High-resolution CT of bronchioloalveolar carcinoma

Back to Basics - 'Must Know' Classical Signs in Thoracic Radiology

There are a few signs in radiology which are based on many common objects or patterns that we come across in our routine lives. The objective behind the association between such common objects and the corresponding pathologies is to make the reader understand and remember the disease process. These signs do not necessarily indicate a particular disease, but are usually suggestive of a group of similar pathologies which will facilitate in the narrowing down of the differential diagnosis. These signs can be seen in different imaging modalities like plain radiograph and computed tomography. In this essay, we describe 24 classical radiological signs used in chest imaging, which would be extremely helpful in routine clinical practice not only for radiologists but also for chest physicians and cardiothoracic surgeons.

Surgical treatment of early-stage non-small-cell lung cancer

Surgical resection remains the standard of care for functionally operable early-stage non-small-cell lung cancer (NSCLC) and resectable stage IIIA disease. The role of invasive staging and restaging techniques is currently being debated, but they provide the largest biopsy samples which allow for precise mediastinal staging. Different types of operative procedures are currently available to the thoracic surgeon, and some of these interventions can be performed by video-assisted thoracic surgery (VATS) with the same oncological results as those by open thoracotomy. The principal aim of surgical treatment for NSCLC is to obtain a complete resection which has been precisely defined by a working group of the International Association for the Study of Lung Cancer (IASLC). Intraoperative staging of lung cancer is of utmost importance to decide on the extent of resection according to the intraoperative tumour (T) and nodal (N) status. Systematic nodal dissection is generally advocated to evaluate the hilar and mediastinal lymph nodes which are subdivided into seven zones according to the most recent 7th tumour-node-metastasis (TNM) classification. Lymph-node involvement not only determines prognosis but also the administration of adjuvant therapy.

In 2011, a new multidisciplinary adenocarcinoma classification was published introducing the concepts of adenocarcinoma in situ and minimally invasive adenocarcinoma. This classification has profound surgical implications. The role of limited or sublobar resection, comprising anatomical segmentectomy and wide wedge resection, is reconsidered for early-stage lesions which are more frequently encountered with the recently introduced large screening programmes. Numerous retrospective non-randomised studies suggest that sublobar resection may be an acceptable surgical treatment for early lung cancers, also when performed by VATS.

More tailored, personalised therapy has recently been introduced. Quality-of-life parameters and surgical quality indicators become increasingly important to determine the short-term and long-term impact of a surgical procedure. International databases currently collect extensive surgical data, allowing more precise calculation of mortality and morbidity according to predefined risk factors. Centralisation of care has been shown to improve results. Evidence-based guidelines should be further developed to provide optimal staging and therapeutic algorithms.

Aerogenous metastases: a potential game changer in the diagnosis and management of primary lung adenocarcinoma

OBJECTIVE

The purposes of this article are to summarize the relevant literature on aerogenous metastasis, explain the putative pathogenetic mechanism of aerogenous spread, present the characteristic imaging and pathologic features, and review the importance of aerogenous spread to staging and clinical management.

CONCLUSION

Cumulative evidence suggests that aerogenous spread may exist and is underrecognized. Imaging features are helpful in differentiating possible aerogenous spread of tumor from hematogenous and lymphatic metastases and from synchronous primary tumors. The putative occurrence of intrapulmonary aerogenous metastasis of lung cancer has staging, management, and prognostic implications.

The lung adenocarcinoma guidelines: what to be considered by surgeons

In 2011 the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society (ERS), have proposed a new subclassification of lung adenocarcinomas. This new classification was founded on an evidence-based approach to a systematic review of 11,368 citations from the related literature. Validation has involved projects relating to histologic and cytologic analysis of small biopsy specimens, histologic subtyping, grading, and observer variation among expert pathologists. As enormous resources are being spent on trials involving molecular and therapeutic aspects of adenocarcinoma of the lung, the development of standardized criteria is of great importance and should help advance the field, increasing the impact of research, and improving patient care. This classification is needed to assist in determining patient therapy and predicting outcome. The 2011 IASLC/ATS/ERS adenocarcinoma classification can have an impact on TNM staging. It may help in comparing histologic characteristics of multiple lung adenocarcinomas to determine whether they are intrapulmonary metastases versus separate primaries. Use of comprehensive histologic subtyping along with other histologic characteristics has been shown to have good correlation with molecular analyses and clinical behavior. Also, it may be more meaningful clinically to measure tumor size in lung adenocarcinomas that have a lepidic component by using invasive size rather than total size to determine the size T factor.

