Reversible dementia due to vitamin B12 deficiency in a lung cancer patient: Relevance of preoperative evaluation.

OBJECTIVE: Cognitive dysfunction has a negative effect on cancer treatment; however, in a cancer setting, specific treatments can restore cognitive function. Such conditions are known as reversible dementia, with one of these being vitamin B12 (VB12) deficiency. However, there have been no reports of VB12 deficiency identified by preoperative evaluation in cancer patients. METHOD: We studied a patient who was referred to the Department of Psycho-oncology on suspicion of cognitive decline prior to lung cancer surgery. Preoperative evaluation revealed VB12 deficiency. RESULTS: The patient was an 82-year-old woman diagnosed with lung cancer. She also presented with cognitive decline and, therefore, was referred to the Department of Psycho-oncology for preoperative evaluation. The patient scored 19 points on a Mini-Mental State Examination (MMSE), which is indicative of cognitive decline. As the onset of symptoms occurred several months previously and they were subacute, the possibility of reversible dementia was considered. Extensive examination revealed VB12 deficiency, and VB12 replacement therapy normalized the MMSE score to 25 points before surgery. SIGNIFICANCE OF THE RESULTS: When cognitive decline is observed in cancer patients, it is necessary to actively evaluate the serum levels of some B vitamins, including VB12.

[Surgical Outcome of Sublobar Resection in High-risk Patients with Non-small Cell Lung Cancer].

OBJECTIVES: Pulmonary lobectomy is the standard surgical procedure for resectable non-small cell lung cancer (NSCLC), while sublobar resection is an important surgical alternative for high-risk patients with comorbidities. We evaluated the treatment outcome and prognostic factors of sublobar resection in high-risk patients with NSCLC. METHODS: Eighty three high-risk patients who underwent compromised sublobar resection for clinical-N0 NSCLC with a solid appearance were retrospectively reviewed. A total of 47 wedge resections and 36 segmentectomies performed. RESULTS: Poor pulmonary function and synchronous or metachronous multiple lung cancer were found in 56.7% and 20.5% of patients respectively, all requiring sublobar resection. There were 21 instances of tumor recurrence and 24 deaths during a mean follow-up of 1,500 days. There was no local recurrence in the segmentectomy group. The 3-year recurrence free survival (RFS) and overall survival (OS) were 72.6% and 73.8% respectively. A multivariate analysis indicated that resection type and lymphatic invasion were independent prognostic factors for RFS. In the wedge resection group, a ratio of surgical margin to clinical tumor size greater than 1 (MT ratio≥1) was an independent prognostic factor for RFS( 87.1%,p=0.001). CONCLUSION: Segmentectomy leads to a favorable prognosis. MT ratio was independently associated with a longer RFS in the wedge resection group.

[Tumors of the diaphragm, diagnosis and surgical treatment].

Primary tumors of the diaphragm are very rare, and we often have difficulties in preoperative diagnosis and accurate evaluation of invasion. We experienced 3 surgical cases of tumor of diaphragm:primary mucinous adenocarcinoma, metastatic gastrointestinal stromal tumor, and mesothelioma. Besides computed tomography (CT) and conventional magnetic resonance imaging(MRI), respiratory dynamic cine magnetic resonance imaging (cine MRI) was performed. Cine MRI was acquired using steady state free precession (SSFP) sequence, and about 80 consecutive images of the same slice were taken while a patient breathed deeply. In all cases, cine MRI showed lack of tumor movement along the diaphragm during respiration. During surgery, we found that tumor was originated from diaphragm and there was no adhesion to other organs. Securing a sufficient margin, we resected tumor including the diaphragm. Since the defect of diaphragm was from 4 to 5cm in short diameter, we could close the diaphragm by direct suture. Cine MRI could provide useful information concerning discrimination between diaphragmatic and para-diaphragmatic tumor.

Tracheal Stenosis Associated With Operation for Pneumothorax With Marfan Syndrome: A Case Report.

