread of tumors. Nodular ILST can be seen in the lymphangitic spread of tumors, sarcoidosis, and silicosis. Irregular ILST is a finding suggestive of interstitial fibrosis, which is a common finding in fibrotic lung diseases, including sarcoidosis and usual interstitial pneumonia. Pulmonary edema and lymphangitic spread of tumors are the commonly encountered causes of ILST. It is important to narrow down the differential diagnosis as much as possible by assessing the appearance and distribution of ILST, as well as other pulmonary and extrapulmonary findings. This review will focus on the CT characterization of the secondary pulmonary lobule and ILST. Various uncommon causes of ILST will be discussed, including infections, interstitial pneumonia, depositional/infiltrative conditions, inhalational disorders, malignancies, congenital/inherited conditions, and iatrogenic causes. Awareness of the imaging appearance and various causes of ILST allows for a systematic approach, which is important for a timely diagnosis. This study highlights the importance of a structured approach to CT scan analysis that considers ILST characteristics, associated findings, and differential diagnostic considerations to facilitate accurate diagnoses.

FDG avid solitary pulmonary nodule mimicking lung cancer

A healthy 49-year-old nonsmoker lady, who was found to have an incidental finding of a lung lesion on a chest X-ray. A Chest CT scan was performed and revealed left upper lobe, 1.5 cm solitary nodule with ground glass borders that highly suspicious for Bronchioloalveolar carcinoma and warranted further investigation to rule out malignancy. The FDG PET and/or CT scan was performed for staging and further evaluation and it displayed avidity of the nodule with a standardized uptake value (SUV) of 6.2, no abnormal uptake elsewhere in the body. CT guided biopsy was arranged and the histopathology result revealed eosinophilic pneumonia.

Chest CT Diagnosis and Clinical Management of Drug-related Pneumonitis in Patients Receiving Molecular Targeting Agents and Immune Checkpoint Inhibitors: A Position Paper from the Fleischner Society

Use of molecular targeting agents and immune checkpoint inhibitors (ICIs) has increased the frequency and broadened the spectrum of lung toxicity, particularly in patients with cancer. The diagnosis of drug-related pneumonitis (DRP) is usually achieved by excluding other potential known causes. Awareness of the incidence and risk factors for DRP is becoming increasingly important. The severity of symptoms associated with DRP may range from mild or none to life-threatening with rapid progression to death. Imaging features of DRP should be assessed in consideration of the distribution of lung parenchymal abnormalities (radiologic pattern approach). The CT patterns reflect acute (diffuse alveolar damage) interstitial pneumonia and transient (simple pulmonary eosinophilia) lung abnormality, subacute interstitial disease (organizing pneumonia and hypersensitivity pneumonitis), and chronic interstitial disease (nonspecific interstitial pneumonia). A single drug can be associated with multiple radiologic patterns. Treatment of a patient suspected of having DRP generally consists of drug discontinuation, immunosuppressive therapy, or both, along with supportive measures eventually including supplemental oxygen and intensive care. In this position paper, the authors provide diagnostic criteria and management recommendations for DRP that should be of interest to radiologists, clinicians, clinical trialists, and trial sponsors, among others. This article is a simultaneous joint publication in Radiology and CHEST. The articles are identical except for stylistic changes in keeping with each journal's style. Either version may be used in citing this article. Published under a CC BY 4.0 license. Online supplemental material is available for this article.

Chest CT Diagnosis and Clinical Management of Drug-Related Pneumonitis in Patients Receiving Molecular Targeting Agents and Immune Checkpoint Inhibitors: A Position Paper From the Fleischner Society

