Pulmonary mucinous adenocarcinomas: a clinicopathologic series with emphasis on the prognostic significance of spread through alveolar spaces, and presence of solid growth component

Mucinous Adenocarcinoma of the Lung: A Great Mimicker of Pneumonia

Mucinous adenocarcinoma is a rare lung cancer that can mimic the appearance of infectious pneumonia on imaging. The present report describes the case of an 88-year-old man who presented with a cough that was not responsive to treatment. Based on chest X-ray findings consistent with pneumonia, he was treated with oral antibiotics. After the patient's symptoms did not improve, a computed tomography scan was performed, which showed a confluent consolidation in the left lower lung and a cavitation suggestive of pneumonia. The patient was then admitted to the hospital to receive intravenous antibiotics. Although his cough continued, laboratory findings were within normal ranges and bacterial cultures were negative. He underwent two bronchoscopy procedures with bronchoalveolar lavage and was diagnosed with parainfluenza and rhinovirus/enterovirus, for which he was treated with prolonged antibiotics and steroids. His symptoms still failed to improve, and a bronchoscopy with cryobiopsy was performed, with a positive result for mucinous adenocarcinoma. This case illustrates the need to distinguish mucinous adenocarcinoma from pneumonia to improve the early diagnosis of this rare cancer and patient outcomes.

The prognostic value of histopathology in invasive lung adenocarcinoma: a comparative review of the main proposed grading systems

INTRODUCTION

An accurate histological evaluation of invasive lung adenocarcinoma is essential for a correct clinical and pathological definition of the tumour. Different grading systems have been proposed to predict the prognosis of invasive lung adenocarcinoma.

AREAS COVERED

Invasive non mucinous lung adenocarcinoma is often morphologically heterogeneous, consisting of complex combinations of architectural patterns with different proportions. Several grading systems for non-mucinous lung adenocarcinoma have been proposed, being the main based on architectural differentiation and the predominant growth pattern. Herein we perform a thorough review of the literature using PubMed, Scopus and Web of Science and we highlight the peculiarities and the differences between the main grading systems and compare the data about their prognostic value. In addition, we carried out an evaluation of the proposed grading systems for less common histological variants of lung adenocarcinoma, such as fetal adenocarcinoma and invasive mucinous adenocarcinoma.

EXPERT OPINION

The current IASLC grading system, based on the combined score of predominant growth pattern plus high-grade histological pattern, shows the stronger prognostic significance than the previous grading systems in invasive non mucinous lung adenocarcinoma.

Quantitative CT imaging analysis to predict pathology features in patients with a congenital pulmonary airway malformation

BACKGROUND

Risk for infection and potential malignant degeneration are the most common arguments for resecting asymptomatic Congenital Pulmonary Airway Malformations (CPAM). We aimed to investigate if CT- imaging characteristics can be used to predict histopathological features, by using an objective quantitative CT scoring method.

METHODS

Archival CPAM tissue samples were histologically re-assessed and patients who had a pre-operative volumetric CT-scan were included. Lung disease was quantified using the newly-developed congenital lung abnormality quantification(CLAQ) scoring method and obtained percentages were used to predict histopathological signs of inflammation and presence of mucinous proliferation (MP). Because MP is presumed a precursor for mucinous adenocarcinoma in situ (AIS) this method was also used to compare CT-scans of patients with AIS to those with only CPAM.

RESULTS

Thirty-three CPAM patients were included of which 13(39%) had histological signs of inflammation and 8(24%) had a MP. Patients with inflammation had a significantly smaller lesion (14% vs 38%) while those with MP had more extensive disease (54%vs17%). Patients with AIS had a significantly smaller lesion compared to CPAM patients (5%vs29%). Significant predictors for inflammation were smaller lesion size and percentage hypodensity within lesions while a larger lesion size and percentage parenchymal hyperdensity (solid lung tissue components) were predictors for MP as well as AIS.

CONCLUSIONS

Smaller CPAM lesions may be more susceptible to inflammation while larger lesions may be associated with the presence of MP. Parenchymal hyperdensity is found as a predictor for MP as well as AIS and should therefore elicit more extensive gross sampling.

