*_Poland syndrome_* can cause breast hypoplasia, which means the breast may be underdeveloped or absent. It's a rare congenital disorder that affects the chest, shoulder, arm, and hand. Symptoms Hypoplasia or absence of the breast or nipple Scarcity of subcutaneous tissue Absence of the costosternal portion of the pectoralis major muscle Absence of the pectoralis minor muscle Aplasia or deformity of the costal cartilages or ribs Alopecia of the axillary and mammary region Treatment Breast reconstruction: Tissue expansion can be used to stretch the contracted skin and potentially lower the raised nipple A latissimus muscle flap can be used with or without a permanent implant to reconstruct the breast Lipomodelling can be used to correct breast and chest wall deformities Other features Missing or underdeveloped muscles on one side of the body Abnormal ribs that sometimes can lead to breathing problems Hand abnormalities such as short or fused fingers Shortened forearm bones Heart, lung, or kidney problems.