Use of molecular targeting agents and immune checkpoint inhibitors (ICIs) has increased the frequency and broadened the spectrum of lung toxicity, particularly in patients with cancer. The diagnosis of drug-related pneumonitis (DRP) is usually achieved by excluding other potential known causes. Awareness of the incidence and risk factors for DRP is becoming increasingly important. The severity of symptoms associated with DRP may range from mild or none to life-threatening with rapid progression to death. Imaging features of DRP should be assessed in consideration of the distribution of lung parenchymal abnormalities (radiologic pattern approach). The CT patterns reflect acute (diffuse alveolar damage) interstitial pneumonia and transient (simple pulmonary eosinophilia) lung abnormality, subacute interstitial disease (organizing pneumonia and hypersensitivity pneumonitis), and chronic interstitial disease (nonspecific interstitial pneumonia). A single drug can be associated with multiple radiologic patterns. Treatment of a patient suspected of having DRP generally consists of drug discontinuation, immunosuppressive therapy, or both, along with supportive measures eventually including supplemental oxygen and intensive care. In this position paper, the authors provide diagnostic criteria and management recommendations for DRP that should be of interest to radiologists, clinicians, clinical trialists, and trial sponsors, among others.

Tamoxifen-induced acute eosinophilic pneumonia in a breast cancer patient

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If a patient who is taking tamoxifen coughs, be aware of the possibility of pneumonia caused by Tamoxifen.

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Tamoxifen is one of the cause of drug-induced lung injury.

Introduction

Tamoxifen is often used as antihormonal therapy in patients with breast cancer. However, it has various side effects, of which pneumonia is a rare occurrence.

Presentation of case

A 46-year-old female patient with breast cancer underwent surgical treatment. Tamoxifen was administered as adjuvant therapy on post-operative day 14; 2 days after administration of tamoxifen, the patient developed high fever of more than 39 °C and cough with dyspnea. Based on chest computed tomography findings of ground glass opacity, interlobular septal thickening, and mild pleural effusion in both lungs, eosinophilic pneumonia was suspected. Tamoxifen was discontinued and methylprednisolone injection was administered; the patient showed improvement of symptoms and radiographic findings.

Discussion

Tamoxifen was suspected as the cause of eosinophilic pneumonia since the patient developed high-grade fever at the time of tamoxifen administration, which subsided after discontinuation of the treatment. Other factors considered as the cause of pneumonia were examined, but all showed negative results. In order to confirm tamoxifen as the cause of pneumonia, tamoxifen treatment was restarted at follow-up (post-operative day 47); however, after 1 month, regular administration was not possible due to the development of itching symptom and difficulty in obtaining the patient’s cooperation.

Conclusion

The study highlights that if the patient on tamoxifen develops high fever and cough with dyspnea at 2–3days after the first administration, tamoxifen-induced pneumonia should be suspected.

Cardiopulmonary and Gastrointestinal Manifestations of Eosinophil- associated Diseases and Idiopathic Hypereosinophilic Syndromes: Multimodality Imaging Approach

Eosinophil-associated diseases (EADs) are a diverse group of disorders characterized by an increase in circulating or tissue eosinophils. Cardiopulmonary and gastrointestinal system involvement can be due to primary EAD with no known cause or can be secondary to known systemic disease. The cardiopulmonary spectrum of EADs comprises simple pulmonary eosinophilia, acute eosinophilic pneumonia, chronic eosinophilic pneumonia, Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis, bronchocentric granulomatosis, parasitic infections, and idiopathic hypereosinophilic syndrome. Eosinophilic gastrointestinal disorders include eosinophilic esophagitis, eosinophilic gastroenteritis, and eosinophilic colitis. Diagnosis is often challenging and requires a combination of clinical and imaging features along with laboratory findings. The absolute eosinophil count in peripheral blood and the percentage of eosinophils in bronchoalveolar lavage fluid are crucial in evaluation of various eosinophilic lung diseases. Although chest radiography is the initial imaging modality used in suspected cases of pulmonary EAD, multidetector computed tomography may demonstrate more characteristic pulmonary patterns, nodules, and subtle parenchymal abnormalities. Barium esophagography is used to assess mucosal abnormalities and the length and diameter of esophageal strictures. Magnetic resonance imaging is superior in providing valuable information in select patients, especially in evaluation of cardiac and gastrointestinal system involvement. Many patients require a multimodality imaging approach to enable diagnosis, guide treatment, and assess treatment response. Knowledge of the clinical features and imaging findings of the spectrum of EADs involving the lungs, heart, and gastrointestinal tract permits optimal patient care.