Pathologic classification of adenocarcinoma of lung

Recently, the 1999/2004 World Health Organization (WHO) classification of adenocarcinoma became less useful from a clinical standpoint as most adenocarcinomas belonged to the mixed subtype and the term bronchioloalveolar carcinoma (BAC) gave rise to much confusion among clinicians. For these reasons a new adenocarcinoma classification was introduced in 2011 by a joint working group of the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS). This represents an international, multidisciplinary effort joining pathologists, molecular biologists, pulmonary physicians, thoracic oncologists, radiologists, and thoracic surgeons. Currently, a distinction is made between pre-invasive lesions, minimally invasive and invasive lesions. The confusing term BAC is not used anymore and new subcategories include adenocarcinoma in situ and minimally invasive adenocarcinoma. Several aspects of this classification are discussed with main emphasis on its correlation with imaging techniques and its impact on diagnosis, treatment and prognosis. On chest computed tomography (CT) a distinction is made between solid and subsolid nodules, the latter comprising ground glass opacities (GGO), and partly solid lesions. Several studies incorporating CT and positron emission tomographic (PET) data show a good imaging-pathologic correlation. With the implementation of screening programs early lung cancer has become a hotly debated topic and sublobar resection is currently reconsidered for early lesions without lymph node involvement. This new classification will also have an impact on the TNM classification. Thoracic surgeons will continue to play a major role in the application, evaluation and further refinement of this new adenocarcinoma classification.

Bilateral pneumothorax complicating cystic metastases of bronchial squamous cell carcinoma under erlotinib

Cystic lung metastases are a rare presentation in non-small cell lung cancer and occurs mainly in squamous cell carcinoma. We present the case of a 57-year-old woman with a lung squamous cell carcinoma and cystic lung metastases, who developed bilateral metachronous pneumothorax while being administered erlotinib in third-line treatment. The apparition of a pneumothorax under chemotherapy is most often the result of tumor necrosis and formation of bronchopleural fistula. However, very few cases have been reported under targeted therapies, and to our knowledge this is the first case under erlotinib. This complication is potentially life-threatening, especially due to the possibility of pneumothorax bilateralization.

Diagnostic workup of lung cancer

Lung cancer is the most frequent cause of mortality worldwide. According to recent estimates, 222,520 new cases of lung cancer (non-small cell and small cell combined) were diagnosed and 157,300 lung cancer-related deaths occurred in 2010 in the United States alone. The two major histologic types of lung cancer are small cell lung cancer and non-small cell lung cancer. The diagnosis and management of lung cancer requires a multidisciplinary approach.

International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma

INTRODUCTION

Adenocarcinoma is the most common histologic type of lung cancer. To address advances in oncology, molecular biology, pathology, radiology, and surgery of lung adenocarcinoma, an international multidisciplinary classification was sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification is needed to provide uniform terminology and diagnostic criteria, especially for bronchioloalveolar carcinoma (BAC), the overall approach to small nonresection cancer specimens, and for multidisciplinary strategic management of tissue for molecular and immunohistochemical studies.

METHODS

An international core panel of experts representing all three societies was formed with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. A systematic review was performed under the guidance of the American Thoracic Society Documents Development and Implementation Committee. The search strategy identified 11,368 citations of which 312 articles met specified eligibility criteria and were retrieved for full text review. A series of meetings were held to discuss the development of the new classification, to develop the recommendations, and to write the current document. Recommendations for key questions were graded by strength and quality of the evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

The classification addresses both resection specimens, and small biopsies and cytology. The terms BAC and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced such as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure lepidic growth (AIS) or predominant lepidic growth with ≤ 5 mm invasion (MIA) to define patients who, if they undergo complete resection, will have 100% or near 100% disease-specific survival, respectively. AIS and MIA are usually nonmucinous but rarely may be mucinous. Invasive adenocarcinomas are classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous BAC), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous BAC), colloid, fetal, and enteric adenocarcinoma. This classification provides guidance for small biopsies and cytology specimens, as approximately 70% of lung cancers are diagnosed in such samples. Non-small cell lung carcinomas (NSCLCs), in patients with advanced-stage disease, are to be classified into more specific types such as adenocarcinoma or squamous cell carcinoma, whenever possible for several reasons: (1) adenocarcinoma or NSCLC not otherwise specified should be tested for epidermal growth factor receptor (EGFR) mutations as the presence of these mutations is predictive of responsiveness to EGFR tyrosine kinase inhibitors, (2) adenocarcinoma histology is a strong predictor for improved outcome with pemetrexed therapy compared with squamous cell carcinoma, and (3) potential life-threatening hemorrhage may occur in patients with squamous cell carcinoma who receive bevacizumab. If the tumor cannot be classified based on light microscopy alone, special studies such as immunohistochemistry and/or mucin stains should be applied to classify the tumor further. Use of the term NSCLC not otherwise specified should be minimized.

CONCLUSIONS

This new classification strategy is based on a multidisciplinary approach to diagnosis of lung adenocarcinoma that incorporates clinical, molecular, radiologic, and surgical issues, but it is primarily based on histology. This classification is intended to support clinical practice, and research investigation and clinical trials. As EGFR mutation is a validated predictive marker for response and progression-free survival with EGFR tyrosine kinase inhibitors in advanced lung adenocarcinoma, we recommend that patients with advanced adenocarcinomas be tested for EGFR mutation. This has implications for strategic management of tissue, particularly for small biopsies and cytology samples, to maximize high-quality tissue available for molecular studies. Potential impact for tumor, node, and metastasis staging include adjustment of the size T factor according to only the invasive component (1) pathologically in invasive tumors with lepidic areas or (2) radiologically by measuring the solid component of part-solid nodules.

