Facial Palsy in Non-Palpable Parotid Tumour
Abstract:
Adenoid cystic carcinoma is a malignant tumour which usually involves the minor salivary glands.When the parotid gland is involved, patients present with facial weakness even before a mass is palpable. We present one such case.
Key Words:
Adenoid cystic carcinoma, cylindroma, perineural invasion, neutron radiotherapy.
Case:
Mrs. V is a thirty two year old lady who presented to us with the complaint of deviation of angle of the mouth to the left for the past one year. It was first noticed following the delivery of her second child. Though some improvement was noticed initially, it gradually worsened.
On examination, Lower motor neuron (LMN) facial paralysis + (Rt)
Slight bulge of the right tonsil medially was noted on inspection of the oral cavity.
Keeping in mind the possibility of a parapharyngeal tumour /tumour arising from the deep lobe of the parotid, we obtained an MRI scan which clinched the diagnosis (Fig.1)
After pre-operative work up, she was taken up for surgery. A total parotidectomy with sacrifice of the facial nerve was done. (Fig.2).
The malignant cells infiltrating the nerve sheath as well as the salivary gland can be made out from figs. 3 & 4.
Her post operative period was uneventful and she was discharged on the seventh day.
Discussion:
Adenoid cystic carcinoma, previously known as cylindroma is the most common malignant tumour of the minor salivary glands.It is relatively rare in the parotid. The peak age of occurrence is the sixth decade and it has an equal sex incidence. It is also known to affect the ear, nose, palate, paranasal sinuses and the tracheobronchial tree.
Salient Features:
Perineural invasion is a characteristic feature – hence, patients usually present with nerve paralysis even before a mass is palpable.
It shows a predilection for pulmonary metastasis. It is known to invade medullary bone and spread over the periosteum for quite some distance before producing significant bone resorption. Lymphatic spread is rare. It is stubbornly recurrent.
Pathology:
Gross: Small, poorly encapsulated, grayish lesions.
Microscopy: Cells composed of dark compact nuclei with scanty cytoplasm disposed in tubular, solid and cribriform patterns. Intercellular spaces are filled with hyaline material which is thought to represent excess basement membrane.
Clinical Features:
Swelling which may be associated with pain e/o nerve paralysis. Occasionally, trismus, temporomandibular joint dysfunction,discoloured saliva, formication may be the presenting feature.
Investigations:
FNAC may be done to obtain a histological diagnosis.
MRI Scan is particularly useful in differentiating a neoplasm of the deep lobe of the parotid from a parapharyngeal tumour by demonstration of fat planes.It also helps to identify involvement of vital structures and assess operability. Staging is usually done according to AJCC recommendations (TNM) .
Treatment:
Superficial/total parotidectomy – depending on the lobe involved. Facial nerve is sacrificed if paralysis is present pre operatively,if the nerve is encased by the tumour or if preservation would mean leaving behind gross residual disease. Presence of pulmonary metastasis is not a contra indication to surgery. Facial nerve function may be preserved by direct resuturing, nerve grafting or by dynamic muscle transfer.
Post operative radiotherapy is usually necessary ; especially when there is extraglandular disease, perineural invasion, direct invasion of regional structures and high grade histology. Adverse effects include mucositis and xerostomia.
Post operative chemotherapy is indicated if there is evidence of visceral spread. A combination of cisplatin, adriamycin and cyclophosphamide is usually preferred.
Neutron radiotherapy is an improvement over conventional radiotherapy. Here, neutrons are generated by accelerating protons or deuterons and impacting them on a beryllium target. The indications are nearly similar but local control can be achieved in 56 % of patients compared to 17 % for the latter. The five year survival rate is nearly 60 % for those with these tumours.
References:
- Cuschieri, Moossa and Giles.- essential surgical practice 3rd edition. pp.593
- Cotran, Kumar and Robbins – pathologic basis of disease. 5th edition. pp.752
- Internet source: Dr. George Laramore, University of Washington Medical Center, http://www.acor.org/acc/accf.html
Dr.Vijay. R, P.G.Trainee – General Surgery, Room No. B-36, P.G. Annexe, Kozhikode Medical College, Kozhikode – 8.
D.P.Rajan (Associate Professor) Department of General Surgery, Kozhikode Medical College.
