[Simple thyroid cyst]

Simple or true thyroid cysts are very rare. We only have found one case in which colorless and acellular transparent fluid has been found by means of the fine needle aspiration puncture (FNAP). We report the case of a 33 year old female who first presented with a rapidly growing thyroid nodule. The thyroid scintigraphy revealed the existence of a cold nodule and the ultrasonography showed a lesion having a cystic appearance. The FNAP was performed and was both diagnostic and therapeutic in this case.