|Year : 2008 | Volume
| Issue : 3 | Page : 23-25
Myoepithelial carcinoma in infratemporal fossa
Sayan Kundu, S Chatterjee, D Mondol, AG Dastidar, A Roy
Department of Radiotherapy, Medical College Hospital, Kolkata-700073, India
|Date of Web Publication||30-May-2009|
Department of Radiotherapy, Medical College Hospital, Kolkata-700073
Source of Support: None, Conflict of Interest: None
A 20 year old female presented with swelling of right cheek and complete loss of vision in her right eye for 6 months. Lower motor neuron (LMN) palsy of facial (VII) nerve was evident. CECT scan suggested an illdefined non-enhancing mass lesion in right infratemporal fossa. The mass was excised. Histopathology confirmed diagnosis of myoepithelial carcinoma. Following surgery, patient received adjuvant chemotherapy and radiotherapy. Myoepithelial carcinoma of soft tissue is rare, and has been recognised recently. The case is being reported on account of its rarity.
|How to cite this article:|
Kundu S, Chatterjee S, Mondol D, Dastidar A G, Roy A. Myoepithelial carcinoma in infratemporal fossa. Indian J Med Paediatr Oncol 2008;29:23-5
|How to cite this URL:|
Kundu S, Chatterjee S, Mondol D, Dastidar A G, Roy A. Myoepithelial carcinoma in infratemporal fossa. Indian J Med Paediatr Oncol [serial online] 2008 [cited 2020 Oct 22];29:23-5. Available from: https://www.ijmpo.org/text.asp?2008/29/3/23/51419
| Introduction|| |
Myoepithelial Carcinoma, a rare tumour primarily occurs in the parotid and other major and minor salivary glands.
| Case|| |
A 20 year old female presented in November 2006 with a swelling in right cheek with decreased sensation over right face for about 6 months and complete loss of vision in her right eye. The swelling had gradually increased in size over past few weeks. She also complained of 2-3 bouts of severe epistaxis from right nose. The patient did not have trismus. Examination revealed a diffuse mass over right face which was palpable. Mass was not extending into the oral cavity or oropharynx. There was no cervical lymphadenopathy. Ophthalmological findings revealed no perception of light and nonreacting pupil of right eye and papilloedema and pale disc on direct ophthalmoscopy. Examination of left eye was normal. Lower motor neuron (LMN) palsy of facial nerve (VII) and sensory abnormality of first and second divisions of trigeminal nerve (V1 & V2 ) of right side were evident. Other cranial nerves were found to be normal. Complete ENT examination and hematological parameters were within normal limits. CECT scan suggested an illdefined non-enhancing mass of 46Χ37Χ55 mm in right infratemporal fossa with an anterior bowing of posterior wall of right maxillary antrum [Figure 1]. The mass was extending into the posterior part of nasal cavity through the enlarged pterygo-maxillary fissure and into the orbital apex through the inferior orbital fissure.
Patient underwent surgery - Mass was excised by extended rhitidectomy by Fisch's infratemporal fossa approach. There was gross residual disease after the excision. Histological revealed the tumour composed of spindle shaped cells with nests, cords and trabeculae of epitheloid cells[Figure 2]&[Figure 3]. The tumour was well vascularised and epitheloid cells exhibited mitotic figures. The tumour cells were immunoreactive for cytokeratin, smooth muscle actin, S-100 protein and vimentin. A diagnosis of myoepithelial carcinoma was made.
Post operatively, patient received 6 cycles of chemotherapy with Ifosfamide 2gm/m2/day iv D1-D3 along with mesna and Doxorubicin 20mg/ m2/day iv D1-D3 at 3 weekly intervals. Chemotherapy was followed by external beam radiotherapy after a gap of 4 weeks with telecobalt machine (Theratron 780C) to a total dose of 59.4 Gy/ 33#/ 6.5 weeks @ 1.8 Gy/ #. The patient was treated with antero-lateral beam arrangement with 30° wedge. Ipsilateral (right) eye could not be saved as the tumour had infiltrated the optic nerve. Special attention was given to save the contralateral (left) eye. The patient tolerated both the treatment modalities satisfactorily. The patient is currently on regular follow up and is asymptomatic.
| Discussion|| |
Myoepithelial carcinomas have been underrecognized in the past, as these were lumped under a broader category of "malignant mixed tumours" but the term has now been separated and added to second edition of the WHO histological classification of salivary gland tumours. Other synonyms includeepithelial- myoepithelial carcinoma, and clear cell carcinoma of salivary gland origin. 
The cell of origin of myoepithelial carcinomas are neoplastically transformed myoepithelial cells.  More than two-thirds of the cases arise in the parotid glands with no sex predilection. It can also originate elsewhere in other major or minor salivary glands or other organs e.g. breast.  Malignant myoepithelioma of soft tissue is extremely rare.  Myoepitheliomas and mixed tumours were only recently recognised to occur primarily in soft tissues, and only small case numbers have been described  . It is an intermediate to high-grade malignancy. Distant metastases to lung, liver and vertebrae are known but lymph node involvement is relatively rare. The clinicopathologic behaviour and outcome of the reported cases of myoepithelial carcinoma are variable and there are no discernible clinical features correlating unequivocally with behaviour. Di Palma and Guzzo considered myoepithelial carcinoma to be of low-grade when it arose in a pleomorphic adenoma and high-grade when it arose de novo. 
The tumour is usually encapsulated and may exhibit areas of necrosis and cystic degeneration. Four main histological variants are described, namely: spindle cell, plasmacytoid (hyaline), clear cell and epitheloid. Nuclear atypia ranges from mild to marked. Solid, fascicular, trabecular and lacelike growth patterns are common. There can be various amounts of myxoid, collagenous or hyaline stroma.  In our case, the tumour was composed of spindle-shaped cells with nests, cords and trabeculae of epitheloid cells which exhibit mitotic figures.
Tumour cells show variable immunoreactivity for cytokeratin (93%), S-100 protein (87%), calponin (86%), epithelial membrane antigen (63%), glial fibrillary acidic protein (46%), smooth-muscle actin (36%), p63 (23%) and desmin (14%). 
Myoepithelial carcinomas present as slow growing, painless mass and exhibit clinical findings similar to those of pleomorphic adenoma. On CT scan, this tumour appears as an enlarging mass with an indistinct margin and destruction of surrounding bone is seen. On MRI scan, it exhibits non-specific low T1 and T2- signal intensities.  CT scan in our case reveals non-enhancing SOL in the right infratemporal fossa with extension of the mass in posterior nasal cavity through enlarged pterygo-maxillary fissure and orbital apex through inferior orbital fissure.
Erdogan et al have recently described a malignant myoepithelioma arising in intracranial dura and it was the first convincing salivary gland type tumour to arise in an intracranial location outside the sellar region or ear  . As far as literature is concerned, this is the first convincing case of myoepithelial carcinoma arising in infratemporal fossa.
Due to non-availability of standard treatment guidelines, therapeutic approach to myoepithelial carcinoma is a dilemma. In past, surgery with or without pre or post-operative radiation has been used, akin to other salivary gland neoplasms.  As our patient had sarcomatous components in the tumour, we had added both chemotherapy and radiation as adjuvant therapy.
Thus, myoepithelial carcinoma is a rare tumour with clinicopathological diversity. Presently no definite management guidelines exist. Infratemporal fossa should be added to the list of tumour sites at which this morphologically heterogeneous tumour may arise.
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[Figure 1], [Figure 2], [Figure 3]