As for foreign body aspiration, clear history of inhalation and special clinical manifestations are helpful for confirming the diagnosis. However, few cases in the present study had an exact history of aspiration, and their clinical manifestations were atypical because eating pepper could also cause cough, thus the definite diagnosis was difficult. Although the clinical manifestations are atypical, which tend to gradually worsen in some patients and some cases may have poor results with conventional treatment. Therefore, the possibility of obstructive pneumonia should be considered. The bronchopulmonary abnormalities caused by pepper aspiration were found to have some characteristics on CT images, which mainly manifested as U/V-shaped or annular high density or localized soft tissue density in the lower lobe bronchus, extensive wall thickening with stenosis or occlusion in the surrounding bronchi, and consolidation or atelectasis in the multiple distal lung segments.
Previous studies have reported that foreign body in adult patients was more frequently located in the right bronchus tree, especially the right lower bronchus[11, 14, 15, 19, 20]. In this study, the most common site of pepper impaction was also the right lower lobe bronchus, which is consistent with previous results. The higher frequency of aspiration into the right bronchial tree appears to be due to the vertical nature of right main bronchus, larger diameter, and the greater airflow through it[19, 21]. In addition, most of the cases were found with pepper segments but not pepper fragments. This may be related to the different sizes of pepper, the bigger pepper segments are more difficult to be coughed up than the smaller fragments.
The clinical manifestations of foreign body aspiration can vary, depending on the degree and duration of obstruction, as well as the size and location of the foreign body[12]. The most common symptom is cough, other symptoms include choking, vomiting, cyanosis, wheezing, stridor, dyspnea, chest pain, hemoptysis, sneezing, fever, and sputum[12–15, 22, 23]. In this study, the most common symptoms were cough and sputum, while the others were relatively rare. The reason for this may be due to the active ingredient of pepper, which can also induce respiratory symptoms. Moreover, the pepper was soft and hollow, the taper-like pepper or tiny fragments were seldom lodged in the tracheal or main bronchus, so symptoms like choking and wheezing were rare. In addition, after antibiotic treatment, the patients' chronic respiratory symptoms may recurrent or do not improve significantly. Because of ignorance or neglect, the aspiration event might be covered up by an accompanying cough that was mistakenly attributed to the stimulation of pepper. Therefore, it is difficult to make a diagnosis by symptoms alone, but there is a possibility of obstructive pneumonia.
The positive detection of foreign bodies on CT images largely depends on the physical properties of the aspirated material and the slice thickness[16]. Substances like radiopaque materials are more easily detected, such as metals and bones[8]. Organic food items are the most commonly aspirated foreign bodies[13, 24]. Due to their radiolucent nature, they cannot be directly detected on CT[8, 13]. In this study, in combination with the bronchoscopy findings, it was revealed that a small proportion of pepper showed circular or U/V-shaped high density, which may be related to the occurrence of calcification in it. This manifestation is more specific because the shape of pepper could be described. In contrast, more intraluminal peppers showed as localized soft tissue density or flocculent opacification, which may be a manifestation of pepper mixed with surrounding granulation tissue and contained secretions. This unspecific manifestation needs to be distinguished from early bronchogenic carcinoma. Previous studies have found that the latter had mostly a hilar location, and commonly manifested as endobronchial nodular protrusion without extensive bronchial thickening[25–27]. Additionally, persistent endobronchial focal soft tissue density or flocculent opacification without enhancement should also be considered as a possibility of foreign body obstruction.
In addition to the pepper itself, changes of surrounding structures also need to be noticed. In this study, the bronchi adjacent to pepper were extensively involved and presented as significant bronchial wall thickening with lumen stenosis or occlusion. These changes may be related to the long-lasting stimulation of pepper and recurrent inflammation. Moreover, the obstructive pulmonary lesions were consistent with the bronchial involvement, which manifested as multiple segmental consolidation or atelectasis with or without bronchiectasis. Previous studies also reported that obstructive pneumonia included bronchiectasis and bronchiolectasis with mucous plugging, a variety of parenchymal inflammatory changes, and significant atelectasis[5]. Therefore, when looking for the cause of protracted segmental consolidation or atelectasis with or without bronchiectasis, more attention should be paid to the proximal bronchi and their patency.
Previous studies have reported that other features caused by foreign bodies included hilar lymph node enlargement and pleural effusion, especially the former[11, 14–16, 28], which were most likely secondary to the long-term recurrent infection[29]. In this study, the majority of patients also had regional lymph node enlargement, while few cases had pleural effusion. Bronchiectasis usually occurs secondary to chronic or recurrent infection, which could lead to bronchial artery dilatation[30]. In this study, bronchial artery dilatation was present in most patients who underwent enhanced CT scan, which also indicated the chronic process of pulmonary lesions. Therefore, pulmonary lesions with regional lymph node enlargement and bronchial artery dilatation indicates the higher possibility of chronic inflammation rather than tumors.
This study has several limitations. First, some peppers without normal shape or color are difficult to be identified, which leads to a relatively small sample size in present study. Second, not all peppers could be visualized on CT images directly unless calcification occurred in them because they were frequently surrounded by granulation tissue. Thus, the present findings may be more applicable to the district or people with specific dietary history. Third, the value of enhanced CT images in identifying bronchopulmonary lesions caused by pepper is unclear because enhanced CT scan was not performed in all the patients.