Adenoid cystic carcinoma is the second most common malignant tumor of salivary gland overall (after mucoepidermoid carcinoma).

It represents 27% of malignant submandibular gland tumors, making it the single most common malignant salivary gland tumor in this region.

Clinical features

• Early lesions of the major and minor salivary glands present as painless mass near the mouth, jaw and below the ears usually growing slowly.
• Advanced and long standing tumors present with pain and/or nerve paralysis due to invasion of peripheral nerves by the tumor.
• Tumors of the lacrimal gland may present as proptosis, swelling of eye lids and changes in vision.
• Tumors arising in the trachea and bronchus present with respiratory symptoms like hoarseness of voice, cough with expectoration, hemoptysis.
• Tumors arising in the larynx may lead to changes in speech.

Tests and diagnosis

• Diagnosis mainly by biopsy and histology
• Three major histologic growth patterns are noticed of cribriform, tubular and solid.
• The solid pattern is associated with a more aggressive disease course.
• There are no serum markers for this neoplasm.
• Recurrences are usually identified CT scan.

Differential diagnosis

• Benign mixed tumor of salivary gland
• Mucoepidermoid carcinoma
• Polymorphous low-grade adenocarcinoma

Treatment

Surgical resection is the main stay of treatment, advocate post operative neutron beam radiotherapy to limit the local recurrence

Chemotherapy less effective in unresectable and metastatic disease

Relatively new chemotherapeutic drugs (paclitaxel, gemcitabine, etc.) alone, or in combination with other drugs, in the control of metastatic or locally recurrent tumors

Prognosis

• Most patients with adenoid cystic carcinoma, survival rate is 5 years, only to have tumors recur and progress.
• Another unusual feature of this tumor is that, unlike most carcinomas, it seldom metastasizes to regional lymph nodes.
• Distant metastasis is the most common presentation of treatment failure.
• The lung is by far the most common site of metastasis, with the liver being the second most common site. Bone metastases usually indicate a fulminant clinical course.
• Poor prognostic factors are a solid growth pattern, Perineural invasion of major nerves and/or positive margins after histopathologic examination.