Yonago Acta medica 2009;52:91–94

Neurogenic Dumbbell Tumor Resected byCombined Posterior and Thoracoscopic Approaches
Makoto Wakahara, Hiroshige Nakamura*, Ken Miwa*, Yoshin Adachi*, Shinji Fujioka*,Tomohiro Haruki*, Yuji Taniguchi*, Masako Hayashibara†, Hideki Nagashima† andRyota Teshima†
Post-Graduate Clinical Research Center and *Division of General Thoracic Surgery, Tottori
University Hospital and †Division of Orthopaedic Surgery, Department of Medicine of Sensory
and Motor Organs, School of Medicine, Tottori University Faculty of Medicine, Yonago 6838504 Japan

The patient was a 51-year-old female with a chief complaint of numbness of the right thigh.
A dumbbell tumor compressing the 11th thoracic spinal cord was present in the posterior
mediastinum on chest computed tomography and myelography. In surgery, the tumor in
the spinal canal was resected by a posterior approach, and the residual tumor was completely excised by thoracoscopic surgery. The tumor measured 78 48 mm, and histopathologically diagnosed as schwannoma. The surgical procedure for neurogenic dumbbell tumors should be decided based on Eden’s classification. For types II and III, such as
this patient, excision of the tumor in the spinal canal should be performed to avoid spinal
cord damage, followed by thoracoscopic complete resection. Thoracoscopic surgery wasapplicable even though the tumor was large.
Key words: dumbbell tumor; neurogenic tumor; posterior approach; thoracoscopic surgery

Neurogenic tumors account for 12% to 21% ofmediastinal tumors, and many are associated with
the intercostal and sympathetic nerves (Ozawa etal., 2007). About 10% of neurogenic tumors invade the spinal canal (Cardillo et al., 2008), andare called dumbbell tumors because of their shape.
Surgery is the first-choice treatment, but the surgical procedure for this type is difficult because it
expands outside and inside the spinal canal via theintervertebral foramen. There are posterior andthoracic approaches employed individually or in
combination, depending on tumor advancement(Nakamura et al., 2000; Grillo et al., 2003; Payeret al., 2006; Agrawal et al., 2008). We resecteda large intrathoracic neurogenic dumbbell tumor
classified type III on Eden’s classification (Eden,1941) by combined posterior and thoracoscopic approaches, and achieved a favorable outcome.

Patient Report
The patient was a 51-year-old female in whom amass was discovered on chest computed tomography (CT) in 2000 during a medical checkup, anddiagnosed as a thoracic spinal tumor by findings onchest magnetic resonance imaging (MRI). Since
the tumor size had not changed from when chest
CT was done in 1998, and symptoms were absent,
course observation was selected. Since the tumor
started to grow in 2003, and numbness appeared in
the right thigh in April 2007, surgery was sched-Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging91M. Wakahara et al.

uled. A 60-mm Eden III dumbbell tumor waspresent at the 11th thoracic vertebral level on chest
CT (Fig. 1) and chest MRI (Fig. 2), and the thoracic
spinal cord was markedly compressed by the tumor
on CT myelography (Fig. 3). In surgery, initially,laminectomy was performed by a posterior approach in the prone position, and the tumor in thespinal canal was resected. No tumor invasion in
the dura mater was noted. The position was thenchanged to the lateral, and thoracoscopic surgery
using 4 ports was performed. The tumor communicating with the 11th intercostal nerve was present(Fig. 4). The nerve was separated, and the tumor
was completely excised. The tumor measured 78
48 mm (Fig. 5), and histopathologically diagnosed
as schwannoma (Fig. 6). The symptoms resolved
after surgery, the recovery was smooth, and the patient was discharged. No recurrence has occurred
as of 1 and a half years after surgery.

Fig. 1. Chest CT shows an approximately 60-mm in diameter dumbbell tumor (arrow) at the 11th thoracic vertebral level.

