Oral Pathology Short case 9 - Lump on the buccal mucosa

 Answer : Pleomorphic adenoma

The most common salivary gland tumour

2-3.5 cases / 100,000

Occurs in all ages

Most common 3-6th decades

Female : Male = 2 : 1

Parotid >Palate>Submandibular 

Usually solitary but synchronous or metachronus lesions may occus

Major glands – encapsulated

Minor glands – non encapsulated 

Histopathology

Main diagnostic Duct like structures and + mucin casts 

Epithelial component	Stroma
Ductal epithelial cells – 2 layered inner squamous and outer cuboidal Duct like Strands Islands	Myxoid
	Mucoid
Myoepithelial cells- produce stroma Spindle Plasmacytoid Ovoid Epitheliod	Chondroid – similar to hyaline cartilage
	Osseous

Squamous metaplasia and keratin pearls may not be unusual

Mutation – PLAG1

Hyalinization and very dense collagenation – Very high chance of malignancy

Types of malignancy arising from PA

• Ca. Ex – pleomorphic adenoma (Adeno ca, duct ca, myoepithelial ca)

• Carcino sarcoma

• Metastasizing PA – Histologically bening, can transform into malignancy 

Cluses for high recurrence

• Myxoid stroma

• Spillage during surgery

Tumours are some times encapsulated 

Histopathological confusion – polymorphus low grade ca, tubular variant of adeno ca

Confirm diagnosis – PLAG targeted antibodies 

Recurrance 

• Punctured – 26.9 %

• Spillage- 80 %

Malignant transformation rate 6.2%

High risk for malignant transformation 

• Multiple recurrances 

• Deep parotid lobe location

• Male sex

• Older age

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