Simple pulmonary eosinophilia found on follow-up computed tomography of oncologic patients

OBJECTIVES

To investigate the prevalence of simple pulmonary eosinophilia (SPE) and validate CT findings of SPE found on follow-up CT of oncologic patients.

METHODS

We retrospectively reviewed 6977 cases of oncologic patients who underwent chest CT. A total of 66 individuals who met criteria for having SPE were identified. CT scans were fully re-assessed by consensus of 2 radiologists in terms of characteristics of pulmonary lesions.

RESULTS

The prevalence of SPE was 0.95%. A total of 193 lesions were identified and most of the lesions showed part-solid pattern (69.9%), round to ovoid contour (46.1%), ill-defined margin (90.2%), or partial halo appearance (74.8%). In addition, almost half of the lesions showed the vascular contact (49%). SPE appeared as either solitary (42.4%) or multiple lesions (57.6%). The majority of lesions were located in the periphery (76.2%), and lower lung zonal (67.4%) predominance was found.

CONCLUSIONS

The frequency of SPE in oncologic patients with CT findings of GGO, part-solid lesion was high (17.5%). Therefore, when key features of CT findings suggesting SPE (part-solid nodule; ill-defined margin; peripheral distribution; and lower lung zone predominance) are newly discovered on follow-up chest CT in oncologic patients, it would be useful to correlate with blood test and do short-term follow-up in order to avoid unnecessary invasive procedure.

Consolidation

Consolidation refers to an area of homogeneous increase in lung parenchymal attenuation that obscures the margins of vessels and airway walls [1]. Air bronchograms may be present with consolidative area. Pathologically, consolidation represents an exudate or other product of disease that replaces alveolar air, rendering the lung solid [2, 3].

Pulmonary schistosomiasis - imaging features

Schistosomiasis is a helminthic infection that is endemic in tropical and subtropical regions. Pulmonary involvement can be divided into two categories: acute or chronic compromise. Chronic and recurrent infection develops in persons living or travelling in endemic areas. In the lungs, granuloma formation and fibrosis around the schistosome eggs retained in the pulmonary vasculature may result in obliterative arteriolitis and pulmonary hypertension leading to cor pulmonale. Acute schistosomiasis is associated with primary exposure and is commonly seen in nonimmune travelers. The common CT findings in acute pulmonary schistosomiasis are small pulmonary nodules ranging from 2 to 15 mm and larger nodules with ground glass-opacity halo. Katayama fever is a severe clinical manifestation of acute involvement. We present a case of pulmonary involvement in schistosomiasis and provide a discussion about typical imaging findings in the acute and chronic form.

Imaging of pulmonary vasculitis

The presence of pulmonary vasculitis can be suggested by a clinical presentation that includes diffuse pulmonary hemorrhage, acute glomerulonephritis, chronic refractory sinusitis or rhinorrhea, imaging findings of nodules or cavities, mononeuritis multiplex, multisystemic disease, and palpable purpura. Serologic tests, including the use of cytoplasmic antineutrophil cytoplasmic antibody (ANCA) and perinuclear ANCA, are performed for the differential diagnosis of the diseases. A positive cytoplasmic ANCA test result is specific enough to make a diagnosis of ANCA-associated granulomatous vasculitis if the clinical features are typical. Perinuclear ANCA positivity raises the possibility of Churg-Strauss syndrome or microscopic polyangiitis. Imaging findings of pulmonary vasculitis are diverse and often poorly specific. The use of a pattern-based approach to the imaging findings may help narrow the differential diagnosis of various pulmonary vasculitides. Integration of clinical, laboratory, and imaging findings is mandatory for making a reasonably specific diagnosis.

