Shim WS et al.: Parathyroid Adenoma Presenting as a Massive Hematoma 47 A B Fig. 1. The CT scan shows cervical hematoma (arrow), obliterating the fat plane between the right thyroid, right common carotid artery (A). The ultrasonography shows a 2 cm sized heterogenous echogenic mass in the right infrathyroid region (B). Fig. 2. The follow-up CT scan at 3 weeks. Cervical hematoma shown in previous CT scan is nearly resolved, and there is a 2 cm sized periph- eral rim enhancing cystic mass in the right tracheoesophageal groove near the thoracic inlet. The specific cause of hematoma was not identified and conser- vative management with intermittent sono-guided aspiration was performed without specific events. After 3 weeks, her neck swelling and bruise were resolved and a follow-up CT scan revealed a peripheral rim-enhancing cystic lesion in the right tracheoesophageal groove (Fig. 2). We performed an exploration of the neck through the anteri- or approach. An organized hematoma and 3 cm sized, dark brown colored cystic mass was found in the right tracheoe- sophageal groove and posteroinferior aspect of the right thyroid gland, compressing the right recurrent laryngeal nerve (Fig. 3). Fig. 3. Intraoperative a ovoid cystic mass (arrow) in the right tracheoe- sophageal groove compressing the right recurrent laryngeal nerve (asterisk). The mass was dissected out with preservation of the right recur- rent laryngeal nerve. The histologic examination showed that the mass was mainly composed of fairly uniform, polygonal chief cells with small, centrally placed nuclei; this was all compatible with parathyroid adenoma (Fig. 4). Postoperative course was uneventful and vocal cord paresis was resolved during one month after the surgery. DISCUSSION Spontaneous hemorrhage of the parathyroid gland may occur due to parathyroid adenoma, parathyroid hyperplasia or parathyroid cyst. The hemorrhage may be localized within the parathyroid gland, but it is often presented as extracapsular hemorrhage. The