Glomus Tumor of the Pterygopalatine Fossa: A Rare Case Report

Abstract

The pterygopalatine fossa (PPF) is a challenging space and pathological processes in this anatomical space are uncommon. This report presents a case of glomus tumor right PPF in a 65 years old female patient who underwent tumor removal by endoscopic transnasal-transmaxillary approach with preoperative selective embolization of the right internal maxillary artery.

Introduction

The pterygopalatine fossa (PPF) is a challenging space due to its important vital relations, like the skull base and the orbit, but also due to the vascular and nervous elements that pass through it. Pathological processes in this anatomical space are uncommon [1]. Pterygopalatine fossa usually involved secondarily by direct extension from adjacent structures. Glomus tumor of the PPF is extremely rare. Surgery of the PPF is difficult because the space is well bounded and hard to explore. But due to technological advances in endoscopic surgery, the lesions of PPF usually removed by endoscopic-assisted surgery. It provide better visualization, reduce surgical risk and less postoperative morbidity [2]. This report presents a case of glomus tumor right PPF in a 65 years old female patient who underwent endoscopic surgery for the tumor.

Case Report

A 65-years old female patient presented to ENT OPD with complaints of right sided progressive nasal obstruction and intermittent bleed for the past 6 months. Anterior rhinoscopy revealed grayish polypoidal mass in the right nasal cavity. It bled easily on manipulation, and hence intranasal biopsy was not performed. There was no history of associated co-morbid conditions i.e. hypertension, diabetes mellitus, chronic kidney disease etc. Her routine blood investigations were within normal limits.

A contrast enhanced computed tomography (CECT) scan of the nose and paranasal sinuses demonstrated a 3 × 2 cm sized heterogenous soft tissue density in the right pterygopalatine fossa (PPF) that was widening the adjacent bony structures extending laterally to masticator space through pterygomaxillary fissure (PMF) and medially to nasal cavity via sphenopalatine foramen. (Fig. 1) Computed tomography (CT) angiography revealed that the tumor received blood supply directly from the right internal maxillary artery. A selective embolization of the right internal maxillary artery was performed during the same procedure to reduce vascularity of tumor and hence less intraoperative bleeding and better visualization.

Fig. 1.

Computed tomography (CT) of the nose and paranasal sinuses showing heterogenoussoft tissue in right pterygopalatine fossa (PPF) causing its widening, laterally extending to masticator space through pterygomaxillary fissure (PMF) and medially to nasal cavity via sphenopalatine foramen (SPF)

Patient underwent tumor removal by endoscopic surgery, about 24 h after the embolization of right internal maxillary artery. The tumor was removed by the endoscopic transnasal-transmaxillary approach of the PPF. After performing the endoscopic medial maxillectomy, the posterior wall of maxillary sinus was removed carefully and PPF reached. The tumor was removed completely by endoscopic approach without any intra-operative complications. Tumor was sent for histopathological examination. Bleeding was minimal due to the preoperative embolization of tumor arterial supply, minor bleed managed with the help of bipolar cauterization. Conventional medicated nasal packing done, which was removed day after surgery. Postoperative period was uneventful.

The histolpathological examination showed branching capillary sized vessels lined by endothelial cells surrounded by collars of uniform glomus cells forming nests and trabeculae. These cells stained positively with immunohistochemical stains for vimentin, smooth muscle actin (SMA) and CD34. (Fig. 2) The diagnosis of glomus tumor was made on the basis of histopathological examination and immunohistochemical staining. The patient is under regular follow up with no recurrence of the tumor till date.

Fig. 2.

