Файл: NMS Surgery_booksmedicos.org.pdf

Treatment is by surgical excision. Local recurrence is common.

Kaposi's sarcoma (see Chapter 26, II G 2 d) is a rare tumor that arises in the skin or mucous membranes and presents as a bluish -red macule.

Kaposi's sarcoma is a manifestation of acquired immunodeficiency syndrome (AIDS).

Treatment. Head and neck neoplasms in these patients tend to be multiple and have usually been treated with radiotherapy.

P.392

C

Esthesioneuroblastoma (olfactory neuroblastoma) is a rare neurogenic lesion that arises from the olfactory mucosa at the roof of the nose.

Presenting symptoms

It presents as a nasal mass, with the usual symptoms of epistaxis and obstruction.

Involvement of the cribriform plate is routine, and intracranial extension is common.

Diagnosis. Pathologic diagnosis can be difficult. The workup includes a CT scan and, occasionally, angiography.

Treatment and prognosis

Treatment is done with combined intracranial and intranasal resection and radiotherapy in selected cases.

Local recurrence rates are high (50%), but metastasis is uncommon (20%).

The 5-year survival rate is approximately 50%.

However, because most of the literature predates the current mode of therapy, recurrence and survival statistics should improve.

D Tumors of the bone and soft tissue

Osteogenic sarcoma

Characteristics. Osteogenic sarcoma is the most common malignant tumor of bone. It rarely occurs in the head and neck. The most common site in the head and neck is the jaw. Reports include only about 12 cases that were primary to the temporal bone.

Etiology. Previous bone disease and prior irradiation have been implicated as etiologic factors.

Treatment is by radical excision.

The efficacy of adjuvant radiation therapy is controversial.

The most recent literature suggests that chemotherapy should be reserved for metastatic disease, but this suggestion is also controversial.

Prognosis. The 5-year survival rate is very poor.

Ewing's sarcoma

Characteristics. Ewing's sarcoma occurs in the skull and facial bones in approximately 9% of patients. It is usually a painful, swollen lesion.

Treatment is with radiation and adjuvant chemotherapy.

Prognosis. The 5-year survival rate is about 50%.

Ameloblastoma is a locally invasive tumor that arises from the odontogenic apparatus.

Presenting symptoms. Ameloblastoma usually presents as a painless swelling and is much more common in the mandible than in the maxilla.

Treatment is by conservative local excision. Radiation can be used for the rare malignant case.

Rhabdomyosarcoma (see Chapter 26, II G 2 c) is primarily a disease that occurs in children.

Characteristics. Rhabdomyosarcoma can occur in the orbit, oral cavity, pharynx, face, neck, ear, paranasal sinuses, or salivary glands.

Treatment. It is treated with radiation and chemotherapy.

Prognosis. Except for tumors in the orbit, which have an 80% 2-year survival rate, the prognosis is poor.

Soft tissue sarcomas (fibro-, lipo -, and chondrosarcomas [see Chapter 26, II G ]) are quite rare in the head and neck.

Etiology. They are associated with prior irradiation.

Treatment is with surgery and radiation. Local recurrence rates are high.

Chordoma is a rare tumor that arises from the embryonic notochord.

Characteristics. One half of these tumors occur in the craniocervical region.

Presenting symptoms

They are slow -growing, locally invasive tumors that cause bone and soft tissue destruction. They can present as a nasopharyngeal mass.

Treatment is with surgical excision, radiation therapy, or both. Local recurrence rates are high.

Chapter 20

Parotid Gland

R. Anthony Carabasi III

John C. Kairys

I Introduction

A Anatomy

Embryology. The parotid gland is the largest of the salivary glands. The average gland weighs 25 g. It appears in the fourth week of gestation and originates from the epithelium of the oropharynx.

Description

The gland covers the masseter muscle, extends posteriorly beyond the vertical ramus of the mandible, and abuts the external auditory meatus.

