Mucinous versus nonmucinous solitary pulmonary nodular bronchioloalveolar carcinoma: CT and FDG PET findings and pathologic comparisons

Case of lung fine needle aspiration showing mucinous cells and extracellular mucin

Mucinous neoplasm with extracellular mucin can be challenging to interpret on fine needle aspiration and core biopsies. Determining the biologic origin of the mucin/mucinous cells, that is, benign/incidental versus neoplasm, invasive versus in situ, and primary versus metastatic tumors, requires a thorough multidisciplinary evaluation. The work up of these lesions includes morphologic analysis with ancillary immunohistochemical and/or molecular studies and correlation with clinical and imaging studies. This review outlines a practical approach to the diagnosis of mucinous lesions in the lung with comprehensive review of literature.

Multidimensional biological characteristics of ground glass nodules

The detection rate of ground glass nodules (GGNs) has increased in recent years because of their malignant potential but relatively indolent biological behavior; thus, correct GGN recognition and management has become a research focus. Many scholars have explored the underlying mechanism of the indolent progression of GGNs from several perspectives, such as pathological type, genomic mutational characteristics, and immune microenvironment. GGNs have different major mutated genes at different stages of development; EGFR mutation is the most common mutation in GGNs, and p53 mutation is the most abundant mutation in the invasive stage of GGNs. Pure GGNs have fewer genomic alterations and a simpler genomic profile and exhibit a gradually evolving genomic mutation profile as the pathology progresses. Compared to advanced lung adenocarcinoma, GGN lung adenocarcinoma has a higher immune cell percentage, is under immune surveillance, and has less immune escape. However, as the pathological progression and solid component increase, negative immune regulation and immune escape increase gradually, and a suppressive immune environment is established gradually. Currently, regular computer tomography monitoring and surgery are the main treatment strategies for persistent GGNs. Stereotactic body radiotherapy and radiofrequency ablation are two local therapeutic alternatives, and systemic therapy has been progressively studied for lung cancer with GGNs. In the present review, we discuss the characterization of the multidimensional molecular evolution of GGNs that could facilitate more precise differentiation of such highly heterogeneous lesions, laying a foundation for the development of more effective individualized treatment plans.

Clinicopathologic Features and Survival Outcomes of Primary Lung Mucinous Adenocarcinoma Based on Different Radiologic Subtypes

BACKGROUND

Primary lung mucinous adenocarcinomas (LMAs) could be subclassified as the pure-solid, part-solid, and pneumonic types according to the findings of high-resolution computed tomography. This study aimed to expound on the clinicopathologic, radiologic, and prognostic characteristics of LMAs based on radiologic classification within a large set of patients.

METHODS

From November 2009 to December 2016, this study enrolled 294 resected LMAs, which were divided into the pure-solid (n = 169), part-solid (n = 87), and pneumonic (n = 38) types. The clinicopathologic and radiologic characteristics of the tumors were evaluated, and patient prognosis was determined through follow-up evaluation. Survival outcomes were calculated by Kaplan-Meier curves and compared using log-rank tests. The prognostic impact of clinicopathologic variables, including radiologic presentations, were evaluated by establishing a Cox proportional hazards model.

RESULTS

The LMAs were infrequently associated with lymph node metastasis (5.4 %), lymphatic/vascular invasion (4.4 %), or visceral pleural invasion (5.1 %). During the median 71-month follow-up period, recurrence was observed in 62 patients and death in 44 patients. The patients with pneumonic-type LMAs had a poorer prognosis (5-year recurrence-free survival [RFS], 23.7 %; 5-year overall survival [OS], 44.7 %) than those with the pure-solid type (RFS, 83.2 %; OS, 100 %) or part-solid type (RFS, 93.7 %; OS, 100 %). Besides, lymph node metastasis, emphysema, and clinical T stage were independent predictors of RFS and OS.

CONCLUSION

Solitary-type LMA patients had excellent prognoses, whereas the survival outcomes for pneumonic-type LMA patients were dismal. Furthermore, pneumonic-type LMA patients were prone to intrapulmonary metastasis by means of aerogenous dissemination rather than distant metastasis.

Invasive mucinous adenocarcinoma of the lung: clinicopathological features, 18F-FDG PET/CT findings, and survival outcomes

OBJECTIVE

Invasive mucinous adenocarcinoma (IMA) is a rare subtype of lung adenocarcinoma. This study aimed to retrospectively evaluate the clinicopathological features, ¹⁸F-FDG PET/CT findings, and prognosis of IMA of the lung, as well as to investigate the associations among these variables, to improve the management of such patients.

METHODS

Clinicopathological and ¹⁸F-FDG PET/CT characteristics of 72 patients with pathologically confirmed IMA of the lung were retrospectively collected and investigated, and their predictive efficacy on progression-free survival (PFS) was evaluated.

RESULTS

The median age of the enrolled 72 patients was 61 years (range, 26-79 years), and the male-to-female ratio was 1:1.25. According to the radiological morphology of IMA, solidary nodule/mass type (n = 59, 81.9%) was the most common, followed by GGO type (n = 8, 11.1%) and pneumonia type (n = 5, 6.9%). Lobulated or spiculated margin and pleural traction were the most common radiological signs. The median SUVmax of IMA lesions was 3.0, ranging from 0.5 to 23.1. Higher SUVmax was observed in IMA with non-GGO type, clinical symptom, advanced stage, lobulated margin, pleural traction or spread through air spaces (STAS) (P < 0.05). Moreover, higher SUVmax was related to larger tumor size in non-pneumonia-type IMA (r = 0.708, P < 0.001). The median PFS was 21.3 months, and the 12-, 24- and 36-month PFS rates were 89.8%, 83.3% and 75.5%, respectively. A poorer PFS was significantly associated with SUVmax ≥ 3, advanced stage and STAS.

CONCLUSION

¹⁸F-FDG PET/CT combined with clinicopathological characteristics can aid the diagnosis and prognostic evaluation of lung IMA, which could provide guidance for the appropriate management of such patients.

Qualitative and Semiquantitative Parameters of 18F-FDG-PET/CT as Predictors of Malignancy in Patients with Solitary Pulmonary Nodule

This study aims to evaluate the reliability of qualitative and semiquantitative parameters of ¹⁸F-FDG PET-CT, and eventually a correlation between them, in predicting the risk of malignancy in patients with solitary pulmonary nodules (SPNs) before the diagnosis of lung cancer. A total of 146 patients were retrospectively studied according to their pre-test probability of malignancy (all patients were intermediate risk), based on radiological features and risk factors, and qualitative and semiquantitative parameters, such as SUVmax, SUVmean, TLG, and MTV, which were obtained from the FDG PET-CT scan of such patients before diagnosis. It has been observed that visual analysis correlates well with the risk of malignancy in patients with SPN; indeed, only 20% of SPNs in which FDG uptake was low or absent were found to be malignant at the cytopathological examination, while 45.45% of SPNs in which FDG uptake was moderate and 90.24% in which FDG uptake was intense were found to be malignant. The same trend was observed evaluating semiquantitative parameters, since increasing values of SUVmax, SUVmean, TLG, and MTV were observed in patients whose cytopathological examination of SPN showed the presence of lung cancer. In particular, in patients whose SPN was neoplastic, we observed a median (MAD) SUVmax of 7.89 (±2.24), median (MAD) SUVmean of 3.76 (±2.59), median (MAD) TLG of 16.36 (±15.87), and a median (MAD) MTV of 3.39 (±2.86). In contrast, in patients whose SPN was non-neoplastic, the SUVmax was 2.24 (±1.73), SUVmean 1.67 (±1.15), TLG 1.63 (±2.33), and MTV 1.20 (±1.20). Optimal cut-offs were drawn for semiquantitative parameters considered predictors of malignancy. Nodule size correlated significantly with FDG uptake intensity and with SUVmax. Finally, age and nodule size proved significant predictors of malignancy. In conclusion, considering the pre-test probability of malignancy, qualitative and semiquantitative parameters can be considered reliable tools in patients with SPN, since cut-offs for SUVmax, SUVmean, TLG, and MTV showed good sensitivity and specificity in predicting malignancy.

