대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Mesenchymal hamartoma of the pleura (Extrapulmonary hamartoma)

Radiologic Findings

Pre and post-contrast enhanced chest CT scans (Figs.1-4) show huge mass lesion with mild enhancement and internal fat density in the right hemithorax. On coronal and sagital reconstructed images (Fig. 5 and 6), the mass lesion abutted to the esophagus of the mediastinum, and is combined with pleural effusion. On initial chest radiograph performed at other hospital (Fig. 7), double contour of increased opacity is noted in the right retrocardiac area, suggesting a mass lesion. After 15 months, follow-up chest radiograph performed at our hospital (Fig.8) shows homogenous increased opacity in right middle and lower lung zones.

Brief Review

Pulmonary hamartomas are considered to be true mesenchymal tumors. They account for approximately 8% of all pulmonary tumors (1) and 75% of all benign pulmonary tumors. There are the two types of pulmonary hamartoma: parenchymal tumor and endobronchial tumor.
Endobronchial hamartomas are relatively rare, accounting for 1-20% of all pulmonary hamartomas, and are more likely to cause symptoms related to airway obstruction than other hamartomas (2). Most hamartomas are located in peripheral areas; they may be asymptomatic, and their growth is generally slow (approximately 3 mm per year) (3). The underlying cause of a hamartoma is unclear, although chronic inflammatory irritants are a possible etiological factor (4).
In our present case, at surgery, the mass lesion proved to develop from the mediastinal aspect of the right visceral pleura, made right inferior pulmonary ligament stretched, and located in the pleural cavity. The mass did not invade the parietal pleura and diaphragm. At the medial aspect of the tumor, mild adhesion with esophageal muscle layer was noted, probably due to mass effect of the tumor. On pathologic findings, the tumor was composed of mature cartilage, smooth muscle and adipose tissue and had no malignant cells.
Like a present case, the pleural origin seem to be rare that only four cases have been reported (5,6,7,8). They seem to be developing from the hilar, mediastinal, interlobar region of visceral pleura. The unusual growth pattern may be caused by ectopic bronchial tissue underneath the visceral pleura, developing toward the pleural cavity (8).
Treatment is usually conservative with regular chest roentgenograms during the follow-up. However, when malignancy cannot be ruled out by this procedure or when the nodules are rapidly growing, surgery should be considered.

References

1. Bateson EM. Histogenesis of intrapulmonary and endobronchial hamartomas and chondromas (cartilage containing tumors): a hypothesis. J Pathol 1970;101:77-83.
2. Cosio BG, Villena V, Echave-Sustaeta J, de Miquel E, Alfaro J, Hernandez L, et al. Endobronchial hamartoma. Chest 2002;122:202-5
3. Whyte RI, Donington JS. Hamartomas of the lung. Semin Thorac Cardiovasc Surg 2003;15:301-4.
4. Salminen US. Pulmonary hamartoma: a clinical study of 77 cases in a 21-year period and review of literature. Eur J Cardiothorac Surg 1990;4:15-8.
5. Kaptanoglu M, Nadir A, Yildiz E, Elagoz S. Pulmonary hamartoma, a rare presentation. Eur J Cardiothorac Surg 2001;20: 1031.
6. Tomiyasu M, Yoshino I, Suemitsu R, Shoji F, Sugimachi K. An intrapulmonary chondromatous hamartoma penetrating the visceral pleura: report of a case. Ann Thorac Cardiovasc Surg 2002;8:42-4.
7. Teramoro K, Suzumura Y. Multiple pulmonary hamartomas enetrating the visceral pleura: report of a case. Surg Today 007;37:1087-9.
8. Tetsuya Endo,Shunsuke Endo, Tsuyoshi Hasegawa, Kenji Tetsuka, MD Shinichi Yamamoto, Shinichi Otani, Yoshihiko Kanai, Yasuhiro Tezuka. Extrapulmonary hamartoma. Gen Thorac Cardiovasc Surg (2011) 59:209-211.

Keywords

pleura, benign tumor,