Surgical case reports · 2026
A Case of Exuberant Type 2 Pneumocyte Hyperplasia in a Young Man with Recurrent Spontaneous Pneumothorax: A Diagnostic Pitfall.
Клинический случайСтатьяНазвание и аннотация: Перевод в очереди
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Hirai Fumihiko, Kato Seiya, Nagano Taichi, Fujimoto Yoshiaki, Hirose Kosuke, Wang Huanlin, Okadome Jun, Honboh Takuya, Harada Noboru, Ito Hiroyuki, Hayashi Takuo, Sadanaga Noriaki
Аннотация
INTRODUCTION: Exuberant type 2 pneumocyte hyperplasia is a rare histopathological pattern of reactive epithelial change associated with spontaneous pneumothorax, in which preoperative clinical findings and radiological images usually show only nonspecific bullae and blebs. However, it is difficult to differentiate this entity from other conditions, especially pulmonary epithelial tumors, creating significant diagnostic pitfalls in postoperative histopathological evaluation.
CASE PRESENTATION: A 28-year-old man presented with recurrent left-sided spontaneous pneumothorax. Preoperative chest CT revealed subpleural blebs at the left lung apex and in the left lower lobe, without pulmonary nodules or mass lesions. Video-assisted thoracoscopic bullectomy was performed to remove 2 lesions. On gross pathological examination, bullae were observed just below the pleura, consistent with the cause of pneumothorax. In addition, histological examination revealed multiple nodular lesions several millimeters in size within the pulmonary parenchyma, and the airspaces were collapsed due to proliferation of bronchioloalveolar epithelium and accumulation of alveolar macrophages. Despite apparent cytological atypia and high proliferative activity demonstrated by immunohistochemistry (Molecular Immunology Borstel-1 index: 60%), the distinctive histopathological features supported the diagnosis of exuberant type 2 pneumocyte hyperplasia rather than primary or metastatic neoplasia. The patient has been well for over a year after surgery without recurrence.
CONCLUSIONS: Spontaneous pneumothorax is a common condition, but it can also occur secondary to tumors. It is important to differentiate exuberant type 2 pneumocyte hyperplasia from lung tumors, especially atypical adenomatous hyperplasia and adenocarcinoma. Careful histological examination of resected surgical specimens is essential even in cases suspected of primary spontaneous pneumothorax without radiologically apparent tumor-like lesions, to avoid misdiagnosis and overtreatment.
CASE PRESENTATION: A 28-year-old man presented with recurrent left-sided spontaneous pneumothorax. Preoperative chest CT revealed subpleural blebs at the left lung apex and in the left lower lobe, without pulmonary nodules or mass lesions. Video-assisted thoracoscopic bullectomy was performed to remove 2 lesions. On gross pathological examination, bullae were observed just below the pleura, consistent with the cause of pneumothorax. In addition, histological examination revealed multiple nodular lesions several millimeters in size within the pulmonary parenchyma, and the airspaces were collapsed due to proliferation of bronchioloalveolar epithelium and accumulation of alveolar macrophages. Despite apparent cytological atypia and high proliferative activity demonstrated by immunohistochemistry (Molecular Immunology Borstel-1 index: 60%), the distinctive histopathological features supported the diagnosis of exuberant type 2 pneumocyte hyperplasia rather than primary or metastatic neoplasia. The patient has been well for over a year after surgery without recurrence.
CONCLUSIONS: Spontaneous pneumothorax is a common condition, but it can also occur secondary to tumors. It is important to differentiate exuberant type 2 pneumocyte hyperplasia from lung tumors, especially atypical adenomatous hyperplasia and adenocarcinoma. Careful histological examination of resected surgical specimens is essential even in cases suspected of primary spontaneous pneumothorax without radiologically apparent tumor-like lesions, to avoid misdiagnosis and overtreatment.