Brown Tumors And The Atypical Parathyroid Adenoma

Objective: Present a case of an atypical parathyroid adenoma with extreme clinical features and discuss the uncertainties in differentiating between benign and malignant masses. Methods: The clinical, laboratory, and imaging findings are presented with a literature review of current methods for distinguishing parathyroid adenoma from carcinoma. Results: A 37-year-old man presented to his primary care physician with worsening bone pain and increasing irritability over the span of 2 years. Laboratory evaluation showed a highly elevated serum calcium (15.7 mg/dL) and parathyroid hormone (1,790 pg/mL). Computed tomography revealed multiple brown tumors throughout his body and a 2.8-cm mass in the tracheoesophageal groove. Fine-needle aspiration of the 2.8-cm mass was suggestive of a neoplastic/hyperplastic process but could not definitively identify thyroid or parathyroid cells. The patient underwent surgery 2 weeks after initial diagnosis. Because intra-operative histopathology was suggestive of parathyroid adenoma, simple parathyroidectomy was performed. The final pathology report, however, demonstrated atypical features that were suggestive but not diagnostic of parathyroid carcinoma. The patient was ultimately given a diagnosis of atypical parathyroid adenoma but continues to be monitored for signs of malignancy. Conclusion: Parathyroid adenoma and carcinoma differ greatly in their disease progression and standard of care. Fine-needle aspiration should be avoided if high clinical suspicion for a parathyroid mass. While histopathology is the mainstay for differentiating between parathyroid adenoma and carcinoma, it may fall short for tumors with ambiguous features. Literature review suggests that immunohistochemistry may be an increasingly valuable tool in differentiating between benign and malignant parathyroid masses.