Eosinophilic lung diseases: a clinical, radiologic, and pathologic overview

Eosinophilic lung diseases are a diverse group of pulmonary disorders associated with peripheral or tissue eosinophilia. They are classified as eosinophilic lung diseases of unknown cause (simple pulmonary eosinophilia [SPE], acute eosinophilic pneumonia [AEP], chronic eosinophilic pneumonia [CEP], idiopathic hypereosinophilic syndrome [IHS]), eosinophilic lung diseases of known cause (allergic bronchopulmonary aspergillosis [ABPA], bronchocentric granulomatosis [BG], parasitic infections, drug reactions), and eosinophilic vasculitis (allergic angiitis, granulomatosis [Churg-Strauss syndrome]). The percentages of eosinophils in peripheral blood and bronchoalveolar lavage fluid are essential parts of the evaluation. Chest computed tomography (CT) demonstrates a more characteristic pattern and distribution of parenchymal opacities than does conventional chest radiography. At CT, SPE and IHS are characterized by single or multiple nodules with a surrounding ground-glass-opacity halo, AEP mimics radiologically hydrostatic pulmonary edema, and CEP is characterized by nonsegmental airspace consolidations with peripheral predominance. ABPA manifests with bilateral central bronchiectasis with or without mucoid impaction. The CT manifestations of BG are nonspecific and consist of a focal mass or lobar consolidation with atelectasis. The most common CT findings in Churg-Strauss syndrome include sub-pleural consolidation with lobular distribution, centrilobular nodules, bronchial wall thickening, and interlobular septal thickening. The integration of clinical, radiologic, and pathologic findings facilitates the initial and differential diagnoses of various eosinophilic lung diseases.

Pulmonary Computed Tomography Findings of Visceral Larva Migrans Caused by Ascaris suum

OBJECTIVE

To retrospectively evaluate the computed tomography (CT) findings of pulmonary involvement in patients with visceral larva migrans caused by Ascaris suum.

METHODS

Institutional review board approval was obtained, and informed consent was waived. Chest CT scans obtained between January 1994 and November 2005 in 32 patients infected with A. suum were retrospectively evaluated by 3 chest radiologists. In 4 patients who underwent surgical or transbronchial biopsy, comparisons of the CT images with the actual specimens were performed.

RESULTS

On CT scans, abnormal findings were seen in 28 patients. The most common abnormality consisted of nodules (n = 19) in which the majority had a halo of ground-glass attenuation (n = 17), followed by ground-glass attenuation (n = 18), and interlobular septal thickening (n = 14). These abnormalities were predominantly seen in the peripheral lung (n = 25). Of the 7 patients who underwent follow-up CT scans, nodules (n = 6) and ground-glass attenuation (n = 5) had migrated in 4 patients. Pathologically, these findings corresponded to marked eosinophilic infiltration into the interstitium.

CONCLUSIONS

These CT findings are considered to be suggestive of thoracic involvement in patients with visceral larva migrans caused by A. suum.

Drug-induced lung diseases: most common reaction patterns and corresponding high-resolution CT manifestations

Drug-induced lung disease is an increasingly common cause of morbidity and mortality. The diagnosis is based on clinical history and consistent radiologic findings. Lung biopsy is performed in a small percentage of cases. High-resolution CT may demonstrate parenchymal abnormalities in patients with normal radiographs and provides a better depiction of the pattern and distribution of findings. Knowledge of the most common high-resolution CT manifestations and the corresponding histologic patterns is important for early recognition and proper management of drug-induced lung disease.

Simple pulmonary eosinophilia evaluated by means of FDG PET: the findings of 14 cases

Objective

We wanted to describe the findings of simple pulmonary eosinophilia with using 18 fluorodeoxyglucose (FDG) positron emission tomography (PET).

Materials and Methods

We analysed the findings of 14 patients who underwent thoracic computed tomography (CT) and PET, and then they were subsequently proven to have simple pulmonary eosinophilia. PET studies were performed in four patients with malignancy to evaluate for cancer metastasis, and PET scans were also done in 10 healthy subjects who underwent volunteer cancer screening. The PET scans were evaluated by using the maximum standardized uptake values (SUVs). The subjects' CT findings also were reviewed and correlated with the PET findings.