Detección y caracterización del nódulo pulmonar por tomografía computarizada multicorte

Pulmonary nodules are a common finding in routine chest studies. Although there are no pathognomic clinical or radiological signs that enable the exact nature of a pulmonary nodule to be determined, the clinical context and the appropriate characterization of the pulmonary nodule make it possible to reach the correct diagnosis in most cases. This article discusses the most important aspects involved in the use of multislice computed tomography in the noninvasive detection and characterization of pulmonary nodules.

Solitary pulmonary metastases from renal cell carcinoma: comparison of high-resolution CT with pathological findings

PURPOSE

The aim of this study was to examine the radiographic features of solitary pulmonary metastases from renal cell carcinoma by comparing high-resolution CT (HRCT) findings with histopathological observations.

MATERIALS AND METHODS

Three thoracic radiologists retrospectively reviewed HRCT findings from eight patients who underwent surgery on the basis of the diagnosis of solitary pulmonary metastatic renal cell carcinoma. The histopathological diagnoses for six of these eight lesions were metastases from clear cell carcinoma of the kidney, one case was a metastasis from papillary renal cell carcinoma, and the remaining case was a metastasis from a poorly differentiated carcinoma including predominantly spindle cells, papillary cells, and clear cells.

RESULTS

The HRCT findings of all cases of clear cell carcinoma showed solid nodular lesions without ground-glass attenuation (GGA). The HRCT findings for one case of papillary renal cell carcinoma showed a lobulated nodule with a small amount of GGA in an area in the periphery and an air bronchogram. The HRCT findings of the remaining case of poorly differentiated carcinoma showed an ill-defined nodule with a GGA area and pleural indentations.

CONCLUSION

In brief, solitary pulmonary metastases from renal cell carcinoma may present as a smoothly marginated nodule, lobulated nodule, or a nodule with peripheral GGA.

Small cell lung carcinoma: Eight types of extension and spread on computed tomography

OBJECTIVE

The aim of this study was to classify the types of tumor extension and spread of small cell lung carcinoma (SCLC) and to recognize the unusual types of spread pattern of SCLC on computed tomography (CT) including multidetector row CT (MDCT) using contrast-enhanced material.

MATERIALS AND METHODS

Sixty-eight cases (53 men and 15 women aged 54-83 years old) of pathologically proven SCLC were examined mainly by contrast-enhanced CT scan. In surgically treated 7 cases, CT-pathologic correlations were performed.

RESULTS

Eight types of extension and spread were recognized by the examinations of chest CT. The type of central mass + mediastinal extension (n = 20 [29.4%]) was the most common manifestation. The types of central perihilar mass (n = 12 [17.6%]), peripheral mass + mediastinal extension (n = 14 [20.6%]), and peripheral mass (n = 7 [10.3%]) were frequently observed. The primary site of SCLC was in peripheral lung tissue in 21 of 68 cases (30.9%) in this study. Unusual CT manifestations, such as the types of lymphangitic spread (n = 6 [8.8%]), pleural dissemination (n = 4 [5.9%]), lobar replacement (n = 3 [4.4%]), pneumonialike air-space infiltrative spread (n = 2 [2.9%]) were recognized in our study. Stenosis of trachea and main bronchus caused by peribronchial extension were commonly noted. In the advanced cases with mediastinal extension, we observed the extension of SCLC to superior vena cava (n = 22), main pulmonary artery (n = 18), pulmonary vein (n = 11), and thoracic aortic wall (n = 7). Peri-and intracardial invasions were also observed in 9 cases.

CONCLUSIONS

Computed tomography including MDCT analysis revealed 8 types of extension and spread of SCLC including unusual forms in 68 SCLC cases. Peribronchial extension and great vessel wall involvement, such as superior vena cava, main pulmonary artery, and peri-/intra-cardial extension, were commonly observed in advanced stage.

Differential CT features of infectious pneumonia versus bronchioloalveolar carcinoma (BAC) mimicking pneumonia

The purpose of this study was to evaluate retrospectively the differential CT features of bronchioloalveolar carcinoma (BAC) mimicking pneumonia and infectious pneumonia at the lung periphery. CT images were reviewed in 47 patients with focal areas of parenchymal opacification at the lung periphery. We evaluated the presence of ground-glass attenuation, marginal conspicuity of the lesion, CT angiogram sign, air-bronchogram sign, a bubble-like low-attenuation area within the lesion, presence of pleural thickening and retraction associated with the lesion, presence of pleural effusion and extra-pleural fatty hypertrophy, presence of bronchial wall thickening proximal to the lesion, and air-trapping in the normal lung near the lesion. BAC (n=18) depicted the presence of a bubble-like low-attenuation area within the lesion, whereas infectious pneumonia (n=29) represented the pleural thickening associated with the lesion and bronchial wall thickening proximal to the lesion (P<0.05). The other CT findings showed no significant differences (P>0.05). The focal areas of the parenchymal opacification on the CT images may suggest infectious pneumonia rather than BAC when they show bronchial wall thickening proximal to the lesion and pleural thickening associated with the lesion, whereas BAC is characterized as the presence of a bubble-like low attenuation area within the tumor.