(a) Histopathological examination showing shows branching capillary sized vesselslined by endothelial cells surrounded by collars of uniform glomus cells forming nests andtrabeculae (hematoxylin and eosin, 200X), (b) CD34 IHC highlights branching capillaries (200X), (c) SMA IHC show membranous and cytoplasmic positivity in glomus cells (200X)

Discussion

The pterygopalatine fossa (PPF) is a difficult to approach anatomic area. It is situated behind the posterior wall of the maxillary sinus, bordered by the pterygoid plates posteriorly and the greater sphenoid wing and middle cranial fossa superiorly. It has connections with the infratemporal fossa laterally through the pterygomaxillary fissure, the posterior nasal cavity medially through the sphenopalatine foramen, the orbit superiorly through the inferior orbital fissure, and the palate inferiorly through the palatine foramina. Structures present within the PPF include the internal maxillary artery and its branches, the maxillary division of the trigeminal nerve (V₂), and the vidian nerve [3]. Pathologic processes in this space are rare, with the most common disease processes being juvenile nasopharyngeal angiofibroma (JNA), neurogenic tumors, a perineural extension of sinonasal malignancy, meningoencephaloceles etc.

Preoperative diagnosis of PPF tumors is difficult due to the location of this anatomical space. Even though most lesions of the head and neck are accessible for biopsy through simple procedures, this is extremely difficult if not impossible in the PPF [4]. Diagnostic investigation includes catecholamine excess evaluation, CT, and MRI. CT and MRI are helpful in determining the primary tumor and its extensions. Despite rarely being secretory, all head and neck paragangliomas (PGs) should have plasma or 24 h urinary metanephrine or catecholamine concentrations measured. If catecholamine excess is present, synchronous pheochromocytoma or other functional PGs must be assessed. Nuclear imaging may be required for secondary lesion investigation. Genetic mutations have been described in PGs patients, and those with early onset should be evaluated, when genetic testing is available [5, 6].

Accessing the PPF is difficult, which is traditionally approached via an open method, such as lateral rhinotomy, midfacial degloving, facial translocation, transantral maxillectomy, and the Fisch C and D procedures. Although these procedures provide good exposure of the PPF, they are often complicated by unacceptable facial scaring and deformity as well as dysfunction of the facial and infraorbital nerves [7]. Endonasal endoscopic approaches avoid external incisions, maxillofacial osteotomies, provide excellent illumination and image magnification of the surgical field, thus reducing the potential morbidity and shortening the recovery period. These characteristics are advantageous especially when dealing with areas that are difficult to approach, such as the pterygopalatine fossa [8].

Angiography and selective embolization are usually necessary in the preoperative stage for tumors considered highly vascular, like JNA. But these are also useful in other tumors, in order to reduce intra-operative blood loss and improve visualization. The procedure should occur 24–48 h prior to surgery, in order to minimize tumor revascularization [1, 9]. Glomus tumors are benign and can be cured by complete excision. Although extremely uncommon, an aggressive tumor or malignant changes could develop and local recurrence or distant metastasis may ensue. In our case, we used a transnasal-transmaxillary approach, with an endoscopic medial maxillectomy and reached the PPF through the posterior wall of the maxillary sinus. This approach offered good visualization of the tumor. Bleeding was minimal probably due to preoperative selective embolization of the right internal maxillary artery.

Radiotherapy (RT) is advised in patients with large and recurrent tumors, where the morbidity is high. Stereotactic radiosurgery and stereotactic radiotherapy are new additions in the treatment of PGs. Stereotactic RT implies fractionated RT that offers the advantages of the low dose per fraction associated with a conventional fractionation schedule, with the precise localization and limited treatment volume of stereotactic radiosurgery. RT may control the disease by slowing its progression, but complete cure is unlikely to be achieved. Chemotherapy efficacy has not been demonstrated and peptide receptor radionuclide therapy may be an option in the future for malignant and unresectable PGs [5, 10].

Glomus tumors at uncommon sites are often diagnosed late, causing patients to go undiagnosed or misdiagnosed for many years. Awareness of this diagnosis is important for the prevention of unnecessary delay in the treatment of asymptomatic patients. The PPF is a difficult anatomical space to access surgically, but using endoscopic techniques, there is reduced postoperative pain and edema, and fewer neurovascular complications, improving the postoperative course of the patient.