SA is a rare malignancy in skin and considered aggressive of all cutaneous angiosarcomas. Predilection for lung metastasis is a feature of this disease, and 90% of all patients were reported to die from pulmonary complications, such as pneumothorax and hemothorax [1,2,3]. Pulmonary metastases of SA exhibit a variety of radiographic appearances, including thin wall cavities, sometimes looking like emphysematous bullae, which make diagnosis only by CT images challenging . In these two patients, preoperative CT images showed thin wall cysts that mimicked emphysematous bullae. Since it is difficult to make a diagnosis only from CT, the pathological tissue diagnosis from the lung or parietal pleura is necessary in terms of clinical management. Generally, chemotherapy and molecular-targeted therapy (pazopanib) were considered as a treatment for metastatic SA; however, the development of pneumothorax and hemothorax made it difficult for patients to receive such a therapy.
In patient A, the development of empyema made it difficult to tell that the parietal pleura had metastatic SA. Apparently, cytology from pleural effusion was not enough for the diagnosis and histological examination of parietal pleura was necessary for diagnosis. Considering the possibility that metastasis in the parietal pleura had already existed in the first surgery, debridement might have caused uncontrolled hemothorax afterward in this patient. Consequently, the suspected uncontrolled infection made it impossible to give him chemotherapy.
In patient B, we obtained the pathological diagnosis of metastatic SA from the resected lung and biopsy of the parietal pleura. We recognized an impressive intrathoracic finding of dark-red spots in the parietal pleura which can be the characteristic lesion of the parietal pleura metastasis of SA before developing hemothorax. To our knowledge, this thoracoscopic finding is reported for the first time in the literature. The patient had hemothorax in the left side after surgery, which was not controlled by repeated pleurodesis despite full expansion of the lung. Deterioration of the general condition was very rapid after the recurrence of pneumothorax and; therefore, we missed a chance to treat with chemotherapy.
In general, pleurodesis using talc or OK-432 is considered effective in carcinomatous pleurisy when the lung is fully expanded by chest tube drainage ; however, it was not successful for pneumothorax and hemothorax in patient B. The mechanisms of pleural metastasis of SA are mentioned in the literature [1, 4]. Namely, (i) excavation of a solid nodular lesion, (ii) infiltration of tumor cells into the walls of preexisting bullous lung tissue, (iii) infiltration of malignant cells into the walls of air sacs and cystic distension through the ball-valve effect of the tumor, and (iv) tumor cell proliferation to form blood-filled cystic spaces that are characteristic of angiosarcoma. The pathological findings from these two patients suggest that the angiosarcomas that spread to the parietal pleura resulted in hemothorax, and the ones that spread to the visceral pleura caused thin wall cysts that consequently developed pneumothoraxes. The extensive infiltration of tumor cells along with the parietal and visceral pleura can make it difficult to manage pneumothorax and hemothorax with pleurodesis even if the lung is fully expanded. Notably, these infiltrating tumor cells did not make nodule or mass lesions, and it was difficult to predict from imaging.