Discussion
Regarding the incidence of neurogenic dumbbell
tumor, Ozawa et al. observed 118 dumbbell tumors
among 674 neurogenic tumors (18%): the incidence
is not low, and surgerical methods less invasive
to prevent postoperative deformity are necessary(Ozawa et al., 2007). Generally, there are thoracic
approaches, such as thoracotomy and thoracoscopic
surgery, and posterior approaches, such as leminectomy and costotransversectomy, and these are employed individually or in combination (Nakamuraet al., 2000; Grillo et al., 2003; Payer et al., 2006;
Agrawal et al., 2008). Surgical procedure should
be decided based on tumor extension, for which
Eden’s classification (Eden, 1941) is used. Resection of intrathoracic tumor by a posterior approach
alone is difficult in some patients, and the frequency of spinal cord disorder associated with vertebral
instability and epidural surgical scar increases
as the resected area expands (Payer et al., 2006).
When a thoracic approach alone is employed, resection of a spinal tumor may be difficult in somepatients (Payer et al., 2006). Therefore, combined

Fig. 2. Chest MRI shows a tumor invading the spinal canal (arrow) via the intervertebral foramen (Eden type IIIdumbbell tumor).

Fig. 3. CT myelography reveals that the thoracic spinal
cord is markedly compressed by the tumor (arrow).

92

Neurogenic dumbbell tumor

Fig. 4. Thoracoscopic findings shows a large intrathoracic tumor communicating with the 11th intercostal nerve.

Fig. 5. The resected tumor measures 78 × 48 mm. The
part of the tumor in the spinal canal is remarkably burned
by electrocautery for marking (arrow).

posterior and thoracic approaches are suggested
for Eden II and III types (Nakamura et al., 2000).
When the tumor size is large, as in this patient, excision by a posterior approach alone is difficult, anda thoracic approach may also be necessary.
In comparing thoracotomy with thoracoscopic
surgery for intrathoracic neurogenic tumors, thoracoscopic surgery was superior in the incidence of
postoperative complications such as pain, durationof hospital stay after surgery and operation time(Cardillo et al., 2008); however, they switched thoracoscopic surgery to thoracotomy in 13 of their 57
patients, and emphasized the need to pay attention
to the apical region and costophrenic angle when
the tumor size was larger than 6 cm (Cardillo etal., 2008). Thoracoscopic surgery is also useful forneurogenic dumbbell tumors, and recent advancements in the thoracoscopic surgical technique facilitated expansion of its indication, even for large
sized tumors. This tumor was large, about 8 cm

ABFig. 6. In the pathological findings, 2 different patterns are recognized, designated by Antoni as A and B. The type A
areas are composed of spindle cells arranged in a palisading fashion (A). In type B areas, isolated tumor cells with bizarre hyperchromatic nuclei are observed (B). Mitoses are extremely scanty in both patterns with hematoxylin and eosin
staining under a high-power field. Bar = 50 µm.

93M. Wakahara et al.

in diameter, but resection could be completed bythoracoscopic surgery. Considering thoracoscopic
surgery based on Eden’s classification, types II,
III and IV are appropriate indications, but type I
is not (Nakamura et al., 2000; Grillo et al., 2003).
Type IV may be resectable by thoracoscopic surgery alone, but treatment of the region advancing
into the intervertebral foramen requires consultation with apinal surgeons. Regarding the surgical procedure, an intraspinal procedure should beperformed to avoid spinal cord damage, followedby complete thoracoscopic resection of the residualtumor so as to open the intervertebral foramen.
The dura mater is resected in type II cases because
it is invaded, for which attention should be paid in
the occurrence of cerebrospinal fluid leakage as a
postoperative complication.
For treatment of posterior mediastinal neurogenic tumor, the presence of the dumbbell typeshould be always considered, and when surgery isselected, the procedure should be based on Eden’sclassification. Thoracoscopic surgery may be applicable even for large tumors.

References
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Received March 18, 2009; accepted March 30, 2009
Corresponding author: Hiroshige Nakamura, MD94