Thoracic radiculopathy from a paravertebral mesothelial cyst

Acta Neurochir (Wien) (2006) 148: 989–991 DOI 10.1007/s00701-006-0815-4

Case Report: Craniospinal Cysts Thoracic radiculopathy from a paravertebral mesothelial cyst P. Perrini1 , N. Benedetto1 , A. M. Buccoliero2 , and N. Di Lorenzo1 1 2

Neurosurgical Department, University of Florence, Florence, Italy Department of Human Pathology and Oncology, University of Florence, Florence, Italy

Received December 15, 2005; accepted May 3, 2006; published online June 29, 2006 # Springer-Verlag 2006

Summary We report on an extremely rare case of a paravertebral thoracic mesothelial cyst in a young woman who presented with dorsal radiculopathy affecting the T5 dermatome. The patient underwent a standard transthoracic intercostal approach with removal of the cyst. During the operation, the T5 intercostal neurovascular bundle was found firmly attached to the lesion elucidating the origin of the radicular pain. To our knowledge, this is the first report of radiculopathy due to a paravertebral mesothelial cyst. Although highly unusual, paravertebral mesothelial cyst should be considered in the differential diagnosis for lesions inducing dorsal radicular pain.

she had experienced the onset of occasional midthoracic pain with a long period of quiescence. Two months before her admission, the pain worsened and assumed a burning-like character.

Keywords: Mesothelial cyst; radiculopathy; transthoracic approach.

Introduction Mesothelial or coelomic cysts of the mediastinum and pleura are congenital benign lesions usually asymptomatic and found incidentally by imaging studies. Although their typical location is in the anterior cardiophrenic angle (pleuropericardial cysts), their occurrence in unusual locations, such as in the paratracheal region, in the anterior mediastinum and in the paravertebral region has been described [3, 6, 7]. We report on an extremely rare case of a paravertebral thoracic mesothelial cyst presenting with midthoracic radicular pain. To our knowledge, this is the first described case of a dorsal radiculopathy caused by a paravertebral mesothelial cyst.

Case report A 27-year-old woman was referred to our department with a diagnosis of a paravertebral tumor at the T5 level. One year earlier,

Fig. 1. T2-weighted dorsal MRI scans. Coronal (A) and axial (B) images reveal a left paravertebral cystic lesion at the T5 level

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Fig. 2. Intraoperative photographs of the paravertebral mesothelial cyst resected via a left transthoracic approach. (A) After the thoracotomy, the lesion was identified beneath the parietal pleura near the thoracic aorta. (B) After the parietal pleura overlying the lesion was incised, the cyst was found firmly attached to the intercostal T5 neurovascular bundle (asterisk) elucidating the cause of the dorsal radiculopathy. (C) The 20  25 mm cystic lesion was removed en bloc after the neurovascular bundle was divided

At the initial clinical examination, the neurological status was normal. The patient described a persistent pain of the left hemithorax involving the T5 dermatome. Magnetic resonance (MR) imaging of the thoracic spine revealed a 20  25 mm cystic lesion in the left paravertebral T5 level without neural foramen involvement. As revealed by T2-weighted images the lesion was homogeneously fluid filled (Fig. 1A, B). No enhancement was observed after injection of the contrast medium. The patient underwent a standard left transthoracic intercostal approach in the right lateral position. The cystic lesion was easily identified beneath the parietal pleura, in the left paravertebral space, close to the thoracic aorta (Fig. 2A). The parietal pleura overlying the tumor was incised and the tumor dissection commenced. During the dissection, the T5 neurovascular intercostal bundle was found firmly attached to the cystic lesion and the bundle was divided close to the tumor before the lesion was removed en bloc (Fig. 2B). The lesion was a turgid ovoid cyst with a paper-thin translucent membrane, filled with water-like fluid (Fig. 2C). The parietal pleura was carefully closed, two temporary thoracic drains were positioned and the thoracotomy was closed in a usual fashion. The patient’s postoperative course was uneventful and her radiculopathy completely resolved. Follow-up MR images obtained 4 and 12 months after surgery revealed complete tumor removal. Histopathological examination revealed a cystic lesion composed of fibrous walls lined by a single layer of cuboidal mesothelial cells having

Fig. 3. Epithelial lining. The cyst is lined by a single layer of cuboidal uniform cells consistent with a benign mesothelial or coelomic cyst. Hematoxylin and eosin stain; original magnification, 200

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Thoracic radiculopathy from a paravertebral mesothelial cyst scanty cytoplasm and round-like hyper-chromatic nuclei consistent with a benign mesothelial or coelomic cyst (Fig. 3).

