A wide variety of benign and malignant tumours can occur in the parapharyngeal space. The management of a patient with such a tumour, represents a challenge for the Head and Neck Surgeon.
HPC is a neoplasm of uncertain cell type origin. It is an uncommon spindle cell tumour, constituting 2.5% of soft tissue neoplasms and occurs primarily in adult life (median age 45 yrs, with peak prevalence in the sixth to seventh decade of life), appearing with an equal sex distribution 9-11
. It is frequently aggressive and has a tendency to recur and metastasize. Approximately one-third of all HPCs occur in the head and neck. Primary parapharyngeal space HPCs are very rare neoplasms and, according to the international literature, only a few cases have been reported, with some of them referring to tumours that invade the parapharyngeal space from other sites of the head and the neck 12
A painless mass is the most common presentation of head and neck HPCs. The clinical behaviour varies depending on the different grading of each case. The diagnosis cannot be made on the basis of clinical and gross morphologic characteristics. Definitive diagnosis of HPC is provided by the accurate histopathologic assessment, which determines the accurate management and prognosis 13
. The prediction of the clinical behaviour of HPC is not always clear and does not always correlate with the histolopathologic features of the tumour. Strict universal histopathologic criteria, for malignancy, have not been identified and vary between different studies. Generally, large size (> 5 cm), increased mitotic rate (> 4 mitosis/10 H PF), with the presence of atypical mitosis, high cellularity, pleomorphic tumour cells and foci of haemorrhage and necrosis predict a highly malignant course 8 13
The correct pre-operative imaging evaluation of HPCs is of great importance for scheduling the surgical plan. The tumour usually appears as a solid mass, hypodense on CT and isointense on T1-weighted images on MRI. On T2- weighted images, the tumour shows equal or lower signal intensity compared with the surrounding structures, although, in some cases, hyperintense signals have been described 14
. Due to better contrast resolution, MRI is superior compared to CT in demonstrating the morphological characteristics of these tumours, as well as their extension to the contiguous anatomical structures, especially at the base of the skull. In these highly vascularized tumours, vessels could also be seen as signal voids, on MRI, but not on CT. Although MRI is essential for accurate surgical planning and should be referred as the "gold standard", the imaging characteristics of the HPCs may be non-specific, demanding a differential diagnosis from other types of vascular or non-vascular tumours, especially those with prominent vascularization, such as juvenile haemangioma, glomus tumour, angiosarcoma, leiomyoma, leiomyosarcoma, schwannoma, mesothelioma, liposarcoma, benign and malignant histiocytoma, synovial sarcoma, chondrosarcoma, neuroblastoma, adenoid cystic carcinoma and mixed cell tumour 15 16
Conventional angiography may be helpful for pre-operative differential diagnosis and is useful for the possibility of pre-operative embolization 5 17
, which has been suggested as an option for decreasing tumour vascularity and size. Moreover, some Authors use routine angiography and peri-operative embolization in order to reduce intra-operative haemorrhage 18
. In our patient, there was no need for such a procedure due to the small size of the tumour.
Although histopathology of HPCs has been well documented, fine-needle aspiration biopsy (FNAB) findings have rarely been described in the literature 19-21
. A primary diagnosis of HPC is difficult to make with the use of FNAB. Cytologic analysis may allow the diagnosis of a recurrent or metastatic HPC 20
In our Department, we do not advise incisional biopsy for tumours with considerable vascularity, due to the fear of bleeding and consequent fibrosis. Furthermore, we do not use FNAB because, these tumours will eventually be treated surgically, regardless of the pre-operative cytologic findings. FNAB may be particularly helpful in cases in which the suspicion of harbouring a malignancy is high.
The treatment of choice is radical excision of the HPC with a sufficient cuff of healthy tissue. Unfortunately, this is not always possible for para-pharyneal space tumours, making the need of adequate exposure mandatory, which is accomplished by stylo-mandibular tenotomy.
Adjuvant radiotherapy and chemotherapy may be employed, although the literature is not quite clear about their results. HPCs are considered to be relatively resistant to radiotherapy. Radiotherapy is reserved only as adjuvant therapy in cases of incompletely excised lesions, recurrent tumours, and tumours with high-grade histopathologic features. Although chemotherapy may have a role in the treatment of distant metastatic disease, its role in the primary treatment remains to be clearly defined. Vincristine, Adriamycin, and Cyclophosphamide have all been used with variable success in cases of aggressive HPCs (8Y10). Some additional reports show that the use of interferon may be of benefit in patients with pulmonary HPC metastases 22
HPC appears to present a survival rate that may vary from an overall 10-year rate of 70% 8
to a considerably reduced 10-year survival rate in cases of > 4 mitosis/10 H PF (9%) or necrosis (29%) or tumour size > 6.5 cm (63%) 9
. Some studies report local recurrence rates as high as 40%, with metastatic disease in 15% of the cases 23
reported to have a latency period which varies from 63 to 107 months 24
No clear consensus, regarding the follow-up planning, seems to exist. In our case, we propose clinical evaluation every 6 months and an annual imaging study for at least 3 years. In our case, the patient performed a CT scan 1 year after the operation with no evidence of recurrence or residual disease