We present a 36 year old female patient with suspected postpartum advanced metastatic cancer and multiple osteolytic lesions due to which she was referred to the Internal medicine clinic for further diagnostic evaluation. After extensive investigation, it was discovered that the underlying condition was a parathyroid gland adenoma and the patient was treated surgically. Clinicians should note that parathyroid adenoma can mimic metastatic malignant disease, and should make appropriate diagnostic tests that will lead to the correct diagnosis.