Cystic Hygroma in a Tactical Aviator: A Case Report

Military Medicine, Dec 2004 by Oakes, Michael J, Sherman, Bret E

Cystic hygroma of the neck is a benign, congenital tumor of lymphatic origin rarely seen in adults, with approximately 100 cases presented in the literature. The etiology of this lesion is poorly understood, with spontaneous occurrence, upper respiratory infection, or trivial trauma being suggested. We present a recent unique case report of an adult male tactical aviator who experienced a progressively enlarging cystic hygroma of the neck over a 2-week period without history of infection or obvious trauma. This case is unusual in that there may have been an element of continuous microtrauma to the area given the individual's occupation and required flight head gear. A successful surgical dissection and removal of the cystic hygroma was performed. A discussion and brief literature review of cystic hygroma in adulthood is presented.

Introduction

Cystic hygroma is a benign developmental tumor of lymphatic origin and is considered to be a relatively rare lesion. It accounts for 5 to 6% of benign tumors and 1.2% of all tumors benign and malignant.12 The neck is the most common site, where they account for 4% of benign cervical masses.3 Approximately 90% of cystic hygromas are present by age 2, with 95% presenting by adolescence.2,4,5

Although the exact etiology is unknown, obstructive or proliferative disorders of lymphatic embryogenesis are suspected to result in cystic hygroma formation. Usually, the tumor is slow growing, occasionally stable, and rarely undergoes spontaneous regression.6 Surgical excision is the treatment of choice by most authors.1 There are 100 adult cases of cystic hygroma described in the literature worldwide, the last of which was written by Bret E. Shermanin 2001.

Case Report

A healthy 30-year-old Australian Caucasian male tactical aviator presented to the Aviation Medicine Department at the Lemoore Naval Air Station Branch Medical Clinic with a 1 -week history of a painless, enlarging mass under the left mandible he noticed while shaving. At this point in his career, he had been flying high G force aircraft for 7 years, with some of the highest exposure being for the 2 weeks preceding presentation during a highly tactical portion of the aircraft syllabus. The mass was painless and showed no signs of inflammation. He admitted to no obvious neck trauma, recent upper respiratory infections, or any previous history of neck masses as an adult or child. He denied any dysphagia, dyspnea, odynophagia, weakness, or dysthesia of the face or upper extremities. There was also no hoarseness, change in voice, or increase in voice clearing. His main complaint, aside from the swelling, was a fullness and restriction of cervical rotation to the left along with an improper fitting of his oxygen mask. His past medical and surgical history, family history, and review of systems were unremarkable.

On examination, a soft, fluctuant, nontender, somewhat defined mass measuring approximately 5 � 7 cm could be palpated from the sternocleidomastoid muscle and the angle of the mandible across the thyroid cartilage to the submandibular area on the right side. The mass was without bruit or thrill, with some submandibular lymphadenopathy; the remainder of the neck examination was normal.

The patient was observed without treatment for 1 week followed by a 2-week course of antibiotics as the swelling persisted, and, in fact, worsened. After failure of antibiotic therapy with continued worsening, other avenues of the differential diagnosis were pursued to include congenital anomalies, metabolic conditions, and neoplasm. A computed tomography (CT) scan of the neck with contrast was obtained, revealing a large, low attenuated accumulation just below the left mandible with an enlarged submandibular lymph node. The thick-walled lesion wrapped beneath the mandible and had associated streaking in the pericystic fat planes (Fig. 1). A diagnostic and therapeutic aspiration with an 18-gauge needle was performed, and fluid cultures were negative. The diagnosis at this point was most consistent with cystic hygroma and the patient was scheduled for surgical excision.

The patient underwent total excision without decompression or violation of the cyst's integrity via a left modified neck dissection with continuous nerve monitoring. The hygroma was found to attenuate itself into the pterygoid fossa to the skull base. Anteriorly, it presented to the mentum and across the midline, to the contralateral floor of the mouth. It also extended into the neck and was closely approximated with the left submandibular gland. Submandibulectomy with complete supraomohyoid neck dissection to remove the lesion and associated lymphatics was required. Pathologic examination revealed the surgical specimen to measure 7 � 4 � 4 cm, containing cystic lesion and submandibular salivary gland. It weighed 29 g and contained brownish red fluid. Microscopic evaluation showed the mass to be a complex conglomeration of lymphatic spaces that were cystically dilated. These were lined by a single layer of benign endothelial cells, some of which were filled with proteinaceous fluid, consistent with cystic hygroma (Fig. 2). There were no pathologic alterations of the submandibular gland or lymph node tissues. There was no histologie evidence of dysplasia or malignancy.