Prediction of lung adenocarcinoma without vessel invasion: a CT scan volumetric analysis

STUDY OBJECTIVES

Patients with lung adenocarcinoma without vessel invasion have a favorable prognosis after resection and are among the candidates for limited surgery. The purpose of the present study was to predict lung adenocarcinoma without vessel invasion based on a volumetric analysis of the lesion with a CT scan prior to the operation.

METHODS

CT scan images were obtained in 288 consecutive patients with adenocarcinoma of the lung before surgical resection. Total tumor volume, the volume of the nonsolid component, and the proportion occupied by the nonsolid component were calculated by the perimeter method. The performance of the derived logistic regression model and the volumetric results were evaluated by receiver operating characteristic analysis. The model derived for the prediction of tumors without vessel invasion was assessed by means of the leave-one-out cross-validation technique.

RESULTS

The pathologic diagnosis was adenocarcinoma with vessel invasion in 160 cases, and without vessel invasion in 128 cases. The median total tumor volume, the median volume of the nonsolid component, and median proportion occupied by the nonsolid component were 1,123.7 mm(3), 253.4 mm(3), and 58.0%, respectively. With the derivation of the predictive rule, stepwise regression yielded the following five features: the proportion occupied by the nonsolid component; spiculation; pleural indentation; gender; and tumor size. The Az value, a measure of diagnostic power represented as the area under the curve, was 0.957 for prediction of lung adenocarcinoma without vessel invasion. The cross-validation accuracy achieved by applying the rule was 90.3%.

CONCLUSIONS

The proportion occupied by the nonsolid component based on a CT scan volumetric analysis was a reliable predictor of tumors without vessel invasion in patients with adenocarcinoma of the lung.

Mucin-producing adenocarcinoma of the lung: thin-section computed tomography findings in 48 patients and their effect on prognosis

OBJECTIVE

To determine the prognostic value of thin-section computed tomography (CT) findings in patients with mucin-producing adenocarcinoma (MPA) of the lung.

METHODS

The study included 48 patients with pathologically proven MPA who had thin-section CT before treatment. The CT findings were correlated with the histopathologic findings and with disease-free survival on follow-up in all patients.

RESULTS

Computed tomography findings identified in patients with MPA of the lung included an air bronchogram (n = 37, 77.1%), areas of ground-glass attenuation (n = 36, 75.0%), areas of air-space consolidation (n = 36, 75.0%), interlobular septal thickening (n = 33, 68.8%), bubble-like lucencies (n = 23, 47.9%), centrilobular nodules (n = 22, 45.8%), and mucus filling of airways (n = 19, 39.6%). Twenty-two (45.8%) of the 48 patients had intrapulmonary metastases. Centrilobular nodules (odds ratio [OR] = 6.7, 95% confidence interval: 1.1-41.4; P < 0.05) and mucus filling of airways (OR = 14.4, 95% 95% confidence interval: 2.0-102.7; P < 0.01) on thin-section CT were independently associated with an increased likelihood of intrapulmonary metastases. The 5-year disease-free survival rates were 67.9% and 38.4% for patients without and with intrapulmonary metastases, respectively (P < 0.05). The presence of centrilobular nodules (relative risk = 10.5, 95% confidence interval: 1.8-59.3; P < 0.01) on thin-section CT was an independent predictor of poor prognosis.

CONCLUSION

Centrilobular nodules on CT are associated with a higher prevalence of intrapulmonary metastases and a poor prognosis in patients with MPA of the lung.

"Crazy-paving" pattern at thin-section CT of the lungs: radiologic-pathologic overview

The "crazy-paving" pattern is a common finding at thin-section computed tomography (CT) of the lungs. It consists of scattered or diffuse ground-glass attenuation with superimposed interlobular septal thickening and intralobular lines. This finding has a variety of causes, including infectious, neoplastic, idiopathic, inhalational, and sanguineous disorders. Specific disorders that can cause the crazy-paving pattern include Pneumocystis carinii pneumonia, mucinous bronchioloalveolar carcinoma, pulmonary alveolar proteinosis, sarcoidosis, nonspecific interstitial pneumonia, organizing pneumonia, exogenous lipoid pneumonia, adult respiratory distress syndrome, and pulmonary hemorrhage syndromes. Knowledge of the many causes of this pattern can be useful in preventing diagnostic errors. In addition, although the causes of this pattern are frequently indistinguishable at radiologic evaluation, differences in the location of the characteristic attenuation in the lungs, as well as the presence of additional radiologic findings, the patient's history, and the clinical presentation, can often be useful in suggesting the appropriate diagnosis.