Marfan syndrome is a genetic disorder in which impaired protein leads to connective tissue weakness. We herein report a case of unexpected tracheal stenosis that was diagnosed just before an operation for a recurrent right pneumothorax with Marfan syndrome. A 16-year-old boy with bilateral repeated pneumothoraces associated with Marfan syndrome came to our emergency room complaining of dyspnea. A chest radiograph showed recurrent right pneumothorax. An operation was planned due to prolonged air leakage even after chest tube drainage. On induction of general anesthesia for repairing pneumothorax, a sudden difficulty occurred during manual ventilation, and the blood oxygen saturation temporarily decreased to 50%. Therefore, emergent intubation with a single-lumen tube was applied, which led back to full saturation. Bronchoscopy revealed a tortuous and flattened trachea. An endobronchial blocker tube was applied due to difficulty in double-lumen tube insertion, and bullectomy was accomplished without any other unexpected events. Patients with Marfan syndrome may have asymptomatic tracheal stenosis due to structural abnormalities and latent tracheomalacia, and general anesthesia could be a trigger to develop the symptoms. Surgeons should bear this in mind, cooperate with anesthesiologists well, and prepare for emergent intubation when managing patients with Marfan syndrome in the perioperative settings.

Pulmonary pleomorphic carcinoma arising in mixed squamous and glandular papilloma: A case report.

Solitary pulmonary papillomas (SPPs) are rare lung neoplasms. Histologically, SPP is classified into three subtypes, and mixed squamous and glandular papilloma (MP) is the rarest subtype. Although SPPs are considered benign tumors, there have been several reports on the synchronous malignant transformation in SPPs. An 82-year-old asymptomatic man was referred to our hospital for further examination of a 2.2 cm-sized left lung tumor. Pathology of bronchoscopic specimens showed the possibility of pulmonary papilloma but did not reveal any malignancy. The patient complained of bloody sputum during the eighth month after the initial visit. The size of the lesion had increased to 4.3 cm. These data suggested the existence of malignancy, and the patient underwent an operation. Histologically, the tumor was composed of fibrovascular cores and papillomatous fronds lined by pseudostratified columnar cells and mucin-filled goblet cells. Keratinizing squamous epithelium was also observed. Overall, the diagnosis of MP was obtained by fundamental histology. In addition, a solid part beneath mild atypical squamous epithelia, which was composed of malignant-appearing squamous cells and spindle-shaped atypical cells, was observed. The spindle portion was positive for cytokeratin AE1/AE3 and vimentin, and focally positive for alpha-smooth muscle actin (αSMA). The final diagnosis was pulmonary pleomorphic carcinoma (PPC) arising in the MP. Only two cases have been reported for atypical spindle tumor cells that are found in MP or bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT), which has histologically similar features to MP. This is the second case report of PPC arising in MP.

Prognostic significance of LAT1 expression in pleural mesothelioma.

Background: The L-type amino acid transporter (LAT1) exhibits significantly increased expression within tumor cells across various neoplasms. However, the clinical significance of LAT1 expression in patients with pleural mesothelioma (PM) remains unclear. Methods: Eighty patients diagnosed with PM between June 2007 and August 2022, were eligible for this study. LAT1, alanine-serine-cysteine transporter 2 (ASCT2), Ki-67, and VEGFR2 were evaluated by immunohistochemistry. Inflammatory and nutritional indices were also correlated with different variables, including neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), systemic immune-inflammation index (SII), prognostic nutritional index (PNI), advanced lung cancer inflammation index (ALI), and Glasgow prognostic score (GPS). Results: LAT1 was highly expressed in 57.5 % of patients with PM. Among the 80 patients included in this study, 65 (81.3 %) received chemotherapy, either alone or followed by surgical resection, while 15 (18.7 %) opted for best supportive care. The level of LAT1 significantly correlated with cell proliferation and ASCT2. Factors such as performance status, histology, LAT1 expression, PNI, ALI, and GPS were significant prognostic indicators for progression-free survival (PFS), while Ki-67, LAT1, NLR, SII, PNI, ALI, and GPS were identified as significant predictors for overall survival (OS). LAT1 expression emerged as an independent prognostic factor for predicting PFS and OS in all patients, as well as in the subgroup of 65 patients receiving chemotherapy. Notably, high LAT1 expression proved to be a significant predictor of outcome, particularly in the subgroup with high PLR and SII. Conclusion: LAT1 was a significant predictor of outcomes in patients with PM and was more predictive of worse outcomes in patients with high inflammatory and low nutritional status.

Prognostic significance of lymph node dissection for lung cancer surgery: a narrative review.