Results

A total of 42 nodules were detected on the CT scans. There were single nodules in three patients and multiple nodules in 11 patients (mean number of nodules: 3, range: 1-10, mean diameter: 9.5 mm ± 4.7). Twelve of 42 (28.6%) nodules showed FDG uptake and their mean maximum SUV was 2.5 ± 1.6 (range: 0.6-5.3). Five of six solid nodules showed FDG uptake (2.2 ± 1.1, range: 0.9-3.6), six of 11 semisolid nodules showed FDG uptake (3.1 ± 1.8, range: 0.6-5.3) and one of 25 pure ground-glass opacity nodule showed a maximum SUV of 0.8. The maximum SUVs of seven nodules in five patients were greater than 2.5. The maximum SUVs were significantly different according to the nodule types (p < 0.001).

Conclusion

Simple pulmonary eosinophilia commonly causes an increase in FDG uptake. Therefore, correlation of the PET findings with the CT findings or the peripheral eosinophil counts can help physicians arrive at the correct diagnosis of simple pulmonary eosinophilia.

Drug-Induced Eosinophilic Pneumonia: High-Resolution CT Findings in 14 Patients

OBJECTIVE

The purpose of this study was to evaluate the high-resolution CT findings of drug-induced eosinophilic pneumonias.

CONCLUSION

Drug-induced eosinophilic pneumonias usually manifest as areas of consolidation and ground-glass opacity most commonly involving the outer third of the lungs.

The radiological spectrum of pulmonary aspergillosis

Imaging findings in the pulmonary aspergilloses can answer important clinical questions. Steroid-responsive chronic asthma due to allergic bronchopulmonary aspergillosis can be differentiated from simple asthma by computed tomography (CT) evidence of extensive and severe central bronchiectasis, mucoid impaction, or small airways lesions. The simple aspergilloma can be differentiated from the complex aspergilloma by the absence of: constitutional symptoms, para-cystic lung opacities, cyst expansion, or progressive pleural thickening. The CT halo sign is a transient finding that can provide a probable diagnosis of early invasive pulmonary aspergillosis in patients who are at extraordinarily high risk of the infection. Patients with a halo sign at baseline are more likely to have a satisfactory treatment response than those without this indicator.

Modern diagnosis and treatment of primary eosinophilia

The recent discovery of an eosinophilia-specific, imatinib-sensitive, karyotypically occult but fluorescence in situ hybridization-apparent molecular lesion in a subset of patients with blood eosinophilia has transformed the diagnostic as well as treatment approach to eosinophilic disorders. Primary (i.e. nonreactive) eosinophilia is considered either "clonal" or "idiopathic" based on the presence or absence, respectively, of either a molecular or bone marrow histological evidence for a myeloid neoplasm. Clonal eosinophilia might accompany a spectrum of clinicopathological entities, the minority of whom are molecularly characterized; Fip1-like-1-platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA(+)) systemic mastocytosis, platelet-derived growth factor receptor beta (PDGFRB)-rearranged atypical myeloproliferative disorder, chronic myeloid leukemia, and the 8p11 syndrome that is associated with fibroblast growth factor receptor 1 (FGFR1) rearrangement. Hypereosinophilic syndrome (HES) is a subcategory of idiopathic eosinophilia and is characterized by an absolute eosinophil count of > or =1.5 x 10(9)/l for at least 6 months as well as eosinophil-mediated tissue damage. At present, a working diagnosis of primary eosinophilia mandates a bone marrow examination, karyotype analysis, and additional molecular studies in order to provide the patient with accurate prognostic information as well as select appropriate therapy. For example, the presence of either PDGFRA or PDGFRB mutations warrants the use of imatinib in clonal eosinophilia. In HES, prednisone, hydroxyurea, and interferon-alpha constitute first-line therapy, whereas imatinib, cladribine, and monoclonal antibodies to either interleukin-5 (mepolizumab) or CD52 (alemtuzumab) are considered investigational. Allogeneic transplantation offers a viable treatment option for drug-refractory cases.

High-resolution CT of drug-induced lung disease

Drug-induced pulmonary toxicity is increasing and early diagnosis is important because of the associated morbidity and mortality. Diagnosis is often difficult and is usually based on a history of drug therapy and exclusion of infection, radiation pneumonitis, and recurrence of the underlying disease. Although HRCT findings are frequently nonspecific, diagnosis can be facilitated by an understanding of the most common histopathologic and radiologic manifestations of drug-induced lung injury and knowledge of the drugs usually involved.