A clinicopathological study of resected subcentimeter lung cancers: a favorable prognosis for ground glass opacity lesions

BACKGROUND

Owing to the advent of refined chest computed tomography (CT) images with higher resolution and CT screening programs, more faint and smaller lung cancers are being discovered. These include small-sized lung cancers such as those with a subcentimeter diameter, which had never been picked up on the routine chest roentgenogram films. However their clinicopathological characteristics with special reference to the proper surgical mode are not fully described so far.

METHODS

During a 10-year period from 1991 through 2000 a total of 1,769 lung tumors were resected at the National Cancer Center Hospital, Tokyo. According to the pathology files of these patients, 51 patients had a primary tumor with the diameter of 1 cm or less. Three tumors arising in the bronchial lumina of hilum with a squamous cell carcinoma histology were excluded and the remaining 48 tumors of peripheral origin were studied. The clinicopathological features were analyzed according to three types of appearance on high-resolution CT: non-solid ground glass opacity (GGO) type (n = 19); part-solid GGO type (n = 9); and solid type (n = 20). Non-solid GGO is made up of homogeneous moderate increased density on CT, which cannot obscure the bronchovascular structure, whereas partly solid GGO contains a mere solid part but did not exceed 50% of the whole area (n = 9). All other lesions were considered solid type.

RESULTS

For the three types of lesions, the distribution of age and sex was similar with the average age of 61 years and an almost even distribution of male/female patients. Although 6 patients had symptoms, the symptoms were not associated with the nodule itself. Twenty-six patients (54%) were screen-detected (16 chest roentgenogram films and 10 CT scans) and the others were detected by incidentally taken chest roentgenogram film or CT for other reasons than nodules detected. Two squamous carcinomas were positive for sputum cytology. Preoperative cytologic/histologic diagnosis was given in 14 patients (29%). The histologic type of GGO lesion was bronchioloalveolar carcinoma in all 28 cases. In solid lesions, besides 16 adenocarcinomas 2 cases of squamous cell carcinoma, 1 case each of small cell carcinoma and carcinoid tumor was seen. Lymph node involvement was seen only in 3 patients with solid lesions (N1 in 2 patients, N2 in 1 patient). As for operative mode, the limited resection was performed for 15 GGO lesions (54%) and 4 solid lesions (20%). Tumor recurrence was seen in 2 patients with solid lesions-1 in bone and the other in locoregional lymph node, and the former died of disease.

CONCLUSIONS

Among subcentimeter lung cancers, GGO lesions (both non-solid and part-solid) constitute true early lung cancers. Since they have minimal or no invasive growth, limited resection for cure is justified. Conversely the solid lesion had significant invasive features such as lymph node metastasis. Lobectomy should remain as the standard mode of surgery despite such small size.

Reclassification of cystic bronchioloalveolar carcinomas to adenocarcinomas based on the revised World Health Organization Classification of Lung and Pleural Tumours

The objective of this study was to evaluate the radiologic-pathologic correlation of cystic change in cases of bronchioloalveolar carcinoma (BAC) using the 1999 revised World Health Organization Classification of Lung and Pleural Tumours. A total of 304 cases diagnosed as BAC before 1999 were reviewed retrospectively for radiologic findings of cystic change (n = 31). Of these, 20 had adequate clinical, pathologic, and radiologic material available for review. Patient demographics and history; the method, location, and size of specimen biopsy; and pathology reports were evaluated. A pulmonary pathologist reviewed the microscopic findings to confirm the diagnosis based on the 1999 World Health Organization criteria. Chest radiographs (n = 20) and computed tomographic scans (n = 11) were analyzed for location, size, and multiplicity of pulmonary nodules, masses, consolidations, or characterization of cystic change. Associated findings of lymphadenopathy, pleural effusion, atelectasis, and underlying lung disease were noted. There were 10 men and 10 women (mean age, 49.3 years) who participated in the study. Eleven were symptomatic. Pathologic review, based on the revised World Health Organization classification, yielded the diagnosis of adenocarcinoma (n = 14); adenocarcinoma, possible BAC (n = 4); and BAC (n = 2). Radiologically, adenocarcinoma (n = 14) manifested as a solitary pulmonary nodule/mass (n = 5) or consolidation (n = 6) and as multifocal mixed disease (n = 3) with solitary (n = 8) or multicystic (n = 6) change. Adenocarcinoma, possible BAC (n = 4) manifested as multifocal and multicystic consolidations (n = 2) or mixed disease (n = 1) and as a solitary cystic mass (n = 1). BAC (n = 2) manifested as a cystic mass (n = 1) and as multifocal multicystic mixed disease (n = 1). Most cases of BAC with radiologic cystic change were reclassified as adenocarcinoma. The radiologic features of BAC may need to be redefined in light of the current diagnostic criteria to help identify patients with limited and potentially curable disease.

Bronchioloalveolar carcinoma and adenocarcinoma with bronchioloalveolar features presenting as ground-glass opacities on CT

OBJECTIVE

As bronchioloalveolar carcinoma (BAC) is noninvasive but, in its later stages, has a worse prognosis than adenocarcinoma with bronchioloalveolar features (ACB), early identification and differentiation is important for therapeutic and prognostic purposes. We wanted to identify features of BAC, which differentiated it from ACB when both presented as ground-glass opacities (GGOs) on CT.

