Acinic cell carcinoma

ACINIC CELL CARCINOMA

Acinic cell carcinoma is a malignant epithelial neoplasm with tumor cells demonstrating serous acinar differentiation characteristrised by zymogen secretory granules in the cytoplasm

General features

–          Second most common epithelial malignancy of salivary glands which can occur bilaterally

–          Common sites – parotid (80%), intraoral minor salivary glands (buccal mucosa, upperlip) (17%),  submandibular gland  (4%) and sublingual gland (1%).

–         Women are more frequently affected than men and can occur at any age with peak incidence in the 7th decade

Clinical features – slowly enlarging mass with vague intermittent pain

Gross findings –  well circumscribed tumor with size ranging from 1 to 3cms.

–          Cut section is lobular and tan to reddish with firm to soft in  consistency

Microscopic features –

– Tumor is characterized by Serous acinar cell differentiation . Neoplastic acinar cells are large cells with granular, lightly basophilic cytoplasm and uniform, round, eccentric nuclei.

– Architectural growth patterns are solid, microcystic, papillary – cystic and follicular

– Cellular features are as acinar, intercalated ductal, vacuolated, clear and nonspecific glandular.

– Serous acinar cell differentiation – Cytoplasmic zymogen –like secretory granules are the cytologic features

– The intercalated – duct like cells – They are cuboidal and have eosinophilic to amphophilic cytoplasm and deeply basophilic to vesicular nuclei that are usually central in location. These cells surround luminal space which varies from small duct to large cystic spaces

– Vacuolated cells – Clear cells in Acinic cell carcinoma do not contain glycogen and are probably due to fixation or tissue processing artifact and due to alteration in the cytoplasmic organelles, such as dilation in the cytoplasmic organelles, such as dilation of endoplasmic reticulum.

– Non-specific glandular cells – These cells are round to polygonal cells with amphophilic to eosinophilic cytoplasm and round basophilic to vesicular nuclei typically occurring in syncitial sheets with poorly demarcated cell borders. they lack cytoplasmic granules.

– Stroma varies from delicate fibrovascular tissue to extensively collagenous tissue which may contain dense lymphoid infiltrate, hemosiderin laden macrophages, and psammoma bodies.

Differential diagnosis

– Cystadenocarcinoma with papillary patterns

– Mucoepidermoid carcinoma

– Polymorphous low grade adenocarcinoma

– Tumor with clear cells are epithelial-myoepithelial carcinoma, metastatic RCC, clear cell oncocytoma, . these tumor cells have glycogen in cytoplasm where as ACC tumor cells does not have glycogen.

Treatment – complete surgical excision of the tumor is recommended. Radiation therapy after complete excision may improve survival