Discussion Mesothelial cysts are benign developmental anomalies and represent 5–10% of mediastinal tumors [6]. The advent of computed tomography (CT) scans and MRI have improved the diagnosis of these lesions and increased the detection of mesothelial cysts in unusual locations [5]. CT findings are straightforward and consist of a thin-walled lesion with near-water attenuation value. The absence of enhancement after contrast administration is required for radiological diagnosis of these lesions. MRI reveals signals similar to those of water on all imaging sequences and is mandatory to evaluate the mesothelial cysts located in the paravertebral area and to rule out tumors of meningeal or neurogenic origin [6]. Embryological reasons can explain the different possible locations of these cysts [6]. The pleural and pericardial cavity on one side and the peritoneal cavity on the other, arise from fusion of a series of disconnected mesenchymal lacunae. Failure of one of these coelomic lacunae to fuse or secondary migration of an isolated element can result in mesothelial cyst formation. An acquired origin of mesothelial cysts in unusual locations has been postulated. A proliferative reaction of normal mesothelial cells in response to different injuries such as trauma and infection has been hypothesized. Although more than 50% of mesothelial cysts are asymptomatic, they have been known to produce symptoms and signs due to compression of adjacent structures or due to complications such as infection [6], rupture [4] or hemorrhage [2]. Chest pain may occur in patients with intrathoracic mesothelial cysts usually as a consequence of torsion of the cyst [2]. Moreover chest pain has been reported in association with signs of cyst infec-

tion or herniation of the cyst at the level of the anterior chest wall [6]. To our knowledge the present case is the first report of dorsal radiculopathy caused by a paravertebral mesothelial cyst. Although highly unusual, paravertebral mesothelial cysts should be considered in the differential diagnosis for lesions inducing dorsal radiculopathy. The anatomical features of these lesions (rounded, fluid-filled and almost avascular) make them ideal for treatment by minimally invasive procedures such as endoscopic resection [6] or percutaneous ethanol sclerotherapy [1]. Surgical resection with conventional thoracotomy should be reserved for symptomatic lesions in which the diagnosis remains uncertain [6]. References 1. Akinci D, Akhan O, Ozmen M, Ozkan O, Karcaaltincaba M (2004) Diaphragmatic mesothelial Cysts in children: radiologic findings and percutaneous ethanol sclerotheraphy. Am J Roentgenol 185: 873–877 2. Borges AC, Gellert K, Dietel M, Baumann G, Witt C (1997) Acute right-sided heart failure due to hemorrhage into a pericardial cyst. Ann Thorac Surg 63: 845–847 3. Jamplis RW, Lillington GA, Mills W (1963) Pleural cysts simulating mediastinal tumors. J Am Med Assoc 185: 727–728 4. King JF, Crosby I, Pugh D, Reed W (1971) Rupture of pericardial cyst. Chest 60: 611–612 5. Manac’h D, Riquet M, Kao B, Souilamas R, Le Pimpec Barthes F, Briere J, Dujon A, Faillon JM (1999) Intrathoracic coelomic cysts. Rev Pneumol Clin 55: 13–19 6. Mouroux J, Venissac N, Leo F, Guillot F, Padovani B, Hofman P (2003) Usual and unusual locations of intrathoracic mesothelial cysts. Is endoscopic resection always possible? Eur J Cardiothor Surg 24: 684–688 7. Urschel JD, Horan TA (1994) Mediastinoscopic treatment of mediastinal cysts. Ann Thorac Surg 58: 1698–1700

Correspondence: Paolo Perrini, Neurosurgical Department, CTO, Largo P. Palagi 1, 50139 Firenze, Italy. e-mail: p.perrini@ neurochirurgiafirenze.it