Acinic Cell Carcinoma: Malignant Tumours of Salivary Glands

Other names:
1. Acinar cell carcinoma

2. Serous cell adenoma

Definition:
Acinic cell carcinoma is a malignant epithelial neoplasm in which the neoplastic cells express  acinar differentiation.

Origin:
It arises from embryonically entrapped salivary gland tissue in lymph nodes in or near the parotid compartment.

Notes:
1. Have at least low grade malignant potential.
2. Term is defined by cytological differentiation towards serous acinar cells whose characteristic feature is cytoplasmic PAS positive zymogen type secretory granules.
3. It is 3rd most common malignant salivary gland neoplasm after mucoepidermoid carcinoma and adenocarcinoma.

Clinical features:
1. Age: Middle age (44 years), F:M = 3:2
2. Site: Parotid (80%), most common intraoral sites are lips and buccal mucosa
3. Resembles pleomorphic adenoma (Encapsulated and lobulated)
4. Tumour presents as:
  a. Slow growing, mobile or fixed mass
  b. Asymptomatic usually (Pain and tenderness in one 3rd cases)
  c. Facial muscle weakness may be seen
  d. Bilateral synchronous tumor

Histologic features:
1. Exhibit cells of varying degrees of differentiation:

Four growth patterns are: 
  a. Solid pattern
  b Papillary cystic
  c. Follicular
  d. Microcytic


2. Mostly serous acinar cells with uniform, dark, round, eccentric nuclei and a granular basophilic cytoplasm

3. Other cells are intercalated duct cells and vacuolated cells

4. Lymphoid component is commonly seen (Not found in other intraoral salivary gland tumors). It helps in diagnosis.