These subtypes are described below:

lepidic predominant 
acinar predominant 
papillary predominant 
micropapillary predominant 
solid predominant with mucin production Cell patterns identifying subtypes are associated with prognosis, ranging from favorable (lepidic) to intermediate (acinar and papillary) to poor (micropapillary and solid).Four discrete variants of invasive adenocarcinomas not assignable to these five subtypes are also included in the current classification:

invasive mucinous adenocarcinoma 
colloid adenocarcinoma 
fetal adenocarcinoma 
primary pulmonary enteric adenocarcinoma

Imaging
A chest x-ray (radiograph) is often the first imaging test performed when a person presents with cough or chest pain, particularly in the primary care setting. A chest radiograph may detect a lung nodule/mass that is suggestive of cancer, although sensitivity and specificity are limited.CT imaging provides better evaluation of the lungs, with higher sensitivity and specificity for lung cancer compared to chest radiograph (although still significant false positive rate). Computed tomography (CT) that is specifically aimed at evaluating lung cancer includes the chest and the upper abdomen. This allows for evaluation of other relevant anatomic structures such as nearby lymph nodes, adrenal glands, liver, and bones which may show evidence of metastatic spread of disease. Indeed, the US Preventative Services Task Force recommends annual screening with low-dose CT in adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years, with certain caveats (see Lung cancer screening).Nuclear medicine imaging, such as PET/CT and bone scan, may also be helpful to diagnose and detect metastatic disease elsewhere in the body.
Episodes of recurrent pneumonia in the same lung field should prompt evaluation for a possible foreign body in the airway.Whether or not the foreign body is removed, complications such as chemical bronchitis, mucosal reactions, and the development of granulation tissue are possible.Complications can also arise from interventions used to remove a foreign body from the airway. Rigid bronchoscopy is the gold standard for removal of a foreign body, however this intervention does have potential risks. The most common complication from rigid bronchoscopy is damage to the patients teeth. Other less common complications include cuts to the mouth or esophagus, perforation of the bronchial tree, damage to the vocal cords, pneumothorax, atelectasis, stricture, and perforation. Prevention

There are many factors to consider when determining how to decrease the likelihood of aspiration, especially in the extremely young and elderly populations.The major considerations in children are their developmental level in terms of swallowing and protecting their airway via mechanisms such as coughing and the gag reflex. Also, certain object characteristics such as size, shape, and material can increase their potential to cause choking among children. When there are multiple children in a shared environment, toys and foods that are acceptable for older children often pose a choking risk to the younger children. Education for parents and caretakers should continue to be prioritized when possible. This can be through positions such as pediatricians, dentists, and school teachers as well as media advertisements and printed materials.