We reported a very rare case of postoperative visceral subpleural hematoma. Diagnosis was difficult and surgery was required. Subpleural hematoma is classified as either parietal subpleural hematoma or visceral subpleural hematoma. Hematomas of the parietal pleura account for most reports of subpleural hematoma. Visceral pleural hematoma was reported in three of 98 patients who underwent preoperative CT-guided hook wire localization [
5]. Visceral pleural hematoma was seen in 1 case among 138 pleural complications in lung transplant recipients [
6]. Traumatic false aneurysm of the descending aorta that ruptured into the right thoracic cavity has also been reported to result in visceral pleural hematoma [
7]. Given these findings, visceral subpleural hematoma is rare and has also been reported as pulmonary pseudocyst or cavitary pulmonary lesions [
1]. Most cases were reported as traumatic pulmonary pseudocyst and contained fluid and air [
1‐
3]. Such lesions are caused by laceration of the visceral pleura in lung injuries after blunt chest trauma, and are most often seen in children or young adults. Because the thorax is elastic, the visceral pleura remains intact, and the parenchyma is easily injured [
2]. Although these cases have been reported after trauma, those following lung resection are very rare. Hematoma in the intersegmental plane has been reported after segmentectomy, where the surgeon attached the borders of the intersegmental plane to each other [
8]. To the best of our knowledge, no cases of postoperative subpleural hematoma have been described in the English literature. A case of visceral subpleural hematoma after lobectomy for rapidly growing metastatic lung tumor has been reported in Japanese [
9]. Visceral subpleural hematoma in this case was revealed on the interlobar surface near the staple line. However, visceral subpleural hematoma in our case appeared in the subpleura of the basal lung, and was not touched in the first operation. In our case, edoxaban was started and a dead space with an air-fluid level subsequently appeared on chest X-ray. We considered that the small hematoma appeared under anticoagulation due to pressure changes under diaphragmatic movements such as cough, and progression of laceration, trapping air and increasing in size. On the other hand, pulmonary visceral hematoma may have arisen from pulmonary pseudocyst, in which case the cause cannot be identified.
The chest X-ray appearance of visceral subpleural hematoma sometimes resembles that of lung abscess, cavitating tuberculosis, or bronchial carcinoma with cavitation in adults [
3]. In particular, computed tomography may be helpful in diagnosing traumatic pulmonary pseudocyst [
1]. Treatment usually involves conservative therapy, as the cyst contents are excreted or absorbed spontaneously. Surgery is required if the pseudocyst develops persistent infection [
2]. Our case could not be differentiated from abscess. Moreover CT-guided drainage was also difficult. Because we thought that the point of puncture was limited and the insertion of a puncture needle was difficult on account of the cyst with elastic feature. Surgery proved useful as a diagnostic and therapeutic procedure. There may be the other opinion such as the surgical procedure which covers the diaphragmatic surface of the lower lobe with tissue adhesives without running suture after removing the peel of the visceral pleura. However, we thought that a running suture could prevent the visceral pleura peeling off more, and we selected the procedure.