Background and Objective: Theoretically, systematic lymph node dissection (SLND) in lung cancer surgery is a technique that leaves less cancer cells behind and is speculated to improve the prognosis, but its prognostic significance still remains controversial. In addition, the social environment surrounding lymph node dissection has changed with the advent of limited surgery for peripheral small-sized lung cancer and emergence of immune check inhibitor (ICI). Therefore, we reconsidered the role of lymph node dissection. Methods: By referring to past reports, we reviewed the process leading up to the establishment of SLND in lung cancer surgery. We compared five randomized prospective comparative studies on SLND and lymph node sampling (LNS) in lung cancer surgery. Key Content and Findings: Of the five randomized prospective comparative studies, two reported an improvement in overall survival (OS) with SLND, but the remaining three reported no significant difference in OS between SLND and LNS. One out of the five reports revealed a significant increase in complications with SLND. For peripheral non-small cell lung cancer (NSCLC) cases with tumor diameter ≤2 cm and consolidation-to-tumor ratio >0.5 segmentectomy was found to significantly improve the hazard ratio of OS, when compared to a lobectomy. However, the proportion of SLND and lobe-specific lymph node dissection (L-SLND) in each group seems to be unclear. In segmentectomy, the dissection of intersegmental lymph nodes tends to be lenient, and therefore it seems necessary to examine the significance of lymph node dissection in segmentectomy. ICIs are already showing excellent effects, and it may be necessary to examine how they will be affected by removal of regional lymph nodes where cancer-specific cytotoxic T lymphocytes (CTLs) are concentrated. SLND is essential for accurate staging, but ideally-in a host with no cancer cells in the lymph node or a host with cancer cells having a high sensitivity to ICI-it might be better to leave the regional lymph node. Conclusions: SLND may not be the right choice in all cases. A time may come when the extent of lymph node dissection is determined individually for each case. Future verification results are awaited.

A Th1-like CD4+ T-cell Cluster That Predicts Disease-free Survival in Early-stage Lung Cancer.

Perioperative immune checkpoint inhibitors have been shown to improve prognosis in early-stage lung cancer. However, no biomarkers are known to indicate the requirement for treatment. This study aimed to identify T-cell clusters responsible for antitumor immunity in patients with early-stage lung cancer. Preoperative blood samples from 50 consecutive patients with lung cancer who were diagnosed as operable and underwent complete resection were analyzed by mass cytometry. Patients were divided into two groups: no recurrence at a minimum observation period of 851 days (median observation period: 1,031.5 days) and recurrence by the last observation date. Mass cytometry and single-cell RNA sequencing analysis of lymph nodes (LN) and tumor-infiltrating T cells were also performed. CCR4-CCR6+ Th7R showed discriminative ability between recurrence and non-recurrence patients with lung cancer. Patients with more than 3.04% Th7R showed significantly favorable disease-free survival. Th7R was a major component of CD4+ T cells in tumor microenvironments and LNs adjacent to lung cancer tissues and was the only cluster that decreased in peripheral blood after the removal of cancer tissues, suggesting that Th7R was primed and proliferated in tumor-draining LNs in the presence of cancer tissues. Th7R had the kinetics that antitumor T cells should have, as indicated by the cancer immunity cycle; thus, peripheral blood Th7R could represent the potency of tumor immunity by reflecting priming and proliferation in tumor-draining LNs and Th7R in the tumor microenvironment. Prediction using peripheral Th7R before surgery could allow the selection of patients who require perioperative drug therapy and optimize therapeutic interventions with clinical implications. Significance: Peripheral Th7R, a Th1-like CD4+ T-cell cluster reflecting priming status in draining LNs and immune status in the tumor microenvironment, predicts disease-free survival after complete resection and has significant clinical relevance in selecting appropriate therapeutic interventions in patients with early-stage lung cancer.

[Clinicopathologic analysis of small-sized non-small cell lung cancer].

We reviewed the data on 149 patients who underwent complete resection for small-sized (≤ 2 cm)peripheral non-small cell lung cancer at our institution between January 2002 and July 2010. Patients with small-sized lung cancer underwent a lobectomy in 121, segmentectomy in 13, and wedge resection in 15 cases. The overall and 5-year disease-free survivals were 89% and 82%, respectively. The 5-year disease-free survival of patients with tumors exceeding 1.5 cm was lower than that of patients with tumors 1.5 cm or smaller (p=0.01). The 5-year disease-free survival for patients without pleulal invasion was 87%, whereas it was 45% for those with pleulal invasion (p=0.004). The 5-year disease-free survival according to the serum level of carcinoembrionic antigen( CEA) were 82% for the normal group and 70% for the high group( p=0.007). Although the results were not significantly different, patients with tumors with high maximum standardized uptake value (SUV) on FDG-PET/CT showed a trend toward a lower 5-year disease-free survival rate( p=0.10). There were no recurrences in patients with ground-glass opacity (GGO) or GGO-dominant lesion including those who underwent sublober resection. Multivariate analysis showed that tumor size and pleural invasion were independent prognostic factors. Indication of sublober resection for solid-type small-sized non-small cell lung cancer (NSCLC) should be carefully determined considering tumor size, pleural involvement, serum carcinoembryonic antigen( CEA) level, and maximum SUV.