The gland is enclosed by a dense fascial sheath. The tightness of this fascia is responsible for the severe pain that accompanies acute swelling of the gland (acute parotitis).

Classically, the parotid gland was thought to have two lobes, superficial and deep. Anatomically, this is probably not the case, but it is useful to think of the gland in this way when discussing the surgical treatment of parotid disease.

Drainage of saliva is via Stensen's duct. This duct exits anteriorly, pierces the buccinator muscle, and enters the oral cavity opposite the second upper molar. The opening is marked by the parotid papilla, which may be felt by the tongue or a finger.

B Innervation of the parotid gland

(Fig. 20 -1)

The facial nerve enters the posterior part of the gland immediately after emerging from the stylomastoid foramen. This nerve divides within the substance of the gland into two parts, the zygomaticofacial and the cervicofacial, which eventually split into five major branches:

Temporal

Zygomatic

Buccal

Mandibular

Cervical

The facial nerve and its branches separate the superficial and deep portions of the gland (Fig. 20 -2).

The muscles of expression are supplied by the facial nerve on the ipsilateral side of the face.

II Benign Neoplasms

Approximately 80% of parotid tumors are benign. The most common presenting feature of these tumors is a painless mass. Many are multicentric and have a high incidence of local recurrence. Facial paralysis is rare. Very careful identification and surgical treatment, which consist of excision that includes a margin of normal gland, are required. Extension into the deep lobe requires a total parotidectomy. The facial nerve should be spared, if

possible, during surgery for benign parotid neoplasms. A discussion of the different types of benign tumors follows.

A Mixed tumors

Mixed tumors are so named because they contain both stromal and epithelial components.

Mixed tumors are the most common benign salivary tumors and account for 60% of all parotid tumors. P.394

FIGURE 20-1 Innervation of the parotid gland.

They are slow -growing tumors but may be quite large at the time of presentation.

At surgery, mixed tumors often appear to “shell out” easily; that is, they seem easy to remove from the surrounding normal tissue. However, this excision invariably leaves nests of residual tumor, resulting in a recurrent tumor that requires re-excision.

Radiation therapy has no substantial effect.

B Papillary adenocystoma (cystadenoma) lymphomatosum (Warthin's tumor)

These tumors consist of both epithelial and lymphoid elements.

They are soft (cystic) when palpated.

This interesting tumor arises from the ducts of the gland. It is the most common parotid malignancy and constitutes 9% of all parotid tumors.

Types

Low-grade tumors are the more common form and are the tumors seen most frequently during childhood.

They generally feel soft when palpated and appear encapsulated at surgery.

They are treated by excision, with preservation of those facial nerve branches that are not directly involved by the lesion.

When low -grade tumors are treated properly, the 5-year survival rate is approximately 95%.

High-grade tumors are extremely aggressive, unencapsulated tumors that invade the gland widely.

Treatment must be radical and includes total parotidectomy, including the facial nerve, plus radical neck dissection (see Chapter 19, II D 1). Neck dissection is done even without palpable nodes, because there is a high incidence of microscopic nodal metastasis.

Surgery is usually supplemented by postoperative radiation.

The 5-year survival rate is 42% with optimal treatment.

B Malignant mixed tumors

These tumors are the second most common type of malignancy and are responsible for 8% of all parotid tumors.

The treatment is total parotidectomy; a radical neck dissection is also done for either palpable adenopathy or a high-grade tumor.

C Squamous cell carcinoma

Squamous cell carcinoma is a rare tumor in the parotid gland.

It is very hard on palpation and is usually accompanied by pain and nerve paralysis.

It is important to differentiate this lesion from a metastasis arising from a primary tumor elsewhere in the head and neck.

The 5-year survival rate is approximately 20%.

P.396

D Other lesions

Other lesions include adenocystic carcinoma (cylindroma), acinic cell adenocarcinoma , and adenocarcinoma.

Treatment is by total parotidectomy.