Drug-induced lung injury

Lung injury is an increasing cause of morbidity and mortality in patients treated with cytotoxic and noncytotoxic drugs. Prompt diagnosis is important because early drug-induced lung injury will often regress with the cessation of therapy. Diagnosis requires a high index of suspicion because infection, radiation pneumonitis, and recurrence of the underlying disease can manifest clinically and radiologically in a similar manner. Because the lungs have only a limited number of histopathologic responses to injury, including pulmonary edema/diffuse alveolar damage, NSIP, BOOP, EP, and pulmonary hemorrhage, knowledge of these manifestations and the corresponding radiologic manifestations can often be useful in suggesting a diagnosis of drug-induced lung injury. An understanding of the drugs most commonly associated with lung injury can also facilitate diagnosis.

High-resolution CT of alveolar filling disorders

Airspace filling process is characterized on CT by the presence of one or more fairly homogeneous areas of consolidation with little or no volume loss. The consolidation may be segmental, subsegmental, lobular, or acinar (10 mm or less in diameter). Poorly defined centrilobular nodules may be associated. The margin of the consolidation usually is poorly defined except in the areas in which the consolidation abuts the pleura. Air-containing bronchi or bronchioles (CT air bronchograms or air bronchiolograms) are seen frequently. Many diseases can present with alveolar filling disorders. Because the HRCT findings overlap among various alveolar filling disorders, it may be impossible to make a definite diagnosis with HRCT findings alone. Integration of HRCT findings including disease pattern and distribution and time factors including evolution and resolution of the disease, however, may enable to narrow differential diagnosis of alveolar filling diseases. Furthermore, clinical and laboratory findings also may provide helpful clues to reach a reasonable diagnosis. The role of HRCT in alveolar filling disorders is not limited to diagnosis. HRCT also plays a useful role in determining the extent of disease and in identifying accompanying abnormalities, and complications of the primary disease.

Radiological-pathological correlation: alveolar pattern

This review summarizes important pathological lesions of the lung that typically present radiographically with an 'alveolar pattern'. For each entity, the latest findings as to its pathogenesis, aetiology and pathology are reviewed in the introductory remarks. We then present the typical radiological appearances alongside macroscopic and microscopic pathological photographs. It is hoped that the parallel presentation of radiological image with the pathology will enhance the understanding of the diverse range of diseases the aevolar pattern comprises.

Eosinophilic lung diseases: diagnostic accuracy of thin-section CT in 111 patients

PURPOSE

To determine whether various eosinophilic lung diseases can be differentiated by means of thin-section computed tomography (CT).

MATERIALS AND METHODS

Thin-section CT scans in 111 patients with eosinophilic lung diseases-40 with chronic eosinophilic pneumonia, 16 with Churg-Strauss syndrome, 16 with allergic bronchopulmonary aspergillosis (ABPA), 13 with acute eosinophilic pneumonia, 12 with simple pulmonary eosinophilia, 11 with drug-induced eosinophilic pneumonia, and three with hypereosinophilic syndrome-were assessed independently by two observers. The observers recorded the abnormalities, diagnosis, and degree of confidence in the diagnosis.

RESULTS

The two observers made a correct first-choice diagnosis on average in 61% of readings. The correct diagnosis was made in 78% of cases of chronic eosinophilic pneumonia; 81%, acute eosinophilic pneumonia; 44%, Churg-Strauss syndrome; 84%, ABPA; 17%, simple pulmonary eosinophilia; 27%, drug-induced eosinophilic pneumonia; and 33%, hypereosinophilic syndrome. The two observers made a correct diagnosis with a high degree of confidence in 36% of readings. There was moderate agreement between the observers for the correct diagnosis (kappa, 0.47) and for the correct diagnosis with a high degree of confidence (kappa, 0.59).

CONCLUSION

Although eosinophilic lung diseases often can be differentiated by means of thin-section CT, correlation between CT findings and careful clinical evaluation are required for a definitive diagnosis.