Prognosis of resected invasive mucinous adenocarcinoma compared with the IASLC histologic grading system for invasive nonmucinous adenocarcinoma: Surgical database study in the TKIs era in Korea

BACKGROUND

The prognosis of invasive mucinous adenocarcinoma (IMA) remains controversial and should be clarified by comparison with the International Association for the Study of Lung Cancer (IASLC) histologic grading system for invasive nonmucinous adenocarcinoma (INMA).

METHODS

This study included patients with IMA who underwent curative resection. Their clinicopathological outcomes were compared with those of patients with INMA. Propensity score matching was performed to compare the prognosis of IMA with IASLC grade 2 or 3. Kaplan-Meier survival curves and log-rank tests were used to analyze recurrence-free survival (RFS) and overall survival (OS).

RESULTS

The prognoses of IMA and IASLC grade 2 were similar in terms of RFS and OS. Although patients with IMA had better RFS than patients with IASLC grade 3, the OS was not significantly different. After propensity score matching, IMA demonstrated similar RFS to IASLC grade 2 but superior to IASLC grade 3; there was no difference in the OS compared with grades 2/3. Multivariate analysis revealed that tumor size (hazard ratio [HR] = 1.20, p = 0.028), lymphovascular invasion (HR = 127.5, p = 0.003), and maximum standardized uptake value (HR = 1.24, p = 0.005) were poor prognostic predictors for RFS. Patients with IMA demonstrated RFS similar to and significantly better than that of patients with IASLC grades 2 and 3, respectively. For OS, IMA prognosis was between that of IASLC grades 2 and 3.

CONCLUSIONS

Since the prognosis of IMA among lung adenocarcinomas appears to be relatively worse, further clinical studies investigating IMA-specific treatment and follow-up plans are necessary to draw more inferences.

A Case of Invasive Mucinous Adenocarcinoma with Acute Respiratory Distress Syndrome Diagnosed by Autopsy Findings

We herein report a fatal case of invasive mucinous adenocarcinoma (IMA) with acute respiratory distress syndrome (ARDS) diagnosed based on autopsy findings. A 76-year-old man presented with severe respiratory discomfort on admission. Computed tomography (CT) revealed a peripheral distribution of consolidation. Although his respiratory status improved after steroid therapy, re-exacerbation occurred, and the patient died on day 131. A bronchoscopic lung biopsy had shown organizing pneumonia, but a post-mortem examination surprisingly revealed IMA with organizing pneumonia. IMA presenting with ARDS as the first symptom is extremely rare.

Recurrence dynamics after curative surgery in patients with invasive mucinous adenocarcinoma of the lung

Background

We investigated the patterns and timing of recurrence and death as well as prognostic factors based on clinicopathological and radiological factors in patients who underwent surgical treatment for invasive mucinous adenocarcinoma (IMA).

Methods

We reviewed clinicopathological findings including spread through air spaces (STAS) and CT findings of IMA such as morphology, solidity, margin, well-defined heterogeneous ground-glass opacity, CT angiogram, and air bronchogram signs from 121 consecutive patients who underwent surgical resection. Prognostic factors for disease-free survival (DFS) and overall survival (OS) were identified. Hazard rate analyses were performed for the survival dynamics.

Results

T stage (hazard ratio [HR] = 4.102, p = 0.03), N stage (N2 vs. N0, HR = 7.653, p < 0.001), and consolidative CT morphology (HR = 3.556, p = 0.008) remained independent predictors for DFS. Age (HR = 1.110, p = 0.002), smoking (HR = 12.893, p < 0.001), T stage (HR = 13.005, p = 0.006), N stage (N2 vs. N0, HR = 7.653, p = 0.004), STAS (HR = 7.463, p = 0.008), and consolidative CT morphology (HR = 6.779, p = 0.007) remained independent predictors for OS. Consolidative morphology, higher T and N stage, and presence of STAS revealed initial sharp peaks after steep decline of the hazard rate curves for recurrence or death in follow-up period.

Conclusions

Consolidative morphology, higher T and N stage, smoking, and STAS were indicators of significantly greater risk of early recurrence or death in patients with IMA. Thus, these findings could be incorporated into future surveillance strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-022-01208-5.

Genomic characteristics of invasive mucinous adenocarcinoma of the lung with multiple pulmonary sites of involvement

Invasive mucinous adenocarcinoma (IMA) of the lung frequently presents with diffuse pneumonic-type features or multifocal lesions, which are regarded as a pattern of intrapulmonary metastases. However, the genomics of multifocal IMAs have not been well studied. We performed whole exome sequencing on samples taken from 2 to 5 regions in seven patients with synchronous multifocal IMAs of the lung (24 regions total). Early initiating driver events, such as KRAS, NKX2-1, TP53, or ARID1A mutations, are clonal mutations and were present in all multifocal IMAs in each patient. The tumor mutational burden of multifocal IMAs was low (mean: 1.13/mega base), but further analyses suggested intra-tumor heterogeneity. The mutational signature analysis found that IMAs were predominantly associated with endogenous mutational process (signature 1), APOBEC activity (signatures 2 and 13), and defective DNA mismatch repair (signature 6), but not related to smoking signature. IMAs synchronously located in the bilateral lower lobes of two patients with background usual interstitial pneumonia had different mutation types, suggesting that they were double primaries. In conclusion, genomic evidence found in this study indicated the clonal intrapulmonary spread of diffuse pneumonic-type or multifocal IMAs, although they can occur in multicentric origins in the background of usual interstitial pneumonia. IMAs exhibited a heterogeneous genomic landscape despite the low somatic mutation burden. Further studies are warranted to determine the clinical significance of the genomic characteristics of IMAs in expanded cohorts.

Managing of screening-detected sub-solid nodules-a European perspective

Since the National Lung Screening Trial in 2011 showed a 20% reduction in lung cancer mortality using annual low-dose computed tomography (LDCT), several randomised controlled trials and studies have been started in Europe. These include the Italian lung study (ITALUNG), the Dutch-Belgian lung cancer screening trial (NELSON), the UK lung cancer screening trial (UKLS), the Detection and screening of early lung cancer with novel imaging technology (DANTE), the Danish lung cancer screening trial (DLCST), the German lung cancer screening intervention trial (LUSI), the Multicentric Italian lung detection trial (MILD) and the CT screening for lung cancer study (COSMOS). As a result of the increasing number of screening trials and the growing utilization of LDCT, the high detection of subsolid nodules is an increasingly important clinical problem. In the last few years, several guidelines have been published and providing guidance on the optimal management of subsolid nodules, but many controversies still exist. Follow-up imaging plays an important role in clinical assessment and subsequent management of this particular type of lung nodules, since they can be transient inflammatory lesions, and if persistent they can be both benign lesions or lung cancers of variable clinical behaviour. However, the vast majority of subsolid nodules retain an indolent course over many years. The aim of this review is to present a European perspective in management of screening detected subsolid nodules.