Paravertebral extramedullary hematopoiesis in a case of myelodysplastic syndrome with ring sideroblasts and an SF3B1 mutation.

We present the case of a 56-year-old male patient with paravertebral extramedullary hematopoiesis (EMH) secondary to myelodysplastic syndrome with ring sideroblasts and multilineage dysplasia. In a routine health checkup over 5 years prior, he presented with asymptomatic mild anemia and a posterior mediastinal mass. Pathological and cytomorphological findings of the resected paravertebral mass were similar to those of his bone marrow specimen, and included cellularity with erythroid hyperplasia, multilineage dysplastic changes, and the presence of ring sideroblasts. A concordant SF3B1 mutation was detected in both bone marrow and paravertebral mass samples, suggesting that the EMH cells were derived from the bone marrow.

Chylothorax associated with lymphatic reflux in a thoracic duct tributary after lung cancer surgery.

Chyle leaks are attributed to damage to the thoracic duct itself or its tributaries during surgery. Chylothorax after lung cancer surgery can occur due to damaged thoracic duct tributaries; however, little is known of the mechanism involved. A 71-year-old female underwent a left upper lobectomy with hilar and mediastinal lymphadenectomy for a 1.8-cm primary squamous cell carcinoma, and developed a chylothorax a day later. Catheter lymphangiography revealed high-flow chyle leaks from a damaged thoracic duct tributary, known as a bronchomediastinal lymph trunk, due to a lymphatic reflex from the thoracic duct. Subsequently, catheter embolization of the tributary repaired the chylothorax. The potential for persistent chylothorax after lung cancer surgery and successful lymphatic intervention should be noted.

Tumor immunity is related to 18 F-FDG uptake in thymic epithelial tumor.

BACKGROUND: 2-deoxy-2-[fluorine-18] fluoro-d-glucose (18 F-FDG) positron emission tomography (18 F-FDG-PET) is a convenient modality to assess the metabolic activity within tumor cells. However, there is no consensus regarding the relationship between 18 F-FDG uptake and the immune environment in thymic epithelial tumors (TETs). We conducted a clinicopathological study to elucidate the relationship between 18 F-FDG uptake and programmed death ligands 1 and 2 (PD-L1/PD-L2) expression in patients with TETs. METHODS: A total of 108 patients with histologically confirmed TETs classified as thymomas or thymic carcinomas who underwent surgical resection or biopsy or needle biopsy and 18 F-FDG PET before any treatment between August 2007 and March 2020 were enrolled in this study. Tumor specimens underwent immunohistochemical staining for PD-L1, PD-L2, GLUT1, HIF-1α, VEGFR2, VEGF-C, and ß2 adrenergic receptor. RESULTS: High uptakes of SUVmax , SUVmean , MTV, and TLG were identified in 28 (25.9%), 61 (56.5%), 55 (50.9%), and 55 (50.9%) of 108 patients, respectively. High uptake of SUVmax significantly correlated with PS (performance status) of 1-2, thymic carcinoma, and advanced stage, and SUVmax on 18 F-FDG uptake displayed a close association with PD-L1 and PD-L2 expressions, but not with MTV and TLG. Our analysis revealed that SUVmax was identified as being significant relationship for positive PD-L1/PD-L2 expression. GLUT1, HIF-1α, and VEGFR2 were significantly associated with the expression of PD-L1/PD-L2 from the biological viewpoint. CONCLUSION: 18 F-FDG accumulation was closely associated with the expression of PD-L1/PD-L2, which, in turn, was correlated with glucose metabolism and hypoxia. PD-L1/PD-L2 could affect the glucose metabolism and hypoxia in thymic tumor cells.

[Pancoast tumor receiving preoperative concurrent chemoradiotherapy followed by radical resection via transmanubrial approach and posterior thoracotomy].