Neck dissection is added when obvious nodal disease for high-grade lesions is present.

High-grade, recurrent, and inoperable tumors should be treated with radiation.

E Malignant lymphoma

Malignant lymphoma may arise as a primary tumor in the gland. The treatment is the same as for other lymphomas (see Chapter 19, XI ).

IV Parotid Trauma

A Lacerations

Lacerations in the area of the parotid may damage the parenchyma of the gland, Stensen's duct, or the facial nerve.

Parenchymal damage without injury to Stensen's duct usually heals spontaneously.

Stensen's duct. If this duct is lacerated or transected, it should be repaired over a small catheter. This catheter is sutured to the oral mucosa and left in place for 10 days.

Facial nerve injuries

These nerves may recover spontaneously if only a distal branch is injured.

If a main trunk is injured, it requires meticulous repair by primary anastomosis or nerve grafting.

If the injured area is hard to expose, a superficial parotidectomy should be done to facilitate repair.

B Foreign bodies

Foreign bodies (e.g., bullets) should be removed.

V Inflammatory Disorders

A Acute suppurative parotitis

Acute suppurative parotitis is usually found in patients who are debilitated and dehydrated and who have poor oral hygiene.

The offending organism is usually Staphylococcus aureus.

It most likely enters the gland from the mouth via Stensen's duct.

The dehydrated patient whose salivary glands are not secreting actively is susceptible to rapid growth of the organism in this favorable environment.

The bacterial proliferation leads to an intense inflammatory reaction in the gland, with edema and severe pain.

Initial treatment includes hydration, antibiotics, and measures to promote salivation, such as occasionally sucking on a lemon.

Cultures are taken from Stensen's duct.

Antibiotics are initially directed against S. aureus and are later adjusted as indicated by the results of the cultures.

Surgical drainage is required if the process is not arrested by the preceding measures.

An incision is made around the angle of the mandible, and multiple horizontal incisions are made in the parotid fascia.

There are usually multiple abscesses, and each must be drained.

The wound is left open to ensure adequate drainage.

B Calculous sialadenitis

Calculous sialadenitis is a condition caused by stones in the salivary ducts. If obstruction of the duct occurs, inflammation and intermittent painful swelling of the gland follow.

Diagnosis

Radiographs may show the stones.

A sialogram, in which contrast dye is injected into the draining duct, also shows areas of obstruction and is useful in patients when the stone is not radiopaque.

Surgery

When the stone is near the end of the duct, it can be removed transorally.

P.397

If it is deep in the gland, it can be removed by an external incision.

If multiple stones are present and pain recurs, the entire gland should be removed.

Variants. Sialadenitis can occur without stones.

If there is a stricture of the duct on the sialogram, it should be dilated.

If symptoms persist, surgery may be necessary to remove the gland.

VI Evaluation and Management of Parotid Masses

A History and physical examination

History and physical examination can often differentiate among benign, malignant, and inflammatory processes.

A slowly enlarging, distinct mass can be either a benign neoplasm or a malignant neoplasm.

A rapidly enlarging, firm distinct mass associated with firm, ipsilateral adenopathy suggests a malignancy.

A mass associated with pain or facial nerve paralysis usually indicates a malignancy.

Acute, painful swelling in one or both glands, associated with fever or systemic symptoms, indicates an inflammatory process.

Intermittent pain and swelling in the gland suggest calculus sialadenitis. A stone may occasionally be palpable on intraoral examination.

A careful head and neck examination must be performed. Metastatic disease in a parotid lymph node (drainage from the upper two thirds of the face and the anterior scalp) may present as a mass in or near the parotid gland.

B Diagnostic studies

Diagnostic studies may provide information that dictates the extent of surgery required, thus permitting better counseling of the patient preoperatively. However, some surgeons argue that no diagnostic studies are required because operation is indicated in most cases, and the extent of resection is dictated by the pathology encountered.