LEVEL OF EVIDENCE

Level III.

Clinicopathological features of pulmonary mucinous adenocarcinoma: A descriptive analysis

BACKGROUND

Mucinous adenocarcinoma is a rare subtype of lung cancer characterized by abnormal mucin production. We sought to investigate the clinical and pathological features of pulmonary mucinous adenocarcinomas and to identify prognostic factors.

METHODS

This was a single-institution retrospective review of patients with pulmonary mucinous adenocarcinoma diagnosed between January 1, 2015 and December 31, 2020. Descriptive analysis included demographics, diagnostic data, and treatment modalities. The primary outcome was overall survival (OS).

RESULTS

Fifty-six patients were included in the study. Median age was 65 years (range: 26-84), 30 (54%) were female, 48 (86%) had a smoking history, and 41 (73%) patients had ECOG performance status 0-1. Nearly half (26, 46%) were stage IV at presentation, while 11 (20%) presented as stage I, 10 (18%) stage II, and 9 (16%) stage III. Biomarker testing increased through the study period. Where performed, 4/48 (8%) cases were ALK positive, but there were no EGFR cases identified (0/36). Only 3/20 cases had PD-L1 expression >50%. Curative intent therapy was performed in 23 patients (17 had surgery +/- chemotherapy/radiation, 4 had radiotherapy alone, 2 had chemoradiation). Median OS in the entire population was 16.1 months (m). OS by stage was 50.0m for stage I, not reached for stage II, 20.7m for stage III, and 8.1m for stage IV.

CONCLUSIONS

The overall prognosis of pulmonary mucinous adenocarcinoma appears similar to that of non-mucinous adenocarcinomas, with distinct differences noted in the incidence of oncogenic driver mutations, particularly an absence of EGFR mutations.

Primary mucinous carcinomas of the lung: Clinical characteristics and treatment outcomes

Introduction

Invasive mucinous adenocarcinoma (IMA) of the lung is a distinct histologic variant of adenocarcinomas comprising about 2%-10% of lung adenocarcinomas. A large proportion of IMAs carry KRAS mutations and only rarely epidermal growth factor receptor (EGFR) mutations or ALK/ROS translocations; thus, most cases are not amenable for targeted therapy at present. This study was conducted to elicit the unique clinicopathological characteristics of IMA.

Materials and Methods

Medical records of patients diagnosed with IMA by needle biopsy at Kidwai Cancer Institute, Bangalore, from 2013 to 2018, were retrieved and reviewed. Statistical analysis was performed using SPSS version 23.0 (IBM Corp., Armonk, NY, USA).

Results

Four hundred and ninety cases of needle biopsy of the lung were diagonosed at our institute between January 2013 and December 2018. Nine cases (1.8%) were diagnosed as IMA. The median age of presentation was 59 years. Six (66.7%) were current smokers with pack-year > 20. Three (33.3%) of the cases were initially misdiagnosed as pneumonia in view of computed tomography findings. The lung was the most common site of metastasis (77.8%). Serum Carcinoembryonic Antigen (CEA) was elevated in six cases (66.7%). None of the cases had any driver mutations in EGFR gene or ALK and ROS1 translocations. All cases were treated with pemetrexed-carboplatin doublet followed by pemetrexed maintenance till progression. The median progression-free survival (PFS) was 15 months (range: 5-18 months). Docetaxel was given as the second-line chemotherapy in all progressed patients. Best response noted was stable disease, seen in 4 (57.1%) cases. The median PFS for docetaxel was 6 months (range: 3-8 months). The median overall survival was 22 months (range: 9-27 months). Patients with initially raised CEA at progression had a serial rise in serum CEA.

Conclusions

IMA is rarely diagnosed on needle biopsies due to insufficient tissue. They mimic pneumonia on imaging, thus delaying diagnosis. EGFR mutations, ALK, and ROS1 translocations are usually negative making them ineligible for tyrosine kinase inhibitors. Response to chemotherapy is modest.