Recurrent Pleomorphic Adenoma

This chapter discusses the etiology, clinical presentation, assessment, and treatment of recurrent pleomorphic adenoma. Recurrent tumor following surgery (or any other treatment) usually presents as a recurrent swelling at the primary site, with or without local symptoms. The incidence of recurrence following surgery varies depending on surgical technique, surgeon's experience, duration of follow-up, and clinical integrity. A recurrence rate of less than 1% is generally considered acceptable. The best policy to prevent recurrence of pleopmorphic adenoma is excisional biopsy of the tumor with maximal safe margin and functional neurological preservation. Treatment is determined by the age and physical health of the patient, number of pervious operations, and anatomical extent of the recurrence. Treatment options include observation, local excision, superficial parotidectomy, total conservative parotidectomy, total parotidectomy with resection of the involved nerve and immediate nerve graft (any procedure is followed by radiotherapy), and radiotherapy alone.

Surgical Anatomy of the Parotid Gland

The parotid gland consists of two lobes: superficial and deep with regard to its relation with the facial nerve. It is wrapped around the mandibular ramus and secretes saliva through the parotid (Stensen's) duct. It is a paired organ, weighing 15-30g each. Its superficial lobe overlies the lateral surface of the masseter muscle and is bounded superiorly by the zygomatic arch, while its deep lobe is located in the pre-styloid compartment of the parapharyngeal space between the mastoid process posteriorly, ramus of mandible anteriorly, and external auditory meatus superiorly. Medially, the gland reaches to the styloid process. Inferiorly, the parotid tail extends down to the anteromedial margin of sternocleido-mastoid muscle. Several structures run through the parotid gland, namely, terminal segment of external carotid artery, retro-mandibular vein, parotid lymph nodes, and facial nerve, which soon gives two divisions (temporo-facial and cervico-facial) that give off five branches inside the gland radiating forwards. This chapter explores the surgical anatomy of the parotid gland.

Extra-Temporal Facial Nerve Reconstruction

Hypoglossal-facial anastomosis (HFA) as an end-to-end anastomosis (EEA) has several advantages, and indirect HFA with interposition graft is a safe and excellent method. The extended HFA is the method of choice for all malignant tumors that require extensive resection of the facial plexus, especially when combined with a neck dissection. Facio-facial anastomosis combined with HFA leads to excellent results when resection defect is restricted to the central portion of the facial plexus. Good functional rehabilitation of the musculature of the oral sphincter system is achieved using the hypoglossal nerve. To innervate the musculature of the ocular sphincter system, a facio-facial anastomosis between the nerve trunk and the cranial nerve branches is made using a free nerve transplant. Dynamic reanimation involves nerve repair, nerve transfer, regional muscle transfer, or free-muscle transfer. Dynamic reconstructive techniques can yield improved facial symmetry, spontaneous and symmetrical smile, eye closure and protection, and oral competence.

Parotid Gland Lymphoma

Lymphoma accounts for 15% of malignant salivary gland tumors. The parotid gland is the most commonly affected salivary gland (80%). It is generally seen in older men and women. It is associated with human immunodeficiency virus (HIV) infection and in approximately 6% of patients with Sjogrin's syndrome. There are two types: Hodgkin lymphoma and Non-Hodgkin lymphoma. Parotid lymphoma may be primary or secondary (far more common). Primary lymphoma first involves the parotid gland and later other parts of the body including lymph nodes and bone marrow. Secondary lymphoma involves other parts of the body first, such as peripheral blood, lymph nodes, bone marrow, and other organs. Treatment depends upon stage, overall health, age, and subtype of lymphoma. It includes chemotherapy, total or radical parotidectomy, and radiotherapy. If there is no response, or the chance of recurrence is high, then bone marrow transplantation or stem cell transplantation can be considered.

Malignant Epithelial Tumors of the Parotid Gland

Cancer of the parotid gland represents about 20% of all parotid tumors. It either occurs “de-novo” or “on top of pleomorphic adenoma.” There is no sex predilection, and the age of developing this cancer is usually above 50 years. Malignant tumors are as varied as their benign counterparts. Certain tumors are “low-grade” (polymorphous low-grade adenocarcinoma, acinic cell carcinoma, epithelial-myoepithelial carcinoma), while others are “high-grade” (salivary duct carcinoma, large cell carcinoma, and small cell carcinoma). The first echelon lymph node (LN) of metastases is the intra- and peri-glandular nodes. The next echelon is level II LNs. Hematogenous spread occurs very late and is mainly to the lungs and bones. However, adenoid cystic carcinoma tends to grow through peri-neural lymphatics with increased risk of nerve involvement, intra-cranial extension, and increased rate of recurrence. In this chapter, characteristic features and management of the individual types of malignant parotid tumors will be discussed.

