The paranasal sinuses are closely related to vital structures, and therefore, rhinosinusitis may lead to various dangerous complications. Nasal chondromesenchymal hamartoma is a rare benign lesion of the sinonasal tract in children and adolescents. We report the case of a 15-year-old patient with antibiotic-refractory acute sinusitis in whom a nasal tumor was identified and histopathologically diagnosed as a hamartoma. Therefore, the tumor was removed surgically to alleviate the patient’s symptoms. This case highlights the necessity of investigating the underlying cause if conventional treatment fails to resolve a mild disease like acute sinusitis. To the best of our knowledge, this is the first reported case of a chondro-osseous respiratory epithelial adenomatoid hamartoma presenting with acute sinusitis.