Lymphangiomas are uncommon lesions of lymphatic channels that are often present at birth and diagnosed mostly (90%) before the age of two years. Lymphangiomas occur exceedingly rarely in adults and few cases are described in the literature. The treatment of choice is complete surgical removal; however, the tumor tends to spread along vital structures therefore sometimes inductive complete surgical removal is impossible. We describe the clinical and pathological features of cystic lymphangioma diagnosed in three adults with lateral neck mass. Clinical examination, ultrasonography, MRI and fine-needle aspiration cytology were performed. We discuss the diagnostic difficulties of this uncommon lesion where in many cases the correct diagnosis is reached only after histopathological investigation of the surgical specimen. Therapeutic options are briefly described. Our cases suggest the need to consider cystic lymphangioma in the differential diagnosis of lateral neck masses in adults, together with adequate imaging and cytological studies to corroborate the preoperative diagnosis.