Overview of Adenoid Cystic Carcinoma

Executive Summary:

Adenoid Cystic Carcinoma (ACC) is the third most severe malignant tumor affecting the salivary glands. The experts have utilized various techniques and tests to diagnose Adenoid Cystic Carcinoma (ACC). Different tests and scans determines the extent of metastasis in other body parts. Adenoid Cystic Carcinoma diagnosis depends on the histologic analysis of a biopsy of the tumor specimen. The procedures used to diagnose Adenoid Cystic Carcinoma involves biopsy, imaging tests such as MRI, CT scan, and PET-CT scan. Radiographic imaging techniques such as computed tomography helps in diagnosing ACC recurrence.

Diagnostic approach of Adenoid Cystic Carcinoma

Adenoid Cystic Carcinoma (ACC) is a rare form of adenocarcinoma that can affect different body parts. But they are common in the head and neck region, particularly concerning the salivary glands. The other body sites where ACC can occur are the lungs, breast, uterus, eye, lacrimal gland, brain, trachea, Bartholin gland etc. Adenoid Cystic Carcinoma is the third most severe malignant tumor affecting the salivary glands besides Mucoepidermoid carcinoma and Polymorphous low-grade Adenocarcinoma (PLGA). Regarding Adenoid Cystic Carcinoma diagnosis, ACC shares many similar features with PLGA. When adenoid cystic carcinoma occurs in other sites (not in the salivary glands), they create a confusion of basaloid squamous carcinoma ^​1​. 

Techniques and tests to diagnose ACC

Doctors use several techniques and tests to diagnose Adenoid Cystic Carcinoma (ACC). They also conduct tests and scans to look for cancer spread or metastasis signs. Imaging tests can help determine whether the cancerous growth has spread to other body parts or not. Cancer diagnosis plays a significant role in deciding the best treatment plan for a patient’s condition.

The doctor may conduct a physical examination of the suspected area as a cancer diagnosis. But physical examinations may not give accurate results. A biopsy is the most preferred and sure way to detect any form of cancerous growth. A biopsy test confirms Adenoid Cystic Carcinoma. During a biopsy, the doctor or physician will take a tiny sample of tissue from the suspected area and send for testing in the lab. In some cases, a biopsy may not be possible, and in such cases, the doctor or the health care team may suggest other diagnostic tests and procedures.

The diagnosis mode varies from one person’s cancer condition to the other. The doctor may consider the following factors before choosing a particular diagnostic procedure:

• Suspected cancer type
• Signs and symptoms associated with the illness
• Age and general health condition of the patient
• Past medical history and tests

The histologic analysis of a biopsy confirms ACC. Adenoid Cystic Carcinoma has three major histologic growth patterns: tubular, cribriform, and solid. Radiographic imaging techniques such as computed tomography helps in diagnosing ACC recurrence ^​2​.

The procedures used to diagnose Adenoid Cystic Carcinoma, besides physical examination, include:

Biopsy

In a biopsy, the doctor will remove a small amount of tissue to examine under a microscope. A biopsy primarily helps in cancer diagnosis, as it gives definite results compared to other diagnostic procedures. A qualified pathologist examines the tissue sample sent to the laboratory. A pathologist is a doctor who specializes in analyzing and evaluating the models of cells, tissues or organs to diagnose disease or illnesses. The Adenoid Cystic Carcinoma can be complicated when it affects the salivary gland; hence, even an experienced pathologist may find it challenging to evaluate the tissue and diagnose it. A professional head and neck pathologist needs to examine the tissue sample to diagnose the condition accurately. 

There are different ways of performing a biopsy. The doctor may use a fine biopsy needle called fine-needle aspiration or FNA to extract a tissue sample. The thin needle removes cells and fluid from the suspected area in this procedure. Another method is the surgical removal of a part of the cancerous growth or tumor. In most cases of Adenoid Cystic Carcinoma, the diagnosis is made after surgically removing the growth or mass, which is initially considered benign. 

Imaging tests

Imaging tests can be instrumental in diagnosing cancer. The standard imaging techniques used by doctors to detect different disease conditions are Magnetic Resonance Imaging (MRI), Computed Tomography (CT scan) and Positron Emission Tomography (PET Scan). An MRI and CT scan can help doctors understand the location and dimension of the tumor before any surgical procedure. A PET scan can determine whether the cancerous growth has metastasized to other body parts or not. 

Magnetic Resonance Imaging (MRI)

This imaging technique uses magnetic fields instead of X-rays to produce precise, detailed images of the body and its parts. An MRI scan can also detect the site and size of cancerous growth. A special dye called a contrast medium is given before the scan to generate clear images. This dye can be either injected into the patient’s body via the vein or delivered orally in the form of a liquid or pill to swallow. Magnetic Resonance Imaging can also help identify perineural metastasis of Adenoid Cystic Carcinoma. Perineural metastasis refers to the growth and spread of cancer along the nerves.

Computed tomography (CAT or CT scan)

A CT scan differs from an MRI, as it uses x-rays to capture images of the body’s interior. The x-ray is taken from different angles. Computer combines the pictures to give a clear, detailed three-dimensional image that portrays any tumor growth or other abnormalities. Sometimes, a special dye called a contrast medium is given before the scan to ensure that the images captured are clear and crisp. This dye can be given intravenously or orally in a liquid or pill.

Positron Emission Tomography (PET) or PET-CT scan

A PET scan and a Computed Tomography or CT scan (PET-CT scan)can give better results. Since cancer cells are keen to use energy actively, they tend to absorb the radioactive sugar substance injected into the body. Once this happens, a scanner can detect this sugary substance and produce detailed, clear images of the body’s interior. 

After the diagnostic procedures (scans and tests), the doctor will analyze and review the test results in a detailed manner with you. If cancer is detected out of this Adenoid Cystic Carcinoma diagnosis, these test results can aid the doctor in describing the condition of cancer or tumor, which is called staging. A thorough understanding of the diagnosis can also help the doctor design a valid, workable treatment plan.

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