Parathyroid tumors can be divided in adenomas and carcinomas, usually detected by hypercalcemia. We report a case of parathyroid adenoma in a young man, who complained of a pressure in the left neck region. Physical examination revealed a firm mass in the neck, without lymphnodes. Although Ca (9.7 mg/dl), phosphorus (3.3 mg/dl) and intact-PTH (49 pg/ml) were normal, imaging techniques (computed tomography scan and sestamibi substraction scan) suggested that the mass could arise from the parathyroid gland. Histology and immune staining for chromogranin and parathyroid hormone confirmed the parathyroid nature of the mass. Histological criteria defined the lesion as an atypical parathyroid adenoma. We review the pathology, diagnosis and treatment of parathyroid adenomas in its non-secreting atypical form.