Localized Bronchiectasis Secondary to an Allergic Response Provoked by Vertebral Osteophytes

Abstract

Thoracic vertebral osteophytes have been reported to affect the adjacent organs. We report an uncommon case of localized bronchiectasis secondary to an allergic reaction stimulated by vertebral osteophytes. A man in his 60s presented with a 2.5-cm lung nodule connected to the proximal segmental bronchus in the right lower lobe near vertebral osteophytes that caused obstructive pneumonia due to mucoid impaction. His medical history suggested a tendency for development of allergic respiratory tract reactions. Thoracoscopic resection was successfully performed, and histopathologic examination confirmed the pathogenesis.

Thoracic vertebral osteophytes (TVOs) have been reported to affect adjacent intrathoracic organs, such as the esophagus, descending aorta, right main bronchus, and pulmonary vein.^1,2 The pathogenesis of most of these cases was direct compression. Notably, to the best of our knowledge, there is no report about TVOs causing localized bronchiectasis (LB) in the adjacent pulmonary tissue.

We present a case of resected LB near TVOs in a nonsmoking man in his 60s who was referred for the evaluation of a lung nodule in the right lower lobe. The nodule was detected incidentally on computed tomography (CT) for suspected cholecystitis. He had a history of allergic rhinitis, bronchial asthma, and previous radical chronic sinusitis surgery. In addition, his mother and daughters had allergic rhinitis. He did not have visceral inversion or diffuse bronchiectasis, characteristic of immotile cilia syndrome. A high eosinophil count was recorded consistently on blood tests. The pulmonary function test indicated obstructive ventilatory defect (vital capacity, 88.2% predicted; forced expiratory volume in 1 second, 2500 mL; forced expiratory volume in 1 second/forced vital capacity ratio, 65.2%). CT revealed a 2.5-cm solid nodule with smooth margins in the right posterior basal segment (Figure 1A). The nodule was connected to the proximal segmental bronchus with a thickened wall. Near the nodule, protrusions of osteophytes of the 10th to 12th thoracic vertebrae were observed, whereas CT performed 15 years earlier did not reveal either the nodule or protrusions. Positron emission tomography showed a maximum standard uptake value of 2.5 on the nodule. No significant accumulation was observed in any other areas, and we recommended monitoring of the nodule regularly on CT.

Figure 1.

Preoperative computed tomography scans. (A) Solid nodule at initial referral. (B) A cystic cavity formed 4 months later. (C) Obstructive pneumonia and (D) mucoid impaction in the cystic cavity were observed more than 5 months later.

Follow-up CT 4 months after the first referral showed a thin cystic cavity (Figure 1B). More 5 months later, which indicate 9 months after the first referral, the patient was admitted for obstructive pneumonia due to mucoid impaction of the cystic cavity and connecting bronchus (Figures 1C, 1D). The patient recovered with conservative treatment. Surgical treatment was indicated to prevent recurrent obstructive pneumonia and for histopathologic diagnosis, including possible low-grade malignancy. The patient refused bronchoscopy.

The patient consented to surgery, and thoracoscopic resection of the right basal segment was performed. No malignant cells were found in the specimen resected from the lesion and stump of the basal segment bronchus on the intraoperative frozen section. The perioperative and postoperative courses were uneventful.

The histopathologic diagnosis was localized cystic bronchiectasis. On macroscopic examination, a cystlike dilated bronchiole with a smooth wall connecting to the proximal bronchus was observed (Figures 2A, 2B); the cyst was filled with mucinous discharge (Figure 2C). On microscopic examination, eosinophilic cell invasion of the submucosal layer and hypoplasia of the smooth muscle layer and bronchial glands were observed (Figures 3A, 3 B). The mucinous discharge contained eosinophilic cells and crystallized eosinophil-derived substances: Charcot-Leyden crystals. The proximal connecting bronchus remained patent with cartilages and had a hyperplastic smooth muscle layer and bronchial glands. High infiltration of inflammatory cells (mainly eosinophilic cells), fibrosis, and collapse were observed around the connecting bronchus (Figures 3C, 3D). Subsequent immunohistologic analyses did not reveal any signs of malignancy.

Figure 2.

(A) Macroscopic specimen of the resected right basal segment. (B) Magnified image of localized bronchiectasis and the proximally connected segmental bronchus. (C) Mucinous discharge within the localized bronchiectasis.

Figure 3.

(A) Hematoxylin and eosin staining of the localized bronchiectasis (magnification ×20). Mucinous discharge is contained. Bronchial cartilage, bronchial glands, and smooth muscles are not seen. (B) Infiltrations of inflammatory cells, mainly eosinophils, are seen in the submucosal layer and around the lesion (magnification ×200). (C) Hematoxylin and eosin staining of the connecting bronchus (magnification ×20). (D) Bronchial cartilages (yellow triangle), hyperplastic changes of bronchial glands (orange triangle), and smooth muscles (red triangle) are visible with infiltrations of eosinophils (magnification ×100).

Follow-up CT at 3 years postoperatively showed a pleural effusion near the TVOs, with no recurrence detected. The patient was satisfied with the treatment outcomes.

Comment

Our report suggests that this LB was possibly formed secondary to chronic stimulation by TVOs adjacent to the lung predisposed to allergy and bronchospasm, which was apparent from the patient’s medical and family history and laboratory findings.

The histopathologic examination further supported that the LB was due to dilation of the bronchiole without cartilage by pooled mucinous discharge. This resulted from allergic reactions in the proximal segmental bronchus, such as bronchospasm and increased discharge. The TVOs could have caused the formation of an LB in the adjacent lung. In this area, high infiltration of eosinophilic cells, fibrosis, and collapse were selectively observed. Otake and colleagues³ reported that TVOs could cause focal fibrosis in the adjacent pulmonary tissue. One case report described an LB adjacent to costal exostosis.⁴ Chronic inflammation and fibrosis in the lung around the exostosis were suggested as a cause of the LB.

We avoided lobectomy because of comorbidity, pulmonary function, and low possibility of high-grade malignancy. More limited resection, such as posterior basal segmentectomy, could have been considered. However, we performed basal segmentectomy for the following 2 reasons. First, we carefully attempted to save a sufficient surgical margin because differential diagnoses included adenoid cystic carcinoma,⁵ one of salivary gland–type lung tumors. Adenoid cystic carcinoma is characterized by endobronchial submucosal spread, residual tumor cells at the stump of the resected bronchus, and recurrence at this site.⁵ We had sufficient surgical margins and intraoperatively confirmed the absence of atypical cells at the resected bronchial stump. Second, resecting a relatively large lung volume prevented future compression of the preserved lung by the TVOs. Fortunately, a pleural effusion formed between the preserved lung and the TVOs, and no recurrence was observed. Resections of TVOs have been reported for decompression of the pulmonary vein² and right main bronchus,⁶ which could be better preserved. In addition, thoracoscopic resections of TVOs and their safety have been previously reported.^2,7 However, no indication for TVO resections in our patient could be determined at that time. Therefore, postoperative evaluation should be continued.

In conclusion, we present a case of a resected LB with an extremely rare pathogenesis. Clinicians should be aware of the clinical manifestation and management associated with TVOs.