A 59-year old man complaining of right shoulder pain was diagnosed with Pancoast tumor. Chest computed tomography (CT) scan showed a right superior sulcus tumor, 5.8 cm in diameter, invading the middle-posterior compartment of thoracic inlet. Chest magnetic resonance imaging (MRI) sagittal section showed the possibility of infiltration to subclavian artery. The patient received preoperative concurrent chemoradiotyrapy (CCRT) [radiotherapy : 60 Gy/30 Fr, cisplatin and docetaxel], resulting in tumor regression (PR). The patient underwent right upper lobectomy and resection of the 1st- 2nd ribs and Th1 nerve via transmanubrial approach and high posterior thoracotomy. Pathological examination demonstrated a little live cancer cells and organization of necrotic tissue in the lung and inter costal region (Ef2). Transmanubrial osteomuscular sparing technique maintains an excellent exposure of thoracic inlet and cervical structures safely.

Pulmonary high-grade fetal adenocarcinoma associated with cystic airspace: A case report.

Lung cancers associated with cystic airspaces have a life-threatening risk of a missed or delayed diagnosis. Here, we report a case of pulmonary high-grade fetal adenocarcinoma, a rare lung carcinoma associated with cystic airspaces, as confirmed by computed tomography (CT) scan. A 73-year-old asymptomatic male with a 52-pack a year smoking habit was referred to our hospital. Lung CT showed a thin-walled cystic space with exophytic and endophytic solid nodules along the cyst wall. After surgery, histological analysis of a resected lung specimen revealed a pure high-grade fetal adenocarcinoma probably associated with emphysematous bullae in pulmonary emphysema, suggesting smoking contributed to this pure form, as well as the emphysema. In conclusion, when treating elderly men with a smoking history, physicians need to carefully examine the walls of cystic airspaces on CT for fetal adenocarcinoma. KEY POINTS: Significant findings of the study •Pulmonary high-grade fetal adenocarcinoma may be associated with emphysematous bullae manifesting as cystic air spaces as shown by computed tomography. What this study adds •When scanning by computed tomography, physicians should carefully examine the pulmonary cystic airspace walls in elderly men with a smoking history.

[Intrapleural perfusion hyperthermo-chemotherapy with cisplatin in patients with malignant pleural mesothelioma].

The preferred treatment for patients with malignant pleural mesothelioma (MPM) has not been determined. In order to obtain adequate control of malignant effusion for multimodality therapy, we have introduced intrapleural perfusion hyperthermo-chemotherapy (IPHC) with cisplatin. IPHC was performed with a roller pump and heat exchanger. Cisplatin was added when the temperature stabilized to a mean of 42.5 degrees C. Dosages of cisplatin were 80 mg/m2. The circuit was filled with 2,000 ml saline. A IPHC was performed for 60 minutes under both lung ventilation. IPHC with cisplatin is feasible, easy to perform, and relatively safe. This method had brought an ideal pleural adhesion. IPHC may offer excellent local control for patients with MPM. Some literatures have reported the utility of IPHC for trimodality therapy on MPM.

Pulmonary intravascular large B-cell lymphoma accompanying synchronous primary pulmonary adenocarcinoma and benign interstitial lesions.

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of extranodal large B-cell lymphoma, and initial or predominant presentation in the lungs is uncommon. The synchronous occurrence of IVLBCL and malignant tumors is less frequent, and no such reports have described pulmonary presentations. We report a rare case of pulmonary IVLBCL accompanying lung cancer and interstitial lesions. A 73-year-old man with a history of pneumonia underwent a follow-up examination. Computed tomography revealed diffuse, bilateral ground-glass opacities (GGO) with a partial solid mass. Histologically, the mass consisted of adenocarcinoma. However, two other types of interstitial lesions were scattered throughout the resected lung: 1) peribronchovascular thickening with the aggregation of macrophages and anthracosis, and 2) alveolar septal thickening in the centrilobular area with atypical CD20-positive large cells in the capillaries. These two types of lesions were not mixed. Computed tomography and positron emission tomography demonstrated no other organ involvement. The patient was considered to have the synchronous occurrence of pulmonary IVLBCL and lung cancer (adenocarcinoma). After R-CHOP therapy, GGO on CT disappeared. Lung cancer often accompanies benign background lesions, and the combination of these lesions with lung cancer may make it difficult to detect the presence of pulmonary IVLBCL. However, the histological distribution pattern of IVLBCL may be a clue to the correct diagnosis.

Primary pulmonary synovial sarcoma with calcification: A case report.

