Recurrent Pneumonia due to chronic retention of foreign body, which mimics a bronchial tumor is a rare observed condition in adults (1). Bronchoscopy is an uncommon indication for foreign body aspiration in adults, accounting for 1% of procedures (2). The diagnosis of the foreign body aspiration is often delayed or overlooked, leading to patients experiencing chronic cough, recurrent pulmonary infections and persisting dyspnea (3, 4). Cryotherapy with flexible cryoprobe is a safe technique for treatment of symptomatic endobronchial tumor stenosis, cryoextraction and quick removal of foreign bodies (5–8). Furthermore, actinomycosis associated with foreign body aspiration is a rare pulmonary infection, caused by inhalation of actinomyces contaminated aspiration (9).

Here, we report two unique cases of cherry pit aspiration, who unconsciously aspirated a cherry pit months or years prior to recurrent pulmonary infections. The patients were not aware of any aspiration. Bronchoscopy is the recommended initial management and diagnostic procedure for patients experiencing recurrent pulmonary infections, unresolved actinomycosis resistant to antibiotics regardless whether or not they have a history of aspiration.

Foreign body aspiration (FBA) is an uncommon event in the adult population. In these case series study, the patient in case 1 presented with symptoms of pneumonia, and his chest CT scan revealed a consolidation in the right upper lobe, and in case 2 presented with persistent actinomycosis infection resistant to antibiotics and dyspnea in exertion, in both cases resembling an endobronchial tumor. Since the recurrent pneumonia and persistent actinomycosis were the main reasons for admission to the hospital, we performed a bronchoscopy for further diagnostical purpose. However, in case 1 the patient can remember eating cherries 6–8 months before admission to hospital, but did not notice any aspiration of it, whereas in case 2 the patient did not notice any aspiration, after a long latency of the cherry pit. We suppose that the aspiration symptoms were mild due to their elderly and poor general condition. In case 1 during bronchoscopy showed a complete occlusion of the right upper lobar bronchus and hyperplasia tissue covered with purulent secretion resembling an endobronchial tumor. The obstruction including epithelium hyperplasia was carefully removed with a cryoprobe (Figure 2D; Supplementary Video S1). In case 2, in bronchoscopic examination revealed a partial occlusion of the left lower lobe with a tumor mass, hyperplasia tissue covered with purulent secretion mimicking also a lung tumor (Figures 3A–F), which was carefully removed with a cryoprobe (Figure 3F). Foreign body aspiration usually occurs in children, and the other peak at over 60 years of age accounting for 20% aspiration cases (10, 11). A foreign body aspiration can be tolerated in the elderly ages leading to recurrent pneumonia, and patients presenting with symptoms due to infection and other complications such as pneumothorax, or endobronchial tumor (12). Colleagues Li et al. prescribed a case report of watermelon seed aspiration in a cancer patient resembling a recurrence (3). Furthermore, actinomycosis is a purulent infection caused by filamentous bacilli, and pulmonary actinomycosis presented only 15% of actinomyces infection (13). Pulmonary actinomycosis is presented in various form, including pneumonia, a pseudo-tumor-like mass, draining fistulas, pulmonary abscess or tuberculosis (14, 15). Actinomycosis clinical cases due to nonorganic FBA have been reported in the literature such as secondary to pen end cap, or watermelon seed aspiration (16, 17).

However, there are no reports of cherry pit aspiration and adenomatous hyperplasia with lymphoplasmacellular bronchitis, squamous epithelium metaplasia, actinomycosis infection mimicking also macroscopically a lung cancer.

