Polymorphous Low-grade Adenocarcinoma Flashcards
Description
Uniform population of tumor cells that are arranged in a variety of architectural patterns (polymorphous).
It has previously been known as terminal duct carcinoma, lobular carcinoma, and low-grade papillary adenocarcinoma.
Site
- Occurs in minor salivary glands predominantly the palate in approximately 60% of cases
- May occur in major salivary gland in less than 5% of cases
It may also involve buccal mucosa, upper lip, base of tongue, and retromolar region. - Uncommon locations include major salivary glands, lacrimal gland, nasopharynx, and nasal cavity. PLGA may occur as a malignant component in carcinoma-ex-pleomorphic adenoma.
Prevelance
Second most common salivary gland carcinoma of palate and of oral cavity after Adenoid Cystic Carcinoma
Epidemiology
F:M = ~2:1
Mean age of diagnosis in the
50 - 60s
(range: 16 - 90)
Clinical presentation
- Slow growing painless mass
- Tumor may erode or infiltrate the bone
- Biologic behaviour is not low grade
- Perineural invasion is common r/o ACC
Investigations
Histology
Non-encapsulated lesion with infiltrative margins
It is named as polymorphous due to its different growth patterns:
* Tubular (glandular)
* Trabecular
* Microcystic
* Fascicular
* Cords
* Solid
* Cribriform
* Single filing
* Papillary
Architectural polymorphism is not unique to polymorphous low-grade adenocarcinoma and can be seen in many different salivary gland tumors.
Differential diagnosis:
1) Pleomorphic adenoma (PA)
2) Adenoid cystic carcinoma (ACC)
3) Secretory myoepithelial carcinoma
4) Secretory carcinoma
Treatment and Prognosis
Wide surgical excision with underlying bone
Prognosis is good
95%. The 5-yr survival rate is 95% with the low-grade type, primarily affecting mucus cells, and 50% with the high-grade type, primarily affecting epidermoid cells.