Acute parenchymal lung disease in immunocompetent patients: diagnostic accuracy of high-resolution CT

OBJECTIVE

The purpose of this study was to determine whether acute parenchymal lung diseases can be differentiated on the basis of the pattern and distribution of abnormalities revealed on high-resolution CT.

MATERIALS AND METHODS

High-resolution CT scans of 90 patients with acute parenchymal lung diseases (19 with bacterial pneumonia, 13 with mycoplasmal pneumonia, 21 with acute interstitial pneumonia, 18 with hypersensitivity pneumonitis, 10 with acute eosinophilic pneumonia, and nine with pulmonary hemorrhage) were independently assessed by two observers who had no knowledge of clinical or pathologic data. The observers recorded abnormalities, their first-choice diagnosis, and their degree of confidence in their first-choice diagnosis.

RESULTS

The two observers made a correct first-choice diagnosis in an average of 55 (61%) of 90 cases. Correct first-choice diagnosis was made in 50% of cases of bacterial pneumonia, 62% of mycoplasmal pneumonia, 90% of acute interstitial pneumonia, 72% of hypersensitivity pneumonitis, 30% of acute eosinophilic pneumonia, and 28% of pulmonary hemorrhage. CT findings allowed distinction between infectious and noninfectious causes in 81 (90%) of 90 cases.

CONCLUSION

High-resolution CT is helpful in the differential diagnosis of infectious from noninfectious acute parenchymal lung disease. However, high-resolution CT is of limited value in making a specific diagnosis.

Blood clots mimicking peripheral intrabronchial tumors in patients with hemoptysis: CT and bronchoscopic findings

We report radiographic and clinical findings in two cigarette-smoking patients presenting with hemoptysis. On CT, both patients had peripheral intrabronchial masses together with parenchymal opacities. Bronchoscopy revealed the intrabronchial masses to be blood clots and the parenchymal opacities to correspond to areas of parenchymal hemorrhage. Our cases are novel in that both bronchial and parenchymal sequelae of hemorrhage were simultaneously visualized by CT. Also, our findings suggest that bronchial blood clots should be included in the differential diagnosis of peripheral intrabronchial lesions, notably in patients presenting with hemoptysis.

"Crazy paving appearance" on high resolution CT in various diseases

PURPOSE

The purpose of this work was to demonstrate the variety of causes of crazy-paving appearance (CPA) on high resolution CT (HRCT).

METHOD

To identify cases exhibiting CPA (ground-glass opacity with superimposed interlobular septal thickening and intralobular interstitial thickening) on HRCT, we prospectively searched for them over a period of 29 months.

RESULTS

We identified 10 cases of CPA on HRCT, including 4 Pneumocystis carinii pneumonia, 1 alveolar proteinosis, 1 usual interstitial pneumonia, 1 pulmonary hemorrhage, 1 acute radiation pneumonitis, 1 adult respiratory distress syndrome, and 1 drug-induced pneumonitis.

CONCLUSION

CPA can result from a variety of diseases. When we encounter CPA on HRCT, clinical information is necessary for differentiation of these entities.

Halo sign on high resolution CT: findings in spectrum of pulmonary diseases with pathologic correlation

The halo sign in a pulmonary nodule refers to the condition in which soft tissue attenuation of a pulmonary nodule is surrounded by peripheral ground glass attenuation on high resolution CT. The halo sign can be caused by several pathologic processes: hemorrhagic pulmonary nodules, tumor cell infiltration, and nonhemorrhagic inflammatory lesions. Hemorrhagic pulmonary nodules may occur in infectious diseases including invasive pulmonary aspergillosis, mucormycosis, and candidiasis and noninfectious diseases including Wegener granulomatosis and primary and metastatic hemorrhagic tumors. Tumor cell infiltration in bronchioloalveolar carcinoma, pulmonary lymphoma, and pulmonary metastatic neoplasm may appear with the halo sign. Eosinophilic lung disease and organizing pneumonia are representative of inflammatory lesions showing the sign.