Salivary Gland Carcinomas: Clinical and Pathological Features

Acinar Cell Carcinoma

Uncommon and usually asymptomatic. Lesions are typically small and often encapsulated.

Cellularity and Features

Similar to acinar cells, producing serous secretions (non-basal granular cells). There are acinar tubules, papillary masses, and solid areas with necrosis. Peripherally, there is a lymphoid infiltrate. It can produce metastases in lymph nodes, lungs, and bone.

Sample Findings

Displays dense material with high cellularity, no PMN, lymphocytes, red cells, histiocytes, or necrotic debris.

Mucoepidermoid Carcinoma

Found in the sideboards and periphery of the parotid gland, and also in minor glands. There can be areas of necrosis and mixed cellularity in cords and cystic formations. Mucous cells within nests are surrounded by squamous cells, and the entire structure is lined by a basement membrane.

Sample Findings

Less dense material with a double cell population of mucosal (secretory) cells and large squamous cells.

Ductal Carcinoma

A rare but very aggressive form that metastasizes to the lungs and bones; it is located in the parotid gland.

Sample Findings

Abundant cellularity with groups of cells and large branched papillary cells.

Adenocarcinoma

Usually asymptomatic, it metastasizes to regional lymph nodes. The mass is formed by glandular cells and signet-ring cells that grow into buds. There may be foci of necrosis and hemorrhage. Differential diagnosis may be challenging, involving metastatic gastrointestinal, lung, ovarian, thyroid, and breast carcinomas.

Malignant Mixed Carcinoma

There are two types:

• Malignant transformation of a prior benign lesion: Produces nodules and affects the facial nerve. There is malignant epithelial cell invasion of vessels and nerves, with areas of necrosis and hemorrhage.
• Malignant de novo: A lesion formed by malignant epithelial and mesenchymal cells.

This aggressive variety spreads to regional lymph nodes, lungs, abdominal organs, bones, and the spine.

Undifferentiated Carcinoma

A painful lesion that metastasizes to the liver, lungs, and lymph nodes. It presents with a variable pattern and cellularity, cellular atypia, and mitotic activity. Cells may appear in large groups or isolated; sometimes they are small, deep-seated, and associated with bleeding.