MATERIALS AND METHODS

We reviewed all pathologic specimens of patients who were diagnosed with BAC and ACB in the lung from 1991 to 1999 in our institution and whose malignancy presented as a GGO on CT. This yielded 29 patients, 15 with BAC and 14 with ACB with GGOs on CT. Both univariate frequency table and multivariate logistic regression approaches were used to analyze the CT characteristics of these GGOs (location, GGO pattern, size, shape, margin, presence and type of air bronchogram and pseudocavitation).

RESULTS

BAC most frequently had a "GGO halo" around a solid opacity, often was a GGO "mixed with consolidation" with the smallest BACs being "pure GGO." Air bronchograms were frequently present in the largest GGOs. Pseudocavitations were rare. ACB, on the other hand, most frequently presented as a GGO "mixed with consolidation," less frequently with a "GGO halo" and rarely with "superimposed lymphangitis." The air bronchograms, frequently present, were usually tortuous and ectatic. Pseudocavitation was present in about one-third of the cases. The most useful CT features of GGO in separating those due to BAC from those due to ACB were pure (uniform) ground-glass attenuation and absence of lymphangitis.

CONCLUSION

The CT features of BAC and ACB presenting as GGO reflect the histologic descriptions of these carcinomas.

CARCINOMA BRONQUÍOLO-ALVEOLAR: ASPECTOS NA TOMOGRAFIA COMPUTADORIZADA DE ALTA RESOLUÇÃO

O carcinoma bronquíolo-alveolar é um tipo de carcinoma broncogênico de crescimento insidioso, que surge nas paredes das vias aéreas distais e se dissemina utilizando o septo alveolar como um estroma, preservando a arquitetura pulmonar. Neste trabalho foram analisadas as tomografias computadorizadas de alta resolução de 17 pacientes com carcinoma bronquíolo-alveolar. Ao contrário do relatado na literatura, foram observados predomínio no sexo masculino (71%) e maior freqüência da associação das formas de consolidação e multinodular (53%) em relação à forma nodular solitária (12%), multinodular (12%) e de consolidação (23%). Os aspectos mais encontrados foram: áreas de consolidação (76%), broncograma aéreo (71%), áreas de baixa atenuação provavelmente devidas à presença de muco (60%), espessamento de septos interlobulares, opacidades em vidro fosco e nódulos confluentes (54% cada), e pavimentação em mosaico (36%). Os nódulos cavitados, a atelectasia, o sinal do halo e o aspecto de "árvore em brotamento" foram observados em apenas um caso cada.

Peripheral lung adenocarcinoma: correlation of thin-section CT findings with histologic prognostic factors and survival

PURPOSE

To evaluate the prognostic importance of thin-section computed tomographic (CT) findings of peripheral lung adenocarcinomas.

MATERIALS AND METHODS

The subjects were 127 patients with adenocarcinomas smaller than 3 cm in largest diameter who underwent at least a lobectomy with hilar and mediastinal lymphadenectomy. The margin characteristics of nodules and the extent of ground-glass opacity (GGO) within the nodules at preoperative thin-section CT were analyzed retrospectively. Regional lymph node metastasis (LNM) and vessel invasion (VI) were histologically examined in surgical specimens. Survival curves were calculated according to the Kaplan-Meier method.

RESULTS

The frequencies of LNM (4% [1 of 24]) and VI (13% [three of 24]) in adenocarcinomas with GGO components of more than 50% were significantly lower than those with GGO components of less than 10% (LNM, P <.05; VI, P <.01). The patients with GGO components of more than 50% showed a significantly better prognosis than those with GGO components less than 50% (P <.05). All 17 adenocarcinomas smaller than 2 cm with GGO components of more than 50% were free of LNM and VI, and all these patients are alive without recurrence. Coarse spiculation and thickening of bronchovascular bundles around the tumors were observed more frequently in tumors with LNM or VI than in those without LNM or VI (P <.01).

CONCLUSION

Thin-section CT findings of peripheral lung adenocarcinomas correlate well with histologic prognostic factors.

CT differentiation of pneumonic-type bronchioloalveolar cell carcinoma and infectious pneumonia

The objective was to analyse the potential of CT to distinguish pneumonic-type bronchioloalveolar cell carcinoma (BAC) from infectious pneumonia. The study consisted of 21 patients with pathologically proven BAC and 30 patients with infectious pneumonia. Both groups of patients had patchy or diffuse consolidation of more than half the area of a lobe or lobes on CT. CT findings in these two groups were compared with regard to morphological appearance, including CT angiogram, air bronchogram, mucous bronchogram, contrast enhancement pattern, pseudocavitation, cavity with air-fluid level, location, satellite lesion, ground-glass opacity and bulging of the interlobar fissure. Air-filled bronchi were morphologically analysed as dilatation, stretching, sweeping, widening of the branching angle, squeezing and crowding. Lymphadenopathy and pleural effusion were also analysed. CT findings favouring the diagnosis of BAC included an air-filled bronchus within the consolidation with stretching, squeezing, sweeping, widening of the branching angle and bulging of the interlobar fissure (p<0.05). It is concluded that CT may be helpful in differentiating pneumonic-type BAC from infectious pneumonia if the air-filled bronchus within the consolidation shows stretching, squeezing, widening of the branching angle or bulging of the interlobar fissure.

