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|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 6 | Page : 1359-1361
Thoracic intramedullary spinal metastasis from carcinoma ex pleomorphic adenoma of the submandibular gland
PY Waghmare, K Abhaya
Department of Neurosurgery, Kokilaben Dhirubhai Ambani Hospital, Mumbai, India
|Date of Web Publication||11-Nov-2016|
P Y Waghmare
Department of Neurosurgery, Kokilaben Dhirubhai Ambani Hospital, Mumbai
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Waghmare P Y, Abhaya K. Thoracic intramedullary spinal metastasis from carcinoma ex pleomorphic adenoma of the submandibular gland. Neurol India 2016;64:1359-61
A 57-year-old gentleman presented with complaints of weakness in the left lower limb since 2 days. There was no history of trauma, fever and loss of sensation. His right leg was normal. In the past, there was a history of long-standing left submandibular gland swelling, for which he underwent surgery 6 months ago. During this surgery, excision of the submandibular gland was performed. Histopathology (HPE) showed pleomorphic adenoma. On examination, his power was grade 3/5 on the left leg and 5/5 on the right leg. Spinal examination showed no deformity or tenderness. Local examination of the face showed no swelling and no sign of any cranial nerve palsy. Magnetic resonance imaging of the spine [Figure 1] showed a well-defined 10 × 5.7 × 6 mm lesion at the level of lower border of D10 vertebrae on the left side with altered intramedullary signal in the dorsal cord from D4 to D12 vertebrae. Whole-body positron emission tomography –computed tomography did not show any metabolically active lesion. His infective screening was normal.
|Figure 1: MRI thoracic spine (a) T1-weighted image with contrast showing a well-defined intramedullary lesion at thoracic 10 spinal cord. (b and c) Axial view showing an intramedullary lesion in T2- and T1-weighted images|
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The patient underwent complete excision of the thoracic intramedullary spinal metastasis (TISM). Histopathology report revealed a carcinoma consistent with metastasis from carcinoma ex pleomorphic adenoma (CaExPa) of the submandibular salivary gland [Figure 2].
|Figure 2: Histopathology slides (a) showing spinal lesions with hypercellularity with nuclear pleomorphism and mitotic figures showing (b) cytokeratin-positive slides and (c) EMA-positive slides|
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Salivary glands tumors are rare, and the most common benign salivary gland tumor is the pleomorphic adenoma, which comprises approximately 50% of all salivary gland tumors and 65% of parotid gland tumors. Pleomorphic adenoma shows malignant changes during its natural history and occurs in three forms, i.e. CaExPa, carcinosarcoma and metastasizing carcinoma; the latter two are exceedingly rare.
CaExPa is defined as a carcinoma arising from a primary (de novo) or recurrent benign pleomorphic adenoma arising in the epithelial component. It is a rare, aggressive and poorly understood malignancy, which is most frequently seen in the parotid gland (67%), followed by the submandibular gland (15%), with the sublingual gland involvement being only 1%. It spreads through direct extension through the lymphatic vessels, and, rarely, hematogenously. Distant metastases are seen mainly in the lungs, bone and liver. Although metastatic neoplasms of the spine in the extradural location are common, pure intramedullary spinal cord metastasis is a rare manifestation with an incidence of 0.1-0.4%.
Spread of CaExPa to the spine is very rare and till now only two cases have been reported. Both cases are illustrated in [Table 1].,
Various hypotheses explaining the route of metastasis into the spinal cord parenchyma are as follows:First, a hematogenous spread via the artery or vertebral venous plexus (Batson's venous plexus) is believed to account for most cases. Second, tumor cells originating from carcinomatous meningitis infiltrate into the Virchow-Robin spaces of the vessels, penetrate the pial membrane, and invade the spinal cord parenchyma. The third mechanism is direct invasion from contiguous structures.
The treatment modalities for spinal intramedullary metastasis include radiotherapy, surgery, and chemotherapy. However, none of them have resulted in an improved survival rate. In addition, in selected cases of intramedullary spinal metastasis, which are single and with the patients having progressive neurologically deficits, surgical management can be an effective salvage procedure.
In this report, we encountered a patient who was operated for a left submandibular swelling, which was histopathologically determined to be a pleomorphic adenoma. Six months later, this patient presented with weakness in the left lower limb because of a mass in the thoracic intramedullary spine. This lesion on excision showed that it was metastasis arising from the CaExPA of submandibular gland.
This case is rare because only two cases till now, as per our knowledge, have been published showing a CaExPa metastazing to the spine; one from the parotid gland and the other from the soft palate.,
Here, we present the second case of spinal metastasis from salivary gland and the first case of spinal metastasis from the submandibular gland (CaExPa) [Table 1].
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[Figure 1], [Figure 2]