Abstract: PIK3CA-related overgrowth spectrum (PROS) is a rare condition characterized by disproportionate overgrowth of head, neck, trunk, or extremity, caused by PIK3CA gene mutation. This condition has negative impact on the physical appearance, functions, and psychosocial well-being of the patients. The condition causes social and economic burden, too. The gold standard for the diagnosis of PROS is the genetic testing using somatic tissue, but detecting low-level mosaic mutations of PIK3CA gene remains a challenge. There is no specific treatment now. Supportive management including surgery and other interventions have limited effects in improving cosmetic outcome and functions. Multidisciplinary collaboration is the key to the success of managing PROS. Targeted gene therapy is promising in improving the outcome for patients with severe PROS. Patients diagnosed with negative genetics test by the clinical measures are often ineligible for novel gene therapy. This article reviews the clinical manifestations, diagnosis, and treatments of PROS, aiming to improve the current understanding of this rare condition.