Objective: Present a case of an atypical parathyroid adenoma with extreme clinical features like multiple brown tumors and discuss the uncertainties in differentiating between a benign and malignant entity. Background: The atypical parathyroid adenoma is purely a histological diagnosis. It is a parathyroid tumor with atypical histological features different from an adenoma but not similar enough to be considered as a carcinoma. It has an uncertain malignant potential. Case description: We report the case of a 48-year-old woman, who presented with multiple swellings all over the bony areas of her body. Positron emission tomography computed tomography (PET CT) showed a fluorodeoxyglucose (FDG) avid lesion in the right thyroid lobe with multiple skeletal lesions. Further evaluation revealed hypercalcemia following which a Sestamibi scan was done. Diagnosis of primary hyperparathyroidism (PHPT) with right inferior parathyroid adenoma and associated multiple brown tumors in hypercalcemic crisis was made. The patient underwent focused right inferior parathyroidectomy and postoperatively, iPTH and calcium levels dropped significantly. The histopathological examination of the removed tissue concluded to be an “atypical” parathyroid adenoma. The atypical parathyroid adenoma is a very rare tumor, and the diagnosis is still a challenge, the outcome of patients is not well known yet, therefore close surveillance is important and must be done regularly.