Endoscopic Resection of Middle-Ear Lymphatic Malformation in a Child

An 8-year-old boy was referred to our otolaryngology department with a 3-year history of slowly progressive hearing loss in the left ear. He reported no otorrhea, fullness sensation, dizziness, or tinnitus; he also did not report any history of trauma, recurrent otitis media, or prior otologic surgeries. He had visited the otolaryngologic clinic of a local general hospital, where his pure tone audiogram demonstrated a mixed type hearing loss in the left ear with an air conduction of 70 dB and an air–bone gap of 25 dB, and his tympanogram was type A in both ears. In our otomicroscopic examination, the external ear canals and tympanic membranes of both ears were found to be normal. Complete physical examination, including a motor function test of the facial nerve, revealed unremarkable results, without any syndromic presentation. Noncontrast high-resolution axial computed tomography (CT) scanning of the temporal bone revealed a 5 × 4 × 3 mm³ soft tissue mass in the medial wall of the left middle ear abutting the promontory (Figure 1A). Coronal CT demonstrated a dysplastic left stapes, and a suspicious defect in the left vestibule (Figure 1B). Subsequent hearing test before surgery revealed a left-side scaled out sensorineural hearing loss. The patient underwent an endoscopic exploratory tympanotomy through a transcanal approach (Figure 2A) and a complete excision of the left middle ear cystic mass (Figure 2B). No significant bleeding was encountered. However, a defect in the vestibule with perilymph leakage was identified after tumor removal. The defect was obliterated with a soft tissue autograft. The histopathology (Figure 3) exhibited a lymphatic malformation (LM). On postoperative day 2, the patient had no symptoms of imbalance and was discharged. He was followed continually for 24 months after the resection with no signs of recurrence. However, follow-up audiometry showed that the boy’s hearing did not improve even after the surgery. Written informed consent was obtained from the patient and his parents. The Ethics Committee of the Cardinal Tien Hospital approved the case report (CTH-109-3-7-001).

Figure 1.

A, Noncontrast high-resolution coronal temporal bone computed tomography image demonstrating a soft tissue mass in the left middle ear (arrow). B, Axial view of the same lesion (arrow).

Figure 2.

A, Intraoperative endoscopic view before tumor removal, showing a cystic mass (arrow) abutting the long process of the incus (arrowhead) and the chorda tympani nerve (asterisk). B, Intraoperative endoscopic view after tumor removal, showing a defect in the vestibule with perilymph leakage (arrow), the long process of the incus (arrowhead), and a hypoplastic round window (asterisk).

Figure 3.

Histopathology. A, Lymphatic malformation with irregular, folded, and cystic dilated fibrous wall lined by endothelial cells. The lumens contain no red cells. (H and E, 200× magnification). Immunohistochemical examination of the lining cells: positive for D2-40 (B, ×200 magnification), negative for CD31 (C, ×200 magnification), and smooth muscle actin (SMA)-stained muscle fibers in the stroma (D, ×200 magnification). H and E indicates hematoxylin and eosin.

Lymphatic malformations—sometimes called lymphangiomas—refer to benign abnormal growth of the lymphatic vessels, typically diagnosed in the pediatric population. ¹ Lymphatic malformation is considered to be a pathological process involving the development or drainage of the lymphatic structures, rather than a neoplastic change. ² Congenital LMs results from developmental sequestration at different stages of lymphangiogenesis, whereas acquired LMs occur due to minor trauma, infection, chronic inflammation after surgical procedures or due to lymphatic drainage obstruction. ^1,3 Regardless of the theoretical cause, the pathological inference of the LM is the failure of the lymphatic vessels to drain their contents into the venous system. ³ Lymphatic malformation symptoms and severities differ with its size and location. These lesions, regardless of size, can potentially cause functional impairment of neighboring structures. Rarely, LMs may remain undetected over time, and come to medical attention only after development of symptoms. ² Lymphatic malformations involving the middle-ear cavity are extremely rare, with only 3 reported cases in the English literature. ^{4 -6} Unilateral progressive hearing loss is the most commonly presented symptom; tinnitus, aural fullness, and facial nerve paralysis have also been reported. We present a unique case of middle-ear LM with a perilymph leakage. Rapidly worsening unilateral sensorineural hearing loss was characteristic in this patient. Treatment modalities for the head and neck LMs include observation, surgery, sclerotherapy, and medical management. Although a percentage of these lesions regress spontaneously, ^1,7,8 Hassanein et al reported that children with LMs had an 84.7% risk of progression before adulthood and 95.3% during their lifetime. ⁹ Thus, the treatment of choice for symptomatic LMs located in the middle ear is surgical excision. ^{1 -3} All reported cases of middle-ear LMs have involved a surgical procedure as a diagnostic or treatment modality, such as a postauricular-transcanal approach exploratory tympanotomy ⁵ and a tympanomastoidectomy. ^4,6 However, we used an endoscopic transcanal excision that resulted in the unique presentation of a localized middle-ear mass in our patient. Lymphatic malformation prognosis after excision depends on its location and its effect on the nearby structures. In the present case, despite immediate surgical repair of the vestibular defect, the hearing did not improve after the procedure. In conclusion, we presented a rare case of the middle-ear LM, successfully resected with an endoscopic approach. Although middle-ear LMs may be extremely rare and histologically benign, their occurrence along with the vestibular abnormalities can cause irreversible hearing loss as reported here. Therefore, these lesions warrant early recognition and timely management.