Primary Invasive Mucinous Adenocarcinoma of the Lung: Prognostic Value of CT Imaging Features Combined with Clinical Factors

Objective

To investigate the association between CT imaging features and survival outcomes in patients with primary invasive mucinous adenocarcinoma (IMA).

Materials and Methods

Preoperative CT image findings were consecutively evaluated in 317 patients with resected IMA from January 2011 to December 2015. The association between CT features and long-term survival were assessed by univariate analysis. The independent prognostic factors were identified by the multivariate Cox regression analyses. The survival comparison of IMA patients was investigated using the Kaplan-Meier method and propensity scores. Furthermore, the prognostic impact of CT features was assessed based on different imaging subtypes, and the results were adjusted using the Bonferroni method.

Results

The median follow-up time was 52.8 months; the 5-year disease-free survival (DFS) and overall survival rates of resected IMAs were 68.5% and 77.6%, respectively. The univariate analyses of all IMA patients demonstrated that 15 CT imaging features, in addition to the clinicopathologic characteristics, significantly correlated with the recurrence or death of IMA patients. The multivariable analysis revealed that five of them, including imaging subtype (p = 0.002), spiculation (p < 0.001), tumor density (p = 0.008), air bronchogram (p < 0.001), emphysema (p < 0.001), and location (p = 0.029) were independent prognostic factors. The subgroup analysis demonstrated that pneumonic-type IMA had a significantly worse prognosis than solitary-type IMA. Moreover, for solitary-type IMAs, the most independent CT imaging biomarkers were air bronchogram and emphysema with an adjusted p value less than 0.05; for pneumonic-type IMA, the tumors with mixed consolidation and ground-glass opacity were associated with a longer DFS (adjusted p = 0.012).

Conclusion

CT imaging features characteristic of IMA may provide prognostic information and individual risk assessment in addition to the recognized clinical predictors.

Fluid-filled Cystic Lesions of the Lungs

A pulmonary cyst usually refers to an air-filled space with a smooth, thin wall. Fluid-filled cystic lesions of the lungs include a range of etiologies such as true cysts, congenital malformations, infections, and benign and malignant neoplasms. With relatively little solid component, these lesions often have similar imaging appearances to one another. This article focuses on key imaging features and clinical characteristics that can be used to narrow the differential diagnosis.

Long noncoding RNA HOXC-AS3 facilitates the progression of invasive mucinous adenocarcinomas of the lung via modulating FUS/FOXM1

Invasive mucinous adenocarcinoma of the lung (IMA), a mucinous variant of lung adenocarcinoma, is strongly linked with a worse prognosis. Therefore, a deeper understanding about its molecular mechanism may conduce to a promising IMA therapy. Long non-coding RNAs (lncRNAs) have recently caught great attention for their crucial roles in diverse diseases regarding tumor initiation and progression. However, the potential role of the lncRNA HOXC-AS3 IMA is not well established. Hence, the purpose of present study is to manifest HOXC-AS3-regulated inner mechanism in IMA development. It revealed that HOXC-AS3 was highly expressed in IMA cells. Additionally, it was identified that the significant down-regulation of HOXC-AS3 obstructed cell proliferation and migration in IMA. As far as mechanism is concerned, it found that HOXC-AS3 recruited FUS to stabilize FOXM1 mRNA, accelerating IMA progression. Taken together, these data suggested that HOXC-AS3 may be recognized as a novel therapeutic target for patients with IMA or at least offer new views for molecular therapy.

Can Quantitative Volumetric Analysis Predict Tumor Recurrence in the Patients with Mucinous Adenocarcinoma of the Lung After Surgical Resection?

RATIONALE AND OBJECTIVES

Mucinous adenocarcinoma (MAC) is a distinct histologic variant subtype of lung adenocarcinomas. However, detailed radiologic findings and prognostic factors are still poorly understood. Thus, this study aimed to investigate the prognostic value of quantitative volumetric analysis of the computed tomography images of patients with MAC after. surgical resection.

MATERIALS AND METHODS

Semiautomatic segmentation from computed tomography images of 60 patients with pathologically confirmed MAC was performed and retrospectively reviewed. The main cutoff value in Hounsfield Units (HU) to predict tumor recurrence was defined by receiver-operating curve analysis. Solid volume of mass (SVM) was defined as the volume of HU greater than this cutoff, and solid ratio (Sratio) was defined as SVM divided by total volume. Each parameter was compared to clinicopathologic characteristics and maximum standardized uptake value. Disease-free survival (DFS) was assessed and was compared among patients. Univariate and multivariate Cox regression was performed to predict DFS of MAC.

RESULTS

The cutoff value of HU as determined by ROC analysis was 20 HU. SVM and Sratio were positively correlated with the maximum standardized uptake and pathologic invasion size, respectively (p < 0.001). SVM and Sratio were significantly higher in the recurrence group than in the no-recurrence group (p < 0.001). Multivariate Cox proportional hazards regression analysis revealed that the SVM (Hazard Ratio 1.016; 95% Confidence Interval 1.000-1.032; p = 0.048) and Sratio (Hazard Ratio 29.136; 95% Confidence Interval 1.419-598.191; p = 0.029) were independent significant predictors of DFS.

CONCLUSION

Quantitative volumetric parameters can predict the prognosis of patients with MAC after surgical resection.

Morphological classification of pre-invasive lesions and early-stage lung adenocarcinoma based on CT images

OBJECTIVE

To retrospectively analyze the computed tomography (CT) features in patients with pre-invasive lesions and early-stage lung adenocarcinoma and to explore the correlation between tumor morphological changes and pathological diagnoses.

MATERIALS AND METHODS

CT morphological characteristics in 2106 patients with pre-invasive (stage 0) and early-stage (stage I) lung adenocarcinoma were analyzed; lesions were confirmed by surgical pathology. Based on the morphological characteristics, the lesions were divided into eight types: I (cotton ball, ground-glass nodules), II (solid fill), III (granular), IV (dendriform), V (bubble-like lucencies), VI (alveolate or honeycomb), VII (scar-like), and VIII (notched or umbilication). The different distributions of eight morphological types in pathological types of the lesions and subtypes of invasive adenocarcinoma were analyzed by chi-squared or Fisher's exact test. Correlation between the percentage of ground-glass opacity in the lesions and pathology types were analyzed by two-tailed Pearson's test.

RESULTS

A negative correlation was observed between the pathological types and proportion of ground-glass component in the lesions (p < 0.001 and r = - 0.583). Significant differences in morphological characteristics among various pathological types of pre-invasive lesions and early lung adenocarcinomas were observed (p < 0.05). Furthermore, among the different pathological subtypes of stage I invasive adenocarcinoma, the differences in their manifestation as morphological types I, II, III, and VI were statistically significant (p < 0.05).

CONCLUSION

The eight types of morphological classification of pre-invasive lesions and early-stage (stage 0 or stage I) lung adenocarcinoma has different pathological bases, and morphological classification may be useful for the diagnosis and differential diagnosis of lung adenocarcinoma.

KEY POINTS

• CT morphological classification of pre-invasive lesions and lung adenocarcinoma is intuitive. • CT morphological classification characterizes morphological changes of the entire lesion. • Different pathological types of lung adenocarcinoma have different morphological features.

