Contributed by James T. Edinger, MD and Sarangarajan Ranganathan, MD
The patient is a thirteen year-old female with a history of asthma who presented to the emergency department with a three-week history of an enlarging right neck mass. When the mass was first noticed, it was small and felt to be lymphadenopathy. In the subsequent weeks, it rapidly enlarged and became more painful. She had no fever and no signs or symptoms of upper respiratory tract infection. There was no respiratory compromise or dysphagia. She reported no recent weight loss. Physical examination showed her to be afebrile with normal vital signs. There was a 4 x 3 cm mildly tender, firm mass at the anterior border of the right sternocleidomastoid muscle at the level of the hyoid bone. No stridor was appreciated.
Based on the history and physical exam findings, an infectious process or abscess was felt to be unlikely. A complete blood count, uric acid level, and lactate dehydrogenase level were performed to assess for possible lymphoma. These tests were all within normal limits. A computed tomography scan of the neck was performed to further evaluate the mass. It revealed a cystic mass in the posterior aspect of the right carotid space extending from the level of the oropharynx down to the level of the thyroid gland. The mass measured approximately 4.5 cm in the anteroposterior axis by 3.6 cm in the mediolateral axis. A few septations were present. The mass displaced the right common carotid artery, carotid bifurcation and internal carotid artery anteriorly. The right internal jugular vein was displaced laterally and compressed by the mass. There was also mass effect on the airway. The lesion demonstrated minimal peripheral enhancement (Figures 1, 2 and 3).
The patient was seen in the otolaryngology clinic several days later, and resection of the mass was recommended. Elective resection was performed approximately one and a half months later. Intraoperatively, the mass was identified anterior to the right sternocleidomastoid muscle and was dissected from carotid artery and jugular vein. It was removed without complication. The patient was discharged the following morning.
Gross examination of the resected specimen revealed a 7 x 4.4 x 2.3 cm, slightly lobulated and sharply circumscribed, gray to tan mass with a small amount of attached tan soft tissue. The cut surface demonstrated two cystic spaces, the largest measuring 3.7 cm in greatest dimension. The cystic cavities were filled with soft, yellow, gelatinous material. The cyst wall was firm and smooth with fairly uniform thickness (Figure 4).
Histologic examination of the specimen revealed a multicystic lesion with a thick fibrous wall and homogeneous, eosinophilic contents containing numerous cholesterol clefts (Figure 5). Focally, the cystic spaces had a flatted, simple cuboidal lining (Figure 6); however, much of the cyst lining was replaced by pigment-laden histiocytes, multinucleated giant cells, and numerous cholesterol clefts (Figure 7). There was a portion of lobulated lymphoid tissue with dilated and congested blood vessels immediately adjacent to the cystic spaces (Figure 8). The lymphoid tissue was comprised of uniformly small, round lymphocytes without atypical features. Higher powered examination of this tissue revealed numerous epithelial structures reminiscent of Hassall's corpuscles (Figure 9). The lymphoid tissue focally extended along and into the fibrous wall of the cystic cavities (Figures 10 and 11).