The clinical and radiological differential diagnosis of cystic lesions of the submandibular region can be difficult. We report an unusual case of a submandibular salivary duct cyst mimicking an external laryngocele on presentation by appearing to expand on Valsalva manoeuvre, and where computed tomography (CT) scanning was unhelpful in reaching a diagnosis. We present the case, discuss the theories of pathogenesis, and review the literature on the differential diagnosis of cystic lesions in the submandibular region.