[Simple juxtathyroid cyst. Analysis of the possible origin of the lesion]

We report a 34 years old female who presented with a simple juxtathyroid cyst. Its content was translucent with a mPTH concentration 30 higher than in blood. This finding lead to the suspicion of a parathyroid cyst; however there were no laboratory evidence of hyperparathyroidism. Two years later and after repeated needle drainages, a surgical cystectomy was made. The immunohistochemical study of the samples was intensely positive for synaptophysin, a parathyroid tissue marker. Surprisingly, thyroglobulin was also found in some cyst wall cells.