Brown tumor (BT) is caused by altered metabolism of calcium resulting from hyperparathyroidism (primary or secondary). The most common cause of hyperparathyroidism is isolated parathyroid adenoma (PA), and the most common symptoms are hypercalcemia related. BT is considered as a late manifestation of PA and usually diagnosed after surgical treatment of the bony lesion. Fine-needle aspiration cytology (FNAC) is a cheap, easy, and less traumatic procedure and should be performed in all lesions wherever possible as unnecessary surgeries may be avoided. We here report a rare case of PA presenting primarily as BT and diagnosed on FNAC.