Foreign body aspirations are often characterized with histopathologic sequela of chronic inflammatory changes, including lymphocyte and plasma cell infiltration, fibrosis, and the formation of foreign body giant cells and granulomas (18). The changes resembling a tumor mass were seen in our clinical case, adenomatous hyperplasia adjacent to the aspirated cherry pit, which also revealed in addition squamous metaplasia. Secondary bacterial colonization by coccoid and filamentous bacteria were observed in H&E staining (Figure 2F). Interestingly in pathological specimen was observed clearly typical water-clear plant cells, with typical birefringence as evidence of foreign plant material (Figures 2E–H). Furthermore, a macroscopic view of a cherry pit foreign body could be finally observed in a specimen container (Figures 2D, 3F). Squamous epithelium metaplasia is normally seen as secondary to the toxic injury of the airways as precursor of squamous cell carcinoma (19). Squamous metaplasia has been documented to happen in smokers with chronic obstructive pulmonary disease, due to chronic toxic injury, expressing carcinoembryonic antigen (19). Additionally, epithelium squamous metaplasia possibly caused by aspiration of a pistachio shell, was detected during a CT-Screening for lung cancer, and supported in PET-CT scan for lung tumor (20). Similar cases of chronic inflammation and induction of squamous metaplasia due to retention of oral chaff debris in rat feed were observed in animal models (21). This phenomenon is also presented in our cases, in which adenomatous hyperplasia and epithelium squamous metaplasia were observed in addition to the chronic inflammation, purulent secretion and aspirated cherry pit. Both chronic smoking and FBA have been shown to induce epithelium squamous metaplasia, it might be unclear if the cherry pit is only responsible factor, and smoking is additional factor contributed to the event. Juan et al. showed that DNA damage has the potential to drive the squamous metaplasia via mitotic checkpoints, opening novel molecular candidate targets for lung squamous cell carcinoma (22). Furthermore, atypical adenomatous hyperplasia is prescribed as risk factor for lung cancer (23).

Once the FBA is suspected with detailed clinical history and imaging findings, bronchoscopy is the next step in management of foreign body retrieval. Flexible bronchoscopy is a valuable procedure, with less discomfort, performing under light sedation, and enables access to the peripheral airways in medical centers where rigid bronchoscopy is not available (24). However, rigid bronchoscopy has been favored historically for foreign body removal in the pediatric population.

Cryotherapy with flexible cryoprobe is a safe technique for treatment of symptomatic endobronchial tumor stenosis, cryoextraction and quick removal of foreign bodies (5–8).

Cryobiopsy has emerged as a safe and effective method in diagnostics, with additional benefits over conventional biopsy when used in combination with radial endobronchial ultrasound (25, 26). Furthermore, cryoprobe plays a crucial role in the cryorecanalization of malignant airway obstruction, leading to improved patient survival (27). Additionally, use of cryoprobe has been proven safe and feasible for the retrieval of both organic and inorganic foreign body aspirations, providing a versatile tool for medical professionals (7).

The pneumonia in the follow-up CT in both cases were completely resolved (Figures 1E–H, 3C,D). Minor changes with persistent bronchiectasis in follow-up CT, are most likely in resolving process of pneumonia, or in chronic latency in case 2 associated with COPD.

In case 2 the tumor mass associated with pulmonary actinomycosis reported here was most likely due to the aspiration of the cherry pit, which had been present in the lung for a long duration, ca. 2 years. This indicates in addition, the importance of keeping actinomycosis of the lung in the differential diagnosis of pseudo-tumor of a lung lesion, a bronchoscopy after resolution of the local inflammation is imperative, and samples should be also for tissue diagnosis and regular culture. In elderly patients with aspiration risk, prevention of aspiration with upright positioning during meals, supervision from nurses, and routine oral care are crucial factors (28).

In conclusion, bronchoscopy examination should be considered as a diagnostic tool in cases of recurrent pneumonia or persistent actinomycosis that are resistant to antibiotics, to exclude any chronic foreign body retention as a potential underlying cause of the event. In addition, cryoprobe is safe, efficient and feasible method in retrieval of bronchial adenomatous hyperplasia resulting from chronic foreign body retention. This clinical novel rarity, with recurrent pneumonia or endobronchial actinomycosis associated with foreign body aspiration, which mimics a lung tumor with well-defined edges, requires special attention from medical staff in specific situations.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author/s.

The studies involving humans were approved by Justus Liebig University Medizinisches Lehrzentrum. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

GO: Conceptualization, Data curation, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, Methodology, Software, Validation, Visualization. GK: Data curation, Formal analysis, Investigation, Writing – review & editing. SG: Formal analysis, Investigation, Resources, Writing – review & editing. SH: Data curation, Formal analysis, Investigation, Writing – review & editing. IV: Data curation, Formal analysis, Investigation, Writing – review & editing. WS: Conceptualization, Investigation, Supervision, Writing – review & editing. KT: Data curation, Formal analysis, Investigation, Supervision, Validation, Writing – review & editing, Writing – original draft, Conceptualization, Visualization. MH: Data curation, Formal analysis, Investigation, Supervision, Validation, Writing – review & editing, Writing – original draft, Conceptualization, Methodology, Visualization.