Acinar-Predominant Pattern Correlates With Poorer Prognosis in Invasive Mucinous Adenocarcinoma of the Lung

OBJECTIVES

Invasive mucinous adenocarcinoma (IMA) is a variant of lung adenocarcinoma with several growth patterns, such as lepidic acinar and papillary. However, to our knowledge, no study regarding prognostic and clinicopathologic aspects of IMAs with different growth patterns has been reported.

METHODS

Of 2,236 patients with primary lung adenocarcinoma, 16 were identified as having lepidic-predominant IMA and 10 as having acinar-predominant IMA. Data regarding the clinicopathologic characteristics, computed tomography (CT) features, and prognosis were collected.

RESULTS

No statistically significant difference was noted in sex, age, smoker proportion, and T classification between both groups. The proportion of lymph node metastasis was significantly higher in acinar-predominant IMA (P = .046). Both groups shared many signs in CT findings. Air bronchogram was a relatively specific sign for lepidic-predominant IMA. Survival analysis showed that acinar-predominant IMA had a poorer prognosis (P = .0294).

CONCLUSIONS

Lepidic-predominant and acinar-predominant IMA are two different subtypes of IMA. Acinar-predominant IMA is associated with lymph node metastasis and a poorer prognosis.

PET Scan Contribution in Chest Tumor Management: A Systematic Review for Thoracic Surgeons

Aims and background

In the 90s, the introduction of positron emission tomography (PET) represented a milestone in the staging of thoracic tumors. In the last 10 years, PET scan has been widely adopted in thoracic oncology, showing high accuracy in diagnosis and staging and with promising issues in defining prognosis. The aim of this systematic review was to focus on the results and pitfalls of PET scan use in the modern management of chest tumors.

Methods and study design.

The literature search was performed on May 2010 in PubMed, Embase, and Cochrane according to PRISMA protocol. The search was restricted to publications in English, using in the same string the word “PET” with 9 different chest tumors; results were then filtered by eliminating technical articles, focusing only on papers in which surgery was considered as a potential diagnostic or therapeutic tool. From 6600 papers initially selected, 99 manuscripts were fully analyzed.

Results

Glucose uptake is a metabolic marker useful in the diagnosis and staging of chest tumors. In lung cancer screening, standard uptake value is helpful in defining the risk of malignancy of isolated pulmonary nodules. The addition of PET scan to conventional staging increases detection of nodal and distant metastases in lung cancer, esophageal cancer and malignant mesothelioma. In thymoma, a close relationship between standard uptake value, histology, and Masaoka stage has been advocated. This link between glucose uptake and prognosis suggests that PET translates biological tumor behavior into clinically detectable findings.

Conclusions

PET scan has a crucial role in thoracic oncology due to its impact on diagnosis, staging and prognosis. PET scan expresses the biological behavior of tumors, opening interesting perspectives in chest tumor management and improving detection and stage grouping in lung cancer. It anticipates the diagnosis in long-incubating diseases such as mesothelioma and increases biological knowledge of rare diseases, such as thymoma and other mediastinal tumors.

Radiomic analysis of pulmonary ground-glass opacity nodules for distinction of preinvasive lesions, invasive pulmonary adenocarcinoma and minimally invasive adenocarcinoma based on quantitative texture analysis of CT

Objective

To identify the differences among preinvasive lesions, minimally invasive adenocarcinomas (MIAs) and invasive pulmonary adenocarcinomas (IPAs) based on radiomic feature analysis with computed tomography (CT).

Methods

A total of 109 patients with ground-glass opacity lesions (GGOs) in the lungs determined by CT examinations were enrolled, all of whom had received a pathologic diagnosis. After the manual delineation and segmentation of the GGOs as regions of interest (ROIs), the patients were subdivided into three groups based on pathologic analyses: the preinvasive lesions (including atypical adenomatous hyperplasia and adenocarcinoma in situ) subgroup, the MIA subgroup and the IPA subgroup. Next, we obtained the texture features of the GGOs. The data analysis was aimed at finding both the differences between each pair of the groups and predictors to distinguish any two pathologic subtypes using logistic regression. Finally, a receiver operating characteristic (ROC) curve was applied to accurately evaluate the performances of the regression models.

Results

We found that the voxel count feature (P<0.001) could be used as a predictor for distinguishing IPAs from preinvasive lesions. However, the surface area feature (P=0.040) and the extruded surface area feature (P=0.013) could be predictors of IPAs compared with MIAs. In addition, the correlation feature (P=0.046) could distinguish preinvasive lesions from MIAs better.

Conclusions

Preinvasive lesions, MIAs and IPAs can be discriminated based on texture features within CT images, although the three diseases could all appear as GGOs on CT images. The diagnoses of these three diseases are very important for clinical surgery.

Solitary ground-glass opacity nodules of stage IA pulmonary adenocarcinoma: combination of 18F-FDG PET/CT and high-resolution computed tomography features to predict invasive adenocarcinoma

To investigate the performance of combined 18F-FDG Positron Emission Tomography/Computed Tomography with high-resolution CT for differentiating invasive adenocarcinoma from adenocarcinoma in situ (pre-invasive lesion) or minimally invasive adenocarcinoma in stage IA lung cancer patients with solitary ground-glass opacity nodules. This retrospective study enrolled 58 consecutive stage IA pulmonary adenocarcinoma patients with solitary ground-glass opacity nodules. The characteristics and measurements of the ground-glass opacity nodules as pure ground-glass opacity nodules and mixed ground-glass opacity nodules in the pre-invasive or minimally invasive adenocarcinoma and invasive adenocarcinoma groups on Positron Emission Tomography/Computed Tomography and high-resolution CT were compared and analyzed. Ground-glass opacity nodules in the pre-invasive or minimally invasive adenocarcinoma group preferentially manifested as pure ground-glass opacity nodule (p < 0.01) compared to the invasive adenocarcinoma group. While cystic appearance was more common in the invasive adenocarcinoma group (p < 0.05). Significant differences were found in the diameter of the ground-glass opacity nodule itself and its solid component, and consolidation/tumor ratio between the two groups. The sensitivity in predicting invasive adenocarcinoma was higher with a combined consolidation/tumor ratio > 0.38 and SUV_max > 1.46 in mixed ground-glass opacity nodule when compared to those of SUV_max > 0.95 alone or consolidation/tumor ratio> 0.39 alone (both p > 0.05). For a mixed ground-glass opacity nodule combined consolidation/tumor ratio > 0.38 and SUV_max > 1.46 appears to better predict invasive adenocarcinoma in stage IA lung cancer patients with solitary ground-glass opacity nodules.

Are There Any Additional Benefits to Performing Positron Emission Tomography/Computed Tomography Scans and Brain Magnetic Resonance Imaging on Patients with Ground-Glass Nodules Prior to Surgery?

Background

A ground-glass nodule (GGN) represents early-stage lung adenocarcinoma. However, there is still no consensus for preoperative staging of GGNs. Therefore, we evaluated the need for the routine use of positron emission tomography/computed tomography (PET)/computed tomography (CT) scans and brain magnetic resonance imaging (MRI) during staging.

Methods

A retrospective analysis was undertaken in 72 patients with 74 GGNs of less than 3 cm in diameter, which were confirmed via surgery as malignancy, at the Samsung Medical Center between May 2010 and December 2011.

