Abstract: Objective　To investigate the characteristics and differential diagnosis of Poland syndrome by Multi-slice Spiral Computed Tomography (MSCT).　Methods　The clinical and imaging data of 9 patients (8 males and 1 female) with Poland syndrome from October 2014 to January 2022 were collected, and their CT features were retrospectively analyzed. The ages of patients ranged from 18 to 83 years old, with an average age of (42±20) years old. . One patient was treated for obvious thoracic abnormality, and the other 8 patients were found accidentally during chest CT examination.　Results　All 9 cases were unilaterally involved, with 5 cases on the right side and 4 cases on the left side. Pectoralis major dysplasia was observed in 7 cases and complete absence in 2 cases. All patients’ pectoralis minor were absent, and the soft tissue of the chest walls were thin and collapsed. The MSCT images showed no normal muscle tissue density in the original pectoral muscle area, and the low-density of subcutaneous adipose tissue was uniform, while the skin of chest wall was continuous. Reconstructed images showed loss of the pectoralis and subcutaneous soft tissue in the affected side, the position of the two papillae was asymmetrical, while the structure of contralateral pectoral muscle was normal. Among them,  multiple malformations of the chest wall was shown on the one patient’s CT, which included pectoralis major dysplasia, pectoralis minor absence, serratus anterior absence, skeletal thoracic collapse, the 3rd and 4th rib dysplasia, nipple dysplasia, thinning of the subcutaneous soft tissue of chest wall, and dextrocardia.　Conclusions　The CT manifestations of Poland syndrome are typical. By combination of axial MSCT images and multiplanar reconstruction, the anatomical structure of chest wall muscles and bones can be clearly shown, which helps to make definite diagnosis and differentiation.

Key words: Poland syndrome, 　Congenital malformation, 　Abnormal thoracic wall, 　Pectoralis major dysplasia, 　Multislice spiral computer tomography (MSCT)