Parapharyngeal space tumours are not very frequent, accounting for some 0.5% of neoplasms of head and neck. Most of these tumours (70%-80%) are benign and 40-50% of these originate in the salivary glands, particularly the pleomorphic adenoma 1. Pleomorphic adenoma in the parapharyngeal space (PPS) can develop de novo or may arise from deep lobe of the parotid and extend through the stylomandibular tunnel into the PPS 2. The origin of de novo pleomorphic adenoma is probably from displaced or aberrant salivary gland tissue within a lymph node 3. However, pleomorphic adenoma arising de novo in the parapharyngeal space is extremely rare which made us to report these cases.

Tumours arising in the minor salivary glands account for 22% of all salivary gland neoplasms 4. Majority of them are malignant with only 18% being benign. Of all the benign tumours pleomorphic adenoma is the commonest 4. The most common site of pleomorphic adenoma of the minor salivary glands is the palate followed by lip, buccal mucosa, floor of mouth, tongue, tonsil, pharynx, retro molar area and nasal cavity 4567. Pleomorphic adenoma of the parapharyngeal space is rare. De novo occurrence of the pleomorphic adenoma in our patients can arise from displaced or aberrant salivary gland tissue within a lymph node in the parapharyngeal space as suggested by Varghese et al 3.

Another source of such tumour is deep lobe of parotid gland, in which case the tumour may present as a dumb bell tumour abutting the stylohoid ligament 8. A comprehensive review of literature showed very few case reports of pleomorphic adenoma arising de novo in the parapharyngeal space 3.

Though most of the benign tumours of the minor salivary gland in the oral cavity present as a painless submucosal swelling 4, those from the parapharyngeal space may show additional symptoms, like otalgia, neuralgia, palsies of 9^th, 10^th, or 11^th cranial nerves or trismus. Classical findings of benign parapharyngeal swelling are a submucosal swelling in the lateral pharyngeal wall with or without extension to retromandibular fossa or the submandibular trigone and bimanual ballot ability 8910.

CT scan and MRI are important diagnostic tools in tumours of parapharyngeal space. These help in determining the extent of disease, local spread and also help to some extent in determining the type of tumour. Contrast enhancement is seen in vascular and neurogenic tumours. Presence of intact fat plane helps in distinguishing benign tumours from malignant ones. Extension of tumours from the deep lobe of a parotid gland is distinguishable from tumour arising de novo in parapharyngeal space by a fine translucent line representing the compressed layer of fibroadipose tissue between the tumour and deep lobe of parotid 11. MRI has been shown to be superior to computed tomography in the investigation of parapharyngeal space tumours 121314.

Fine needle aspiration cytology is the modality of choice for obtaining biopsy sample for diagnosis 2. Incision biopsy is no more advocated for salivary gland tumour due to seeding of tumour and subsequent multinodular recurrence 215.

Histopathologically, pleomorphic adenoma is an epithelial tumour of complex morphology, possessing epithelial and myoepithelial elements arranged in a variety of patters and embedded in a mucopolysaccharide stroma. Formation of the capsule is a result of fibrosis of surrounding salivary parenchyma, which is compressed by the tumour and is referred to as "false capsule" 11.

The treatment of pleomorphic adenoma is essentially surgical 23816. Though these tumours are apparently well encapsulated, resection of the tumour with an adequate margin of grossly normal surrounding tissue is necessary to prevent local recurrence as these tumours are known to have microscopic pseudopod like extension into the surrounding tissue due to "dehiscences" in the false capsule 11. The parapharyngeal space is however, a complex anatomic region located between the mandibular ramus and lateral pharynx and extending as an inverted pyramid from the skull base superiorly to hyoid bone inferiorly. Within this potential space are cranial nerves IX, X, XI, and XII, the sympathetic chain, carotid artery, the jugular vein and lymph nodes. Due to the PPS's anatomic complexity, location and surrounding vital structures, resection of tumours from this space can prove challenging to the head and neck surgeon. The approach of choice to the parapharyngeal space to allow adequate removal of the tumour should meet two criteria: wide intra-operative visibility for safe radical dissection and minimal functional and or cosmetic after-effects.

Traditionally, PPS surgery mainly uses the transcervical and parotid approaches. Malone et al. and Hamza et al. 1718 describe the resection of PPS tumours using the transcervical approach alone in 90-100% cases. Hughes et al. 8 published a series of 172 cases using the transcervical and trans-parotid approaches in 94%, using mandibular osteotomy in only 2% of resections. The tran-soral approach described by Ehrlich 19 in 1950 is indicated for small, non vascular tumours, as it offers poor exposition and does not give adequate control in the event of haemorrhage. Works published by McElroth et al. 20 in 1963 describe the use of this approach along with ligature of external carotid artery to remove PPS tumours in a study on 112 patients. More recently, in 1989 Goodwin and Chandler 21 considered this approach to give adequate access to the PPS, as it gives direct access to the PPS. It is very useful combined with other techniques, as it allows the deepest part of the tumour to be exposed, allowing for the removal of larger tumours. The several kinds of mandibular osteotomies have been described in the literature to give excellent exposure. We prefer to use trans -oral approach in small tumours and a standard trans-cervical approach for large benign PPS tumours.

Pleomorphic adenoma arising de novo in the parapharyngeal space is of rare occurrence. High index of suspicion and an adequate clearance of the tumour with a cuff of surrounding dispensable normal tissues is the key to successful treatment of such tumours.

Written informed consent was obtained from both the patients for publication of this case report the copy of the consent is available with Editorial office.

The authors declare that they have no competing interests.

AH prepared the draft and literature search. BH helped in preperation of manuscript. SAP conceived the idea and edited the manuscript. RK was involved in preparation of manuscript.