Results

The median age of the patients was 59 years. The median GGN diameter was 18 mm. Pure and part-solid GGNs were identified in 35 (47.3%) and 39 (52.7%) cases, respectively. No mediastinal or distant metastasis was observed in these patients. In preoperative staging, all of the 74 GGNs were categorized as stage IA via chest CT scans. Additional PET/CT scans and brain MRIs classified 71 GGNs as stage IA, one as stage IIIA, and two as stage IV. However, surgery and additional diagnostic work-ups for abnormal findings from PET/CT scans classified 70 GGNs as stage IA, three as stage IB, and one as stage IIA. The chest CT scans did not differ from the combined modality of PET/CT scans and brain MRIs for the determination of the overall stage (94.6% vs. 90.5%; kappa value, 0.712).

Conclusion

PET/CT scans in combination with brain MRIs have no additional benefit for the staging of patients with GGN lung adenocarcinoma before surgery.

Pulmonary ground-glass opacity: computed tomography features, histopathology and molecular pathology

The incidence of pulmonary ground-glass opacity (GGO) lesions is increasing as a result of the widespread use of multislice spiral computed tomography (CT) and the low-dose CT screening for lung cancer detection. Besides benign lesions, GGOs can be a specific type of lung adenocarcinomas or their preinvasive lesions. Evaluation of pulmonary GGO and investigation of the correlation between CT imaging features and lung adenocarcinoma subtypes or driver genes can be helpful in confirming the diagnosis and in guiding the clinical management. Our review focuses on the pathologic characteristics of GGO detected at CT, involving histopathology and molecular pathology.

Clinicopathological and immunohistochemical features of lung invasive mucinous adenocarcinoma based on computed tomography findings

Background

We performed an analysis to clarify differences in clinicopathological and molecular features of lung invasive mucinous adenocarcinoma (IMA) based on computed tomography (CT) findings and their impact on prognosis.

Patients and methods

On the basis of CT findings, we divided lung IMA into three subtypes: solid, bubbling, and pneumonic. We then investigated differences in clinicopathological characteristics, prognosis, and the expressions of well-identified biomarkers, including cyclooxygenase-2 (Cox-2), excision repair cross-complementation group 1 (ERCC1), ribonucleotide reductase M1 (RRM1), class III beta-tubulin, thymidylate synthase (TS), secreted protein acidic and rich in cysteine (SPARC), programmed cell death-1 ligand-1 (PD-L1), and epidermal growth factor receptor mutation, among the three subtypes.

Results

A total of 29 patients with resected lung IMA were analyzed. Compared with the solid or bubbling type, the pneumonic type had a higher proportion of symptoms, a larger tumor size, a higher pathological stage, and a significantly worse prognosis. The immunohistochemical findings tended to show high expression of RRM1, class III beta-tubulin, and Cox-2 in the tumor and of SPARC in the stroma, but not of ERCC1, TS, and PD-L1 in the tumor. None of the biomarkers with high expression levels in the tumor were prognostic biomarkers, but the expression of SPARC in the stroma was correlated with a poor outcome.

Conclusion

Clinical and pathological features, in conjunction with molecular data, indicate that IMA should be divided into different subgroups. In our results, the pneumonic type was correlated with a significantly worse outcome. Further studies should be performed to confirm our conclusion and to explore its molecular implications.

HRCT features of surgically resected invasive mucinous adenocarcinoma associated with interstitial pneumonia

BACKGROUND AND OBJECTIVE

Lung cancer is prevalent among patients with interstitial pneumonia (IP). HRCT findings mucinous adenocarcinoma in patients with IP have not been described.

METHODS

In 112 consecutive patients with 120 surgically resected IP-associated lung cancers, 42 patients had pathologically proven invasive adenocarcinoma (IA). A total of 14 out of 42 patients (10 men, 4 women, mean age, 68.4 years) had invasive mucinous adenocarcinoma. We reviewed the patients' medical records and HRCT scans.

RESULTS

Invasive mucinous adenocarcinoma were most commonly associated with idiopathic IP (n = 13) affecting the lower lobe adjacent to a fibrocystic changes. In 11 patients with invasive mucinous adenocarcinoma or other types of IA, the tumour was adjacent to a fibrocystic lesion. In invasive mucinous adenocarcinoma, malignant signs included lobulation (n = 11), spiculation (n = 9), vascular convergence (n = 10) and pleural indentation (n = 2). Characteristic findings of mucinous adenocarcinoma (i.e. vague margins (n = 10), lobular-bounded margins (n = 11), air bronchogram (n = 11) and bubble-like low attenuation (n = 8)) were more common in invasive mucinous adenocarcinoma than in other IA types. All invasive mucinous adenocarcinoma tumours (n = 11) were closely associated with fibrosis.

CONCLUSION

Mixed ground-glass opacity and consolidation adjacent to a fibrocystic lesion with malignant signs and characteristic features of mucinous adenocarcinoma indicate malignancy.

Clinical course of stage IV invasive mucinous adenocarcinoma of the lung

INTRODUCTION

An invasive mucinous adenocarcinoma (IMA) is a distinct lung adenocarcinoma variant. The characteristics of stage IV IMAs are relatively unclear since most previous studies described resected cases from stage I to III. The present study aimed to investigate the clinical course of stage IV IMAs and compare the findings to those of stage IV invasive non-mucinous adenocarcinomas (INMAs).

METHODS

The study included 36 IMA patients and 210 INMA patients. The clinicopathological parameters, treatment methods and responses, overall survival (OS), and progression-free survival (PFS) were evaluated.

RESULTS

IMAs were predominantly located in the lower lobes and frequently presented with multifocal consolidation and lung-to-lung or pleural metastasis. KRAS mutations were noted in 60.0% of the examined IMAs. Non-TKI chemotherapy (CTx) was used in 72.2% of the IMA patients. OS was significantly better in untreated IMA patients than in untreated INMA patients. IMA patients treated with non-TKI CTx had no improvement of OS compared to the untreated IMA patients. However, among INMA patients, OS was best with TKIs in patients harbouring targetable mutations, followed by non-TKI CTx. IMA and INMA patients treated with non-TKI CTx had similar PFS.

CONCLUSIONS

Stage IV IMAs have distinct clinicopathological characteristics, and they might be less aggressive than INMAs. Since non-TKI CTx might not be beneficial in IMA patients, new therapeutic approach is necessary.

Prognosis in Resected Invasive Mucinous Adenocarcinomas of the Lung: Related Factors and Comparison with Resected Nonmucinous Adenocarcinomas

INTRODUCTION

In the 2015 World Health Organization classification, invasive mucinous adenocarcinoma (IMA) is categorized as one of various subtypes of lung invasive adenocarcinoma (ADC). However, no comprehensive analysis regarding the clinicoradiologic and prognostic features of IMA has been reported. We aimed to report prognostic factors in IMA and to compare the prognosis of IMAs with that of nonmucinous ADCs.

METHODS

We included 81 patients with a solitary IMA of the lung and analyzed them from the standpoint of clinicoradiologic presentation. Survival rates were assessed and compared with those of 646 resected solitary invasive nonmucinous ADCs.

