PLEOMORPHIC ADENOMA

Pleomorphic adenoma is also known as mixed parotid tumor or mixed salivary tumor.
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This is the most common tumor ofthe major salivary gland.
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Pleomorphic adenoma is benign epithelial tumor.
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Epithelial cells proliferate in strands or may be arranged
in form of acini or cords.
Pleomorphic adenoma is mixed tumor because of the presence
of epithelial cells, myoepithelial cells, mucoid material, pseudocartilage and lymphoid tissue.
Etiology
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Dardick’s theory: A neoplastically altered epithelial cell
with potential for multidirectional differentiation can be
responsible for pleomorphic adenoma.
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Differentiation of the ductal reserve cells: Intercalated
ductal reserve cells may be differentiated into ductal and
myoepithelial cells and later on these cells undergo Mesenchymal metaplasia as they inherently consist of smooth
muscle like properties.

Clinical Features :
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It occurs in middle aged women around 40 years are commonly affected.
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It is usually unilateral, present as single painless, smooth, firm, lobulated mobile swelling in front of parotid with positive Curtain sign, i.e. as the deep fascia is attached above to zygomatic bone, it acts as curtain, not allowing parotid swelling to move above the level of zygomatic bone. This is curtain sign.
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Obliteration
of
retromandibular
groove is common.
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Ear lobule is
raised
or lifted.
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Swelling is rubbery or firm. Soft area indicates necrosis. In
long standing cases it can be hard, surface can be nodular.
Skin is stretched and becomes shiny.
♦ When deep lobe is involved, swelling is located in lateral
wall of pharynx, posterior pillar and over soft palate. Deep
lobe tumor passes through Patey’s submandibular tunnel
pushing tonsils, pharynx, soft palate often without any
visible swelling or only small swelling when only deep
lobe tumor is present.
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Being a benign tumor it is neither adherent to the skin
nor to masseter.
♦ After few years pleomorphic adenoma shows features of
transformation into malignancy.

Investigations :
♦ Fine needle aspiration cytology:
It is done to confirm diagnosis
and
rule out the malignancy.
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CT scan: This is to be done when tumor arises from deep
lobe. It defines the extraglandular spread and extent of
parapharyngeal disease as well as cervical lymph nodes.
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FNAC of lymph nodes: Palpable lymph nodes in neck are to
be examined for malignancy.
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X-ray of bones: For seeing the bony resorption.
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MRI is the better method compared to CT scan. MRI provides better soft tissue delineation, i.e. superior perineural
invasion.

Complications:
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Recurrence in 5 to 50% of cases.
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Malignancy is seen in 3 to 5% of tumors
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Malignancy is seen in 10% of tumors in long duration.

Treatment :
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Surgery is the first line treatment.
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If only superficial lobe is involved, then superficial parotidectomy is done wherein parotid superficial to facial
nerve is removed.
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Various steps in superficial parotidectomy:
• Give incision, incision should start in front of tragus,
vertically descend downwards, curve round the ear
lobule till mastoid process and is carried till the neck.
• Facial nerve should be recognized which lies 1cm
inferomedial to pointed end of tragal cartilage of
external ear. Trace posterior belly of digatric till
mastoid process. Facial nerve lies between muscle
and tympanic plate.
• Both facial nerve and retromandibular vein divides the
parotid gland into deep and superficial lobes. Benign
tumors do not invade faciovenous plane of Patey.
• Gentle handling, good suction and nice hemostasis
provide visibility to nerve.
• Tumor along with lobe should be removed In Toto to
avoid spillage.
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If both the lobes are involved then total conservative parotidectomy is done. In this, tumor along with the normal
lobe is removed by retaining facial nerve. Avoid rupture
of gland