Keywords
neuromucoepidermoid carcinoma - bronchus resection - child
Introduction
Primary malignant bronchial neuroendocrine neoplasms are rarely found in childhood.
Mucoepidermoid carcinoma of the lung, however, is very rare with a reported frequency
of 0.01 to 0.2% of primary lung tumors.[1] Typical symptoms are of a respiratory nature and include wheezing, coughing, dysponea,
and recurrent obstructive pneumonia.[2] Owing to the critical anatomical location of the tumors, their surgical management
presents a considerable challenge and, in all described cases, sternotomies were performed
for surgical access.[3]
[4]
Case Description
A 4-year-old boy was referred to our clinic for further evaluation of wheezing, coughing,
increasing nightly pauses of breath of up to 30 seconds in duration, and progressive
dysponea observed in a sleep laboratory over a 2-month period. The relevant medical
history of the child included an adenoidectomy and tonsillectomy 8 months prior, as
well as an otorhinolaryngological examination 2 weeks earlier. The otorhinolaryngological
examination reported no pathological findings except for pneumonia. On admission,
the child was dyspnoeic with inspiratory and expiratory stridor. A polysomnography
showed peripheral oxygen desaturation of up to 83% and a mixture of obstructive and
central apnoeic episodes. A chest radiograph revealed emphysema of the left lung with
a mediastinal shift. A cardiac malformation was ruled out using transthoracic echocardiography.
A computed tomography (CT) scan of the chest demonstrated an endoluminal broad-based
tumor with incomplete obstruction of the left main bronchus. A rigid bronchoscopy
under general anesthesia was performed to obtain a biopsy prior to surgery ([Fig. 1A]). After receiving the immunohistological diagnosis of neuromucoepidermoid carcinoma,
surgery was planned with cardiopulmonary bypass standby facility. Bronchoscopically
guided selective intubation of the right main-stem bronchus was performed for single-lung
ventilation. The child was placed in a right lateral decubitus position and posterolateral
thoracotomy was performed. Locoregional lymph nodes were dissected and excised for
histomorphological examination. After identification of the left main bronchus, the
vagus nerve and phrenic nerve as well as the left main pulmonary artery, were dissected
and protected. Following mobilization of the left main bronchus from the esophagus,
the left main bronchus was opened by longitudinal incision toward the carina, and
the tumor was detected with involvement of the left main stem bronchus and spread
up to the carina between upper and lower lobe. En bloc resection of two rings of the
main bronchus was performed after meticulous dissection of segmental arteries of the
upper and lower lobes ([Fig. 1B]). The resection margins were checked intraoperatively by frozen section to verify
complete tumor removal. End-to-end anastomosis with reconstruction of the carina between
upper and lower lobe was performed by using 4–0 polydioxanone sutures. Running sutures
were made on the paries membranaceus and interrupted sutures on the cartilaginous
part of the bronchus ([Fig. 1C]). The left pleural space was drained using a 16-French chest tube, the thoracotomy
was closed in standard fashion, and the child was transferred to the pediatric intensive
care unit. The child was extubated 4 hours after surgery. The postoperative course
was uncomplicated. The chest drain was removed on the third day after surgery, and
10 days after the operation the child was discharged from the hospital in excellent
general condition. The final pathological investigation demonstrated negative locoregional
lymph node histology, which excluded metastatic spread and confirmed the diagnosis
of a neuromucoepidermoid carcinoma ([Fig. 1D]). At 6-month follow-up, the child was asymptomatic and tumor free.
Fig. 1 (A) Preoperative rigid bronchoscopy demonstrating a large red sessile tumor (indicated
by triangle). (B) Intraoperative image showing the endoluminal tumor after opening of the left main
bronchus (solid line = left main bronchus; arrow head = esophagus; arrow = tumor,
AO = descending aorta; UL = left upper lobe of the lung). (C) Intraoperative image after bronchus resection and completed end-to-end anastomosis
(arrow head = end-to-end anastomosis; LL = left lower lobe of the lung, AO = descending
aorta). (D) Histomorphological examination using haematoxylin and eosin staining (star = tumor;
arrow = tracheobronchial ring).
Discussion
Neuromucoepidermoid neoplasms are rare tumors of the bronchial tree arising from the
mucous and serous glands of the epithelium and have an age-adjusted incidence rate
ranging from 0.2 to 2/100,000 population/year in both the United States and Europe.[1] Due to the fact that these neoplasms have a wide spectrum of biological activity
and often show malignant behavior, they are now commonly referred to as “bronchial
gland tumors,” rather than “bronchial adenomas,” as they were in the past. “Bronchial
adenomas” include the following three different types of pathological entities: (1)
carcinoid cystic carcinoma, (2) adenoid cystic carcinoma, and (3) mucoepidermoid tumor.
Since 1986, only 15 cases of bronchial mucoepidermoid tumors in children, under the
age of 14 years, have been reported.[2] These slow-growing neoplasms usually manifest with obstruction of the trachea-bronchial
tree, and symptoms are related to their location in the trachea and the main bronchii.
As in the case reported, they mainly cause upper respiratory tract occlusion with
coughing, wheezing, and dysponea, and only rarely produce symptoms like atelectasis
and hemoptysis. In this young child, respiratory distress and relapsing pneumonia
were undiagnosed until a bronchoscopy demonstrated the tracheal obstruction which
was then confirmed by CT scan. Complete surgical resection via a range of different
surgical access routes is the treatment of choice for this subtype of neuro-mucoepidermoid
carcinoma. The key principles of surgery are complete locoregional lymph node removal,
a tumor-free surgical margin at frozen section, and maximum sparing of lung parenchyma
using tracheobronchial resection and reconstructive techniques. Endoscopic resection
has been attempted, but the incidence of local relapse was unacceptably high. Papiashvilli
et al have performed excellent and successful operations via sternotomy, which represents
a difficult operative access to the distal trachea.[3] As stated by the authors, their decision to choose a sternotomy was based on “the
difficulty of ventilating the child” and “the existence of immediate cardiopulmonary
bypass facilities.” We performed a similar operation with a more comfortable surgical
exposure of the lower trachea through a left-sided thoracotomy. We would have employed
extracorporeal circulation via peripheral cannulation of the femoral vessels, if required.
Yu and colleagues from Boston presented their own results with 40 patients between
3 month and 19 years within the past 90 years. Only 34 patients received surgical
treatment, and most of them had major pulmonary resection, none were treated with
isolated bronchial resection, although eight patients were suffering from a carcinoid
and five patients from a neuromucoepidermoid tumor.[5] Therefore, such patients should be treated curatively, whenever possible, with parenchyma-sparing
techniques. In this case report, we demonstrated and discussed the applied surgical
technique the removal of a tracheal neuromucoepidermoid carcinoma in 4-year-old boy
who was successfully treated with a tracheal resection and reconstruction by means
of a left-sided thoracotomy.
Conclusion
In conclusion, these patients should be treated by an interdisciplinary team consisting
of pediatric, thoracic, and congenital cardiac surgeons by applying a curative therapeutic
approach including parenchyma-sparing techniques.