RESULTS

Patients with IMA showed longer disease-free survival (DFS) than did those with nonmucinous ADCs, whereas overall survival (OS) did not differ significantly (p = 0.023 and p = 0.824, respectively). The DFS of patients with IMA was between that of patients with lepidic predominant (low-grade) and acinar/papillary predominant (intermediate-grade) ADC. In terms of OS, the survival curve of IMA was similar to that of acinar/papillary predominant ADC. Multivariate analysis revealed that tumor size (hazard ratio [HR] = 1.370, 95% confidence interval [CI]: 1.141-1.645, p = 0.001) and maximum standardized uptake value (HR = 1.338, 95% CI: 1.160-1.544, p < 0.001) were independent poor prognostic predictors for DFS. Regarding OS, tumor size (HR = 1.309, 95% CI: 1.092-1.570; p = 0.004) was the only predictor of poor prognosis.

CONCLUSION

Patients with IMA demonstrate a DFS between that of patients with low-grade nonmucinous ADC and that of patients with intermediate-grade nonmucinous ADC and an OS similar to that of patients with intermediate-grade nonmucinous ADC. In IMA, tumor size and maximum standardized uptake value are the factors related to mitigating DFS and tumor size is the only predictor for reduced OS.

Improvement in imaging diagnosis technique and modalities for solitary pulmonary nodules: from ground-glass opacity nodules to part-solid and solid nodules

With advances in CT technology and the popularity of low-dose CT as a device for lung cancer screening, the detection rate of sub-solid pulmonary nodules as well as solid nodules has been increased. Distinguishing solid from sub-solid features is an essential step in the CT evaluation of solitary pulmonary nodules (SPNs) because strategies for nodule characterization and guidelines for management are different for each category. In addition to conventional CT parameters, numerous novel concepts and modalities have been developed. Although there is currently no single effective method for differentiating malignant from benign nodules, growth rate measurement using volumetry, evaluation of tumor vascularity on dynamic helical CT, dual-energy CT and MRI and physiologic evaluation with PET/CT can all be useful for nodule characterization. New techniques such as tomosynthesis can improve detection over radiography alone. The purpose of this article is to enhance our understanding of the evidence-based strategies involved in diagnosing SPNs.

How should we manage small focal pure ground-glass opacity nodules on high-resolution computed tomography? A single institute experience

BACKGROUND

Although the detection of pure ground-glass opacity (p-GGO) nodules on high-resolution chest computed tomography (HRCT) often implies a diagnosis of lung adenocarcinoma, the management of p-GGO nodules remains under discussion.

OBJECTIVE

To assess the correlation between the radiological and pathological diagnoses of small p-GGO on HRCT.

PATIENTS AND METHODS

This is a single-institution retrospective study. We analyzed 89 consecutive patients, including 33 patients with resected p-GGO nodule(s) equal or less than 20 mm in maximal diameter on axial images of HRCT.

RESULTS

Thirty-nine patients underwent locoregional treatment (Treatment group), including surgical resection in 33 and stereotactic body radiation therapy in six. The remaining 50 patients were observed (Observation group) using periodic chest HRCT. The median follow-up time was 30.4 (4.9-102.5) months in the Treatment group and 44.8 (0.4-1125.8) months in the Observation group. During the follow-up period, the p-GGO nodules increased in size in eight patients over a median of 20.6 (12.1-50.6) months, with increased attenuation in three patients over a median of 20.6 (12.1-50.6) months, and either decreased in size or disappeared in four patients over a median of 6.9 (2.0-11.2) months. Thirty-three patients with 47 nodules underwent surgical resection, including 41 adenocarcinomas, one neuroendocrine tumor, three cases of atypical adenomatous hyperplasia and two benign lesions. The frequency of invasive adenocarcinoma was higher among the larger p-GGO nodules.

CONCLUSIONS

Careful observation and decision making with respect to the timing of intervention in cases of p-GGO nodules are warranted.

Adenocarcinoma with BAC features presented as the nonsolid nodule is prone to be false-negative on 18F-FDG PET/CT

Purpose. The present study investigated which type of adenocarcinoma with BAC features was prone to be false-negative on 18F-FDG PET/CT. Materials and Methods. A retrospective study was performed on 51 consecutive patients with localized adenocarcinoma with BAC features. CT and PET were assessed for lesion size, GGO percentage, and SUVmax. Lesions with FDG uptake the same as or more than mediastinal blood-pool activity were considered as PET-positive. Results. Of the 51 cases, 19.6% presented as pure GGO nodules, 31.4% as mixed nodules, and 49.0% as solid nodules. None of the pure GGO nodules was 18F-FDG avid, compared with 37.5% of mixed nodules and 96.0% of solid nodules (χ² = 31.55, P = 0.000). In the mixed nodule group, SUVmax was negatively correlated with GGO percentage (r = −0.588; P = 0.021). The positive detection rate of 18F-FDG PET/CT was 50.0%, 55.6%, and 100% in tumors 1.1–2.0 cm, 2.1–3.0 cm, and >3.0 cm in diameter, respectively (χ² = 5.815, P = 0.055). General linear model factor analysis showed that the GGO was an important factor contributing to false-negative PET/CT results (F = 23.992, P = 0.000), but lesion size was not (F = 0.602, P = 0.866). Conclusions. The present study indicated that the adenocarcinoma with BAC features presented as nonsolid nodule is prone to be false negative on 18F-FDG PET/CT.

Relation between thin-section computed tomography and clinical findings of mucinous adenocarcinoma

BACKGROUND

Detailed reports on mucinous adenocarcinoma (formerly "mucinous bronchioloalveolar carcinoma") have not been published. We evaluated the correlation between thin-section computed tomography findings and the clinicopathologic characteristics and prognosis of mucinous adenocarcinoma.

METHODS

From April 1997 to March 2008, 45 resected lung carcinomas were diagnosed as mucinous adenocarcinoma. Five cases of multiple lung cancers or ambiguous mucinous adenocarcinoma were excluded. Tumors were classified as "solitary-type" or "pneumonic-type" tumors according to the thin-section computed tomography findings. We evaluated the clinicopathologic characteristics and the epidermal growth factor receptor and KRAS gene mutation statuses and correlated the thin-section computed tomography findings with patient prognoses.

RESULTS

Thirty patients had solitary-type and 10 had pneumonic-type tumors. The lesions in 23, 14, and 3 patients were classified as pathologic stage I, stage II, and stage III, respectively. Five patients had adenocarcinoma in situ, 9 had minimally invasive adenocarcinoma, and 26 had invasive mucinous adenocarcinoma. Thirteen patients showed recurrences, which were classified as intrapulmonary metastases in all patients. The 5-year overall and relapse-free survival rates were 83.3% and 88.8%, respectively, in patients with solitary-type tumors and 20.0% and 0%, respectively, in patients with pneumonic-type tumors (p < 0.001). The median follow-up time for surviving patients was 81 months. KRAS mutations were detected in 30 patients, but epidermal growth factor receptor mutations were absent in all patients.

CONCLUSIONS

Our results indicated that thin-section computed tomography findings for mucinous adenocarcinoma were useful in predicting prognosis before surgical resection. Further studies are required to improve the treatment strategy for mucinous adenocarcinoma.

The revised lung adenocarcinoma classification-an imaging guide

Advances in our understanding of the pathology, radiology and clinical behaviour of peripheral lung adenocarcinomas facilitated a more robust terminology and classification of these lesions. The International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) classification introduced new terminology to better reflect this heterogeneous group of adenocarcinomas formerly known as bronchoalveolar cell carcinoma (BAC). There is now a clear distinction between pre-invasive, minimally invasive and frankly invasive lesions. The radiographic appearance of these ranges from pure ground glass nodules to solid mass lesions. Radiologists must be aware of the new classification in order to work alongside multidisciplinary colleagues to allow accurate staging and treatment. This article reviews the new classification of lung adenocarcinomas. Management options of these lesions with particular focus on radiological implications of the new classification will be reviewed.