Parotid Injuries and Fistulae

Successful treatment of parotid injuries depends on early recognition and appropriate early intervention. Sequelae of inadequate diagnosis and treatment include parotid fistula and sialocele formation, which are inconvenient for the patient and more difficult to treat than the initial injury. A parotid fistula is a communication between the parotid gland (glandular fistula) or duct (ductal fistula) and the skin externally (external fistula) or to the oral cavity internally (internal fistula). A sialocele is a collection of saliva beneath the skin that occurs if the duct leaks but no fistula forms, or when the glandular substance, but not the duct, is disrupted. Management options include pressure dressings and use of anti-sialagogues, total parotidectomy, tympanic neurectomy, intra-oral transposition of the parotid duct, radiation therapy, the use of botulinum toxin A, and the use of fibrin glue.

Evaluation of the Parotid Gland

This chapter describes the clinical, laboratory, imaging, endoscopic, and histological methods for evaluation of the parotid gland. Diagnostic approaches of parotid gland disorders include clinical evaluation in the form of history-taking (complaints, demographic data, medical profile, medications, and history of the parotid mass itself) and physical examination (intra-oral, extra-oral, and bidigital examination). Laboratory tests entail saliva collection for detection of changes in salivary flow and/or composition. Parotid gland imaging include plain x-ray, sialography, ultrasound (US), computed tomography (CT) scan and CT-sialography, magnetic resonance imaging (MRI), and MR-sialography. Other studies include endoscopy (sialoendoscopy) and parotid biopsy (core-biopsy, frozen-section) and fine needle aspiration cytology (FNAC).

Parotidectomy

In this chapter, the history of parotidectomy is provided, and indications, contraindications, pre-operative planning, and the different techniques of parotidectomy procedures are described. These include different types of parotidectomy (superficial or lateral parotidectomy, radical parotidectomy, and extended total parotidectomy), limited procedures (partial superficial parotidectomy and extra-capsular dissection), and enucleation (extra-capsular and intracapsular). Indications include neoplasms, inflammatory lesions, salivary duct stones, and sialorrhea. Post-operative complications are discussed. These are either early complications (facial nerve palsy, bleeding/hematoma, surgical site infection, skin flap necrosis, salivary fistula/sialocele, seroma, external otitis, and trismus) or late complications (Frey's syndrome, hypertrophic scar/keloid, unsightly scar, soft tissue defect, and recurrence).

Sialadenitis and Sialadenosis

In this chapter, the etiology and management of salivary gland inflammation (sialadenitis) and sialadenosis (sioalosis) are discussed. Causes of inflammatory disorders of the parotid gland include viral infections; bacterial infections; recurrent parotitis of childhood; papillary obstructive parotitis; granulomatous sialadenitis; autoimmune sialadenitis including Mickulicz disease, Sjogren's syndrome; and other autoimmune sialadenitis such as Wegener's granulomatosis, Kimura's disease, and chronic sclerosing sialadenitis. Sialadenosis is a chronic, diffuse, non-inflammatory, non-neoplastic disorder causing diffuse enlargement of salivary glands, usually the parotid glands. Grossly, there is only diffuse enlargement of the affected gland, and histologically, the condition is characterized by acinar hypertrophy and fatty infiltration. Patients present with painless, soft, and diffuse enlargement of both parotid glands. Treatment in the form of controlling the underlying disorder or withdrawing the incriminated drug helps sialosis to resolve.

Calculi of the Parotid Gland

Sialolithiasis is the most common disorder of major salivary glands with approximately 80% to 95% occurring in the submandibular gland and 5% to 20% in the parotid gland. Parotid stones are composed of organic substances such as cellular debris, muco-polysaccharides and glycoproteins, and inorganic substances, mainly phosphates and calcium carbonates. Conventional x-ray sialography combined with US is the method of choice for visualization of salivary gland calculi. Sialography and US are also inevitable in patient's qualification for diagnostic and therapeutic sialoendoscopy, thus avoiding sialadenectomy. An alternative, non-invasive diagnostic method is magnetic resonance imaging (MRI), MR sialography (MRS), or unenhanced computed tomography (CT). Therapeutic options include parotidectomy, external lithtripsy, and interventional sialoendoscopy.