The lung is the organ most commonly affected by primary synovial sarcoma. Intratumoral calcification is less common in this organ versus soft tissue. Meanwhile, the presence of calcification in a lung nodule reduces the risk of lung cancer. Here, we report a case of pulmonary synovial sarcoma which manifested as a nodule with calcification, depicted on computed tomography (CT). A 52-year-old asymptomatic male was referred to Saitama Medical University International Medical Center and CT revealed a well-defined nodule (1.8 cm), with punctate and eccentric calcification in the right lower lobe. Enhanced CT and 18F-fluorodeoxyglucose positron-emission tomography suggested a malignant tumor, and surgery was performed. Histology provided a preliminary diagnosis of monophasic spindle-cell synovial sarcoma with hyalinized collagen bands and calcifications. Genetically, the presence of the SYT-SSX2 fusion gene was consistent with the features of this disease. We conclude that primary pulmonary synovial sarcoma should be listed as a differential diagnosis for solitary pulmonary nodules with calcification.

Optimal sublobar resection for c-stage I non-small cell lung cancer: significance of margin distance to tumor size ratio and margin cytology (Supplementary analysis of KLSG-0801): complete republication.

BACKGROUND: Sublobar resection for lung cancer is associated with a higher risk of recurrence than that of lobectomy; we evaluated the factors considered to be predictors of recurrence. METHODS: By analyzing multicenter prospective studies of sublobar resection for patients with c-stage I non-small lung cancer who were unable to undergo lobectomy (KLSG-0801), we investigated the relationship between (1) tumor location (TL) and margin distance from the stump (MD), (2) the MD/tumor size (TS) ratio and prognosis, (3) and the margin cytology (MC) and prognosis. RESULTS: The correlation between TS and MD was statistically significant in cases of easily resectable regions defined by Lewis' classification (n = 18). However, there was no correlation in difficult-to-resect regions (n = 14). Among cases of recurrence, the MD/TS ratio was less than 1. The 3-year survival rate was 100% for patients with MD/TS > 1 (n = 12), 59.7% for patients with MD/TS ≤ 1 (n = 20) (p = 0.06), 88.1% in cases of negative MC (n = 18), and 20% in cases of positive MC (n = 5) (p = 0.001). CONCLUSION: Cases with positive MC had a significantly worse prognosis than those with negative MC. It may be difficult to secure an MD greater than the TS in a difficult-to-resect region according to Lewis' classification.

Distinctive clinicopathological features of adenocarcinoma in situ and minimally invasive adenocarcinoma of the lung: A retrospective study.

OBJECTIVES: The aim of this study was to investigate distinguishing clinicopathological features, in addition to histological invasiveness, in adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) of the lung. MATERIALS AND METHODS: Patients with lung adenocarcinoma who underwent surgery at our hospital between 2007 and 2014 were reviewed, focusing on computed tomography (CT) images, operative procedures and clinical outcomes, histopathology, Ki-67 immunostaining, and EGFR-mutation status. EGFR mutations were examined using a peptide nucleic acid-locked nucleic acid PCR clamp method. Group comparisons were investigated by Mann-Whitney U or Fisher's exact tests. RESULTS: Of 629 patients with lung adenocarcinoma who underwent surgery, 91 (14%) of 103 AIS (n = 34) or MIA (n = 69) tumors were reviewed. The ratio of male to female patients with MIA compared to AIS was significantly higher (p < 0.02). Of 103 tumors, 99 (96%) were non-mucinous. By CT, 74% of AIS appeared as pure ground-glass nodules and 75% of MIAs as part-solid ground-glass nodules. Pathological tumor diameters and Ki-67 labeling index (LI) values were significantly greater for MIAs compared to AIS (p < 0.001 for both). A Ki-67 LI of ≥2.8% indicated the presence of an MIA rather than an AIS. EGFR mutations were more frequently detected in MIAs (33/69, 48%) than AIS (9/34, 26%; p = 0.055). The ratio of exon 19 deletions to exon 21 missense mutations in MIAs tended to be higher than those in AIS (p = 0.06). Patients did not experience a local recurrence or metastasis after AIS and MIAs were removed by wedge resection, segmentectomy or lobectomy. Five-year recurrence-free survival rates were 100%. CONCLUSION: Despite similar surgical outcomes for AIS and MIAs, we found differences in terms of gender, tumor diameters, CT findings, Ki-67 LI and a subset of EGFR mutations, highlighting the validity of classifying the two subtypes.