Pulmonary adenocarcinoma: implications of the recent advances in molecular biology, treatment and the IASLC/ATS/ERS classification

A decade ago, lung cancer could conveniently be classified into two broad categories-either the small cell lung carcinoma (SCLC), or the non-small cell lung carcinoma (NSCLC), mainly to assist in further treatment related decision making. However, the understanding regarding the eligibility of adenocarcinoma histology for treatments with agents such as pemetrexed and bevacizumab made it a necessity for NSCLC to be classified into more specific sub-groups. Then, the availability of molecular targeted therapy with oral tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib not only further emphasized the need for accurate sub-classification of lung cancer, but also heralded the important role of molecular profiling of lung adenocarcinomas. Given the remarkable advances in molecular biology, oncology and radiology, a need for felt for a revised classification for lung adenocarcinoma, since the existing World Health Organization (WHO) classification of lung cancer, published in the year 2004 was mainly a pathological system of classification. Thus, there was a combined effort by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS) and the European Respiratory Society (ERS) with an effort to inculcate newly established perspectives from clinical, molecular and radiological aspects in evolving a modern classification for lung adenocarcinomas. This review provides a summary of the recent advances in molecular biology and molecular targeted therapy with respect to lung adenocarcinoma. Also, a brief summation of the salient recommendations provided in the IASLC/ATS/ERS classification of lung adenocarcinomas is provided. Lastly, a discussion regarding the future prospects with lung adenocarcinoma is included.

Characteristics and management strategies for the incidental pulmonary nodule

SUMMARY: 

Pulmonary nodules are frequent, unanticipated findings on imaging studies obtained for other purposes across all areas of medical practice. As nodule detection raises concern for malignancy, evaluation and follow-up of an incidental nodule is imperative. Clinicians are charged with counseling patients and directing further evaluation amid uncertainty and anxiety. The goals of follow-up and management are to identify malignant lesions at an early stage, while avoiding unnecessary procedures and potential harm to patients with benign nodules. In this review, we aim to outline the clinical and radiographic characteristics that can aid in likelihood stratification, to identify gaps in our current knowledge, and to present a logical approach to nodule management, based on the available evidence.

The impact of intracytoplasmic mucin in lung adenocarcinoma with pneumonic radiological presentation

OBJECTIVES

This study investigated the clinical and prognostic impact of intracytoplasmic mucin in lung adenocarcinoma with "pneumonic" radiological presentation, formerly known as bronchioloalveolar carcinoma (BAC).

PATIENTS AND METHODS

Between 1986 and 2011, clinical and pathological data from 120 consecutive patients with lung adenocarcinoma with "pneumonic" radiological presentation were reviewed. Intracytoplasmic mucin was assessed using a diastase-resistant periodic acid-Schiff staining. The presence of EGFR or K-Ras mutations and ALK rearrangement were determined in surgical samples.

RESULTS

The two predominant histological patterns were invasive mucinous adenocarcinoma (40%) and lepidic predominant adenocarcinoma (32%). Intracytoplasmic mucin was detected in 71 patients (59.2%) who were more likely to be non-smokers (p=0.04) and have bronchorrhea (p=0.006), crepitant rales (p=0.02), or neutrophil alveolitis (p=0.0004). In mucin-producing tumors, EGFR mutation was not detected, K-Ras mutations and ALK rearrangement were present in 32% and 3% of cases, respectively. In non-mucin-producing tumors, EGFR and K-Ras mutations were detected in 17% and 10% of cases, respectively, no ALK rearrangement was detected. In univariate analysis, performance status>0, crepitant rales, bronchorrhea, neutrophil alveolitis, bilateral extension, intracytoplasmic mucin and no surgery were associated with worse survival. In multivariate analyses, intracytoplasmic mucin, neutrophil alveolitis, and no surgery were independent factors for worse survival.

CONCLUSION

Intracytoplasmic mucin is associated with specific clinical characteristics and is an independent factor for worse survival in lung adenocarcinoma formerly known as BAC.

Nodule characterization: subsolid nodules

In this review, we focus on the radiologic, clinical, and pathologic aspects primarily of solitary subsolid pulmonary nodules. Particular emphasis will be placed on the pathologic classification and correlative computed tomography (CT) features of adenocarcinoma of the lung. The capabilities of fluorodeoxyglucose positron emission tomography-CT and histologic sampling techniques, including CT-guided biopsy, endoscopic-guided biopsy, and surgical resection, are discussed. Finally, recently proposed management guidelines by the Fleischner Society and the American College of Chest Physicians are reviewed.

IASLC/ATS/ERS International Multidisciplinary Classification of Lung Adenocarcinoma: novel concepts and radiologic implications

In 2011, the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society proposed a new classification for lung adenocarcinoma that included a number of changes to previous classifications. This classification now considers resection specimens, small biopsies, and cytology specimens. Two former histopathologic terms, bronchioloalveolar carcinoma and mixed subtype adenocarcinoma, are no longer to be used. For resection specimens, the new terms of adenocarcinoma in situ and minimally invasive adenocarcinoma are introduced for small adenocarcinomas showing pure lepidic growth and predominantly lepidic growth, with invasion ≤5 mm, respectively. Invasive adenocarcinomas are now classified by their predominant pattern as lepidic, acinar, papillary, and solid; a micropapillary pattern is newly added. This classification also provides guidance for small biopsies and cytology specimens. For adenocarcinomas that include both an invasive and a lepidic component, it is suggested that for T staging the size of the T-factor may be best measured on the basis of the size of the invasive component rather than on the total size of tumors including lepidic components, both on pathologic and computed tomography assessment. This suggestion awaits confirmation in clinical-radiologic trials. An implication for M staging is that comprehensive histologic subtyping along with other histologic and molecular features can be very helpful in determining whether multiple pulmonary nodules are separate primaries or intrapulmonary metastases. In this review article, we provide an illustrated overview of the proposed new classification for lung adenocarcinoma with an emphasis upon what the radiologist needs to know in order to successfully contribute to the multidisciplinary strategic management of patients with this common histologic subtype of lung cancer.

Diagnosis of lung adenocarcinoma in resected specimens: implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification

A new lung adenocarcinoma classification has been published by the International Association for the Study of Lung Cancer, the American Thoracic Society, and the European Respiratory Society. This new classification is needed to provide uniform terminology and diagnostic criteria, most especially for bronchioloalveolar carcinoma. It was developed by an international core panel of experts representing all 3 societies with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons.This summary focuses on the aspects of this classification that address resection specimens. The terms bronchioloalveolar carcinoma and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced, such as adenocarcinoma in situ and minimally invasive adenocarcinoma for small solitary adenocarcinomas with either pure lepidic growth (adenocarcinoma in situ) and predominant lepidic growth with invasion of 5 mm or less (minimally invasive adenocarcinoma), to define the condition of patients who will have 100% or near 100% disease-specific survival, respectively, if they undergo complete lesion resection. Adenocarcinoma in situ and minimally invasive adenocarcinoma are usually nonmucinous, but rarely may be mucinous. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous bronchioloalveolar carcinoma), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous bronchioloalveolar carcinoma), colloid, fetal, and enteric adenocarcinoma.It is possible that this classification may impact the next revision of the TNM staging classification, with adjustment of the size T factor according to only the invasive component pathologically in adenocarcinomas with lepidic areas.