Bronchioloalveolar cell carcinoma: impact of histology on dominant CT pattern

The authors set out to determine how histologic variability in bronchioloalveolar cell carcinoma impacts dominant radiographic patterns shown by computed tomography (CT). Thoracic CT's of all patients with pathologically confirmed bronchioloalveolar cell carcinoma diagnosed over a 36-month period were reviewed without knowledge of underlying histologic type. The dominant CT pattern was recorded as 1) air space consolidation; 2) focal nodule or mass; and 3) multicentric nodules or masses. Nodules and masses were further characterized according to borders, distribution, and associated findings, including spiculations and air bronchograms. Histology was independently reviewed. Twenty-seven patients, 16 women and 11 men, mean age 60 years, were diagnosed with bronchioloalveolar cell carcinoma. In 6 (22%) of the 27 cases, the histology was mucinous, with malignant goblet cells identified. Five (83%) of the six mucinous neoplasms manifested as air space consolidation and three (50%) of the six presented with multiple nodules, in which two had coexisting air space consolidation. Of the remaining 21 cases (78%) with nonmucinous histology, the primary malignant cells of origin included Clara cells (n = 8), tall columnar epithelial cells (n = 7) and alveolar type II pneumocytes (n = 6). Sclerosis was a dominant histologic feature in 14 (67%) of the 21 cases. Seventeen (81%) of the nonmucinous neoplasms presented as isolated nodules or masses and four (19%) presented as multiple nodules or masses. Of these four patients with multifocal disease and nonmucinous histology, multiple bronchioloalveolar adenomas accounted for multicentricity in two of the patients. Significant correlations included air space consolidation with mucinous histology (p = 0.001) and focal nodule or mass with nonmucinous histology (p = 0.001). At CT of bronchioloalveolar cell carcinoma, the patterns of air-space consolidation correlate with mucinous histology and isolated nodules or masses with nonmucinous histology. The pattern of multiple nodules or masses, however, did not correlate with histology. Coexisting bronchioloalveolar adenomas can contribute to apparent multicentric disease in patients with nonmucinous histology.

Evolution of peripheral lung adenocarcinomas: CT findings correlated with histology and tumor doubling time

OBJECTIVE

This study was performed to evaluate the evolution of peripheral lung adenocarcinomas using CT findings and histologic classification related to tumor doubling time.

MATERIALS AND METHODS

The subjects were 34 patients, each with an adenocarcinoma smaller than 3 cm. All patients underwent chest radiography and 10 of them had previously undergone CT more than 6 months before surgery. Tumor doubling time was estimated by examining sequential radiographs using the method originally described by Schwartz. Tumor growth was also observed by studying the changes on CT in the 10 patients who had previously undergone CT. The histologic classification (types A-F) was evaluated according to the criteria of Noguchi et al.

RESULTS

Five (83%) of the six adenocarcinomas with tumor types A or B showed localized ground-glass opacity on high-resolution CT. All six tumors had a tumor doubling time of more than 1 year. Fifteen (71%) of the 21 tumors with type C showed partial ground-glass opacity mixed with localized solid attenuation on high-resolution CT. Ten (48%) of these 21 type C tumors had a tumor doubling time of more than 1 year. In types B and C, the solid component or the development of pleural indentation and vascular convergence increased during observation before surgery. All seven tumors with types D, E, and F showed mostly solid attenuation, and the tumor doubling time was less than 1 year in six (87%) of the seven tumors.

CONCLUSION

Two main types of peripheral lung adenocarcinoma exist. The first type appears on CT as a localized ground-glass opacity with slow growth, and the other appears as a solid attenuation with rapid growth.

Magnetic resonance imaging of bronchioloalveolar carcinoma

The purpose of this study is to describe the magnetic resonance (MR) features of bronchioloalveolar carcinoma. MR examinations of 18 patients with proven bronchioloalveolar carcinoma were reviewed. Detection at computed tomography (CT) and pathologic confirmation were the entry criteria. Nine patients had a solitary nodule, three patients a lobar consolidation, and six patients had diffuse disease. For each patient, both breath-hold T2-weighted fast spin-echo, and breath-hold T1-weighted gradient-echo images, before and after injection of gadolinium, were available. Nine patients with pulmonary consolidation or diffuse disease had also heavily T2-weighted MR imaging (Haste or TSE 240; Siemens, Erlangen, Germany). MR imaging showed pulmonary abnormalities in 17 of 18 patients. Unenhanced T1-weighted and T2-weighted images depicted tumor in 16 of 18 patients. Contrast-enhanced T1-weighted images showed tumor in 17 of 18 patients. In no case did MR imaging depict abnormalities corresponding to the ground-glass opacities seen on CT scans. In three patients with mucinous bronchioloalveolar carcinoma, heavily T2-weighted images showed lesions isointense with respect to static fluid of the human body. In conclusion, the ability of MR imaging in detecting small nodules and ground-glass opacities is limited. However, heavily T2-weighted sequences are able to show the presence of mucin. This is useful information because mucinous bronchioloalveolar carcinoma carries a poor prognosis.