Clinical importance of [18F]fluorodeoxyglucose positron emission tomography/computed tomography in the management of patients with bronchoalveolar carcinoma: Role in the detection of recurrence

[¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been reported to have a low sensitivity in the initial diagnosis of bronchoalveolar carcinoma (BAC) due to BAC’s low metabolic activity. The aim of this study was to assess the value of [¹⁸F]FDG-PET/CT in the detection of BAC recurrence. Between February 2007 and September 2011, the [¹⁸F]FDG-PET/CT scans that were performed on patients with known, histologically proven BAC were studied. A total of 24 [¹⁸F]FDG-PET/CT scans were performed in 22 patients, including 16 males and 6 females, with a mean age of 65±9 years. Among the scans, 15 were performed to assess for possible recurrence with equivocal findings in conventional imaging methods and 9 for restaging post-therapy. In all cases conventional imaging studies (CT and MRI) were performed 5–30 days prior to PET/CT. Among the 24 [¹⁸F]FDG-PET/CT scans, 18 were positive and 6 negative. Among the 15 [¹⁸F]FDG-PET/CT scans performed for suspected recurrence, 34 lesions were detected and the mean maximum standardized uptake value (SUVmax) was 6.8±3.26. In nine scans, upstaging was observed, while two were in agreement with the findings of the conventional modalities. A greater number of lesions were detected in two scans and fewer lesions were detected in one, with no change in staging. Only one scan was negative. By contrast, in patients examined for restaging, there were only five lesions with a mean SUVmax of 4.86±3.18. Agreement between the findings of [¹⁸F]FDG-PET/CT and the conventional modalities was observed in 8 out of 9 cases. Although [¹⁸F]FDG-PET/CT has been reported to have a low sensitivity in the initial diagnosis of BAC, the present results indicate that when there is recurrence, the lesions become [¹⁸F]FDG avid. [¹⁸F]FDG-PET/CT may provide further information in patients evaluated for recurrence and thus improve patient management.

Pulmonary mucinous cystadenocarcinoma: report a case and review of CT findings

A pulmonary mucinous cystadenocarcinoma is an extremely rare tumor that is considered to be a cystic variant of mucin-producing lung adenocarcinoma. We present a case of pulmonary mucinous cystadenocarcinoma in a 54-year-old woman. Chest CT scans showed a 4.3-cm-sized, lobulated, well-defined, and homogeneous mass in the right middle lobe with peripheral stippled calcifications that demonstrated low-attenuation with no enhancement after contrast administration; ¹⁸F-fluorodeoxyglucose (FDG) PET/CT demonstrated mild heterogeneous FDG uptake. The mass was diagnosed as adenocarcinoma with mucin production by transbronchial lung biopsy. Right middle lobectomy was performed, and the pathologic examination disclosed a pulmonary mucinous cystadenocarcinoma.

New pathologic classification of lung cancer: relevance for clinical practice and clinical trials

We summarize significant changes in pathologic classification of lung cancer resulting from the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) lung adenocarcinoma classification. The classification was developed by an international core panel of experts representing IASLC, ATS, and ERS with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. Because 70% of patients with lung cancer present with advanced stages, a new approach to small biopsies and cytology with specific terminology and criteria focused on the need for distinguishing squamous cell carcinoma from adenocarcinoma and on molecular testing for EGFR mutations and ALK rearrangement. Tumors previously classified as non-small-cell carcinoma, not otherwise specified, because of the lack of clear squamous or adenocarcinoma morphology should be classified further by using a limited immunohistochemical workup to preserve tissue for molecular testing. The terms "bronchioloalveolar carcinoma" and "mixed subtype adenocarcinoma" have been discontinued. For resected adenocarcinomas, new concepts of adenocarcinoma in situ and minimally invasive adenocarcinoma define patients who, if they undergo complete resection, will have 100% disease-free survival. Invasive adenocarcinomas are now classified by predominant pattern after using comprehensive histologic subtyping with lepidic, acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype with poor prognosis. Former mucinous bronchioloalveolar carcinomas are now called "invasive mucinous adenocarcinoma." Because the lung cancer field is now rapidly evolving with new advances occurring on a frequent basis, particularly in the molecular arena, this classification provides a much needed standard for pathologic diagnosis not only for patient care but also for clinical trials and TNM classification.

Recommendations for the management of subsolid pulmonary nodules detected at CT: a statement from the Fleischner Society

This report is to complement the original Fleischner Society recommendations for incidentally detected solid nodules by proposing a set of recommendations specifically aimed at subsolid nodules. The development of a standardized approach to the interpretation and management of subsolid nodules remains critically important given that peripheral adenocarcinomas represent the most common type of lung cancer, with evidence of increasing frequency. Following an initial consideration of appropriate terminology to describe subsolid nodules and a brief review of the new classification system for peripheral lung adenocarcinomas sponsored by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS), six specific recommendations were made, three with regard to solitary subsolid nodules and three with regard to multiple subsolid nodules. Each recommendation is followed first by the rationales underlying the recommendation and then by specific pertinent remarks. Finally, issues for which future research is needed are discussed. The recommendations are the result of careful review of the literature now available regarding subsolid nodules. Given the complexity of these lesions, the current recommendations are more varied than the original Fleischner Society guidelines for solid nodules. It cannot be overemphasized that these guidelines must be interpreted in light of an individual's clinical history. Given the frequency with which subsolid nodules are encountered in daily clinical practice, and notwithstanding continuing controversy on many of these issues, it is anticipated that further refinements and modifications to these recommendations will be forthcoming as information continues to emerge from ongoing research.

Radiologic implications of the 2011 classification of adenocarcinoma of the lung

Now the leading subtype of lung cancer, adenocarcinoma received a new classification in 2011. For tumors categorized previously as bronchioloalveolar carcinoma (BAC), criteria and terminology had not been uniform, so the 2011 classification provided four new terms: (a) adenocarcinoma in situ (AIS), representing histopathologically a small (≤3-cm), noninvasive lepidic growth, which at computed tomography (CT) is usually nonsolid; (b) minimally invasive adenocarcinoma, representing histopathologically a small (≤3-cm) and predominantly lepidic growth that has 5-mm or smaller invasion, which at CT is mainly nonsolid but may have a central solid component of up to approximately 5 mm; (c) lepidic predominant nonmucinous adenocarcinoma, representing histopathologically invasive adenocarcinoma that shows predominantly lepidic nonmucinous growth, which at CT is usually part solid but may be nonsolid or occasionally have cystic components; and (d) invasive mucinous adenocarcinoma, histopathologically showing lepidic growth as its predominant component, which at CT varies widely from solid to mostly solid to part solid to nonsolid and may be single or multiple (when multifocal, it was formerly called multicentric BAC). In addition, new histopathologic subcategories of acinar, papillary, micropapillary, and solid predominant adenocarcinoma are now described, all as nonmucinous, predominantly invasive, may include a small lepidic component, and at CT are usually solid but may include a small nonsolid component. The micropapillary subtype has a poorer prognosis than the other subtypes. In addition, molecular genetic correlations for the subcategories of adenocarcinoma of the lung are now a topic of increasing interest. As the new classification enters common use, further descriptions of related correlations can be anticipated.