Nonresolving or slowly resolving pneumonia

Given the variability in rate of radiographic resolution, it remains controversial to decide when to initiate an invasive diagnostic work-up for nonresolving or slowly resolving pulmonary infiltrates. In immunocompetent patients who present with classical features of CAP (i.e., fever, chills, productive cough, new pulmonary infiltrate), clinical response to therapy is the most important determinant for further diagnostic studies. Within the first few days, persistence or even progression of infiltrates on chest radiographs is not unusual. Defervescence, diminished symptoms, and resolution of leukocytosis strongly support a response to antibiotic therapy, even when chest radiographic abnormalities persist. In this context, observation alone is reasonable, and invasive procedures can be deferred. Serial radiographs and clinical examinations dictate subsequent evaluation. In contrast, when clinical improvement has not occurred and chest radiographs are unchanged or worse, a more aggressive approach is warranted. In this setting, we advise fiberoptic bronchoscopy with BAL and appropriate cultures for bacteria, legionella, fungi, and mycobacteria. When endobronchial anatomy is normal and there is no purulence to suggest infection, TBBs should be done to exclude noninfectious causes (discussed earlier) or infections attributable to mycobacteria or fungi. An aggressive approach is also warranted in patients who are clinically stable or improving when the rate of radiographic resolution is delayed. As discussed earlier, what constitutes excessive delay is controversial, and depends upon the acuity of illness, specific pathogen, extent of involvement (i.e., lobar versus multilobar), comorbidities, and diverse host factors. Stable infiltrates even 2 to 4 weeks after institution of antibiotic therapy does not mandate intervention provided patients are improving clinically. Invasive techniques can also be deferred when unequivocal, albeit incomplete, radiographic resolution can be demonstrated. Lack of at least partial radiographic resolution by 6 weeks, even in asymptomatic patients, however, deserves consideration of alternative causes (e.g., endobronchial obstructing lesions, or noninfectious causes). Fiberoptic bronchoscopy with BAL and TBBs has minimal morbidity and is the preferred initial invasive procedure for detecting endobronchial lesions or substantiating noninfectious causes. The yield of bronchoscopy depends on demographics, radiographic features, and pre-test likelihood. In the absence of specific risk factors, the incidence of obstructing lesions (e.g., bronchogenic carcinomas, bronchial adenomas, obstructive foreign body) is low. Bronchogenic carcinoma is rare in nonsmoking, young (< 50 years) patients but is a legitimate consideration in older patients with a history of tobacco abuse. Non-neoplastic causes (e.g., pulmonary vasculitis, hypersensitivity pneumonia, etc.) should be considered when specific features are present (e.g., hematuria, appropriate epidemiologic exposures). Ancillary serologic tests or biopsies of extrapulmonary sites are invaluable in some cases. In rare instances, surgical (open or VATS) biopsy is necessary to diagnose refractory or non-resolving "pneumonias."

Bronchioloalveolar carcinoma with widespread ground-glass shadow on CT in two cases

Two cases of bronchioloalveolar carcinomas are presented. In both cases, chest CT demonstrated widespread ground-glass shadows. The findings on CT revealed tumor tissue character with tumor cell proliferation along the alveolar wall and air in the alveoli.

Air-space pattern in lung metastasis from adenocarcinoma of the GI tract

PURPOSE

We retrospectively reviewed a series of proven lung metastasis to evaluate the frequency and CT features of metastases showing an air-space (lepidic) pattern of growth.

METHOD

CT examinations of 65 patients with proven lung metastasis from GI carcinomas were reviewed by three observers. Four CT features were used to classify lesions as air-space metastases: (a) air-space nodules; (b) parenchymal consolidation containing air bronchogram and/or showing angiogram sign; (c) focal or extensive ground-glass opacities; and (d) nodules(s) with a "halo" sign.

RESULTS

Six of 65 patients showed air-space metastases: three from pancreatic carcinoma, two from colonic carcinoma, and one from jejunal carcinoma. In one case, metastasis appeared as extensive parenchymal consolidation associated with ground-glass opacities; in one as an area of ground-glass opacity; in one as an extensive parenchymal consolidation with air bronchogram; in one as parenchymal consolidations with angiogram sign and multiple nodules, some of these with halo sign; in one as air-space nodules and patchy air-space consolidations; and in one as a solitary nodule with halo sign.

CONCLUSION

Our study shows that air-space lung metastasis from GI carcinomas is uncommon but not rare. On CT as well as microscopically, differential diagnosis between air-space metastasis and bronchioloalveolar carcinoma may be impossible.