Acinic Cell Carcinoma - Causes, Symptoms, Diagnosis, and Treatment

Introduction:

Salivary gland cancer proliferates exponentially within thirteen to fifteen days. They invade the surrounding tissues, like muscles, nerves, and fascia. Most of the time, these growths exhibit irregular patterns and appear nodular. Therefore, acinic cell carcinoma shows a high metastatic rate. These carcinomas are the most common malignant tumors seen in the salivary glands.

What Is Acinic Cell Carcinoma?

The cells of the salivary glands are called acini cells. These acini cells are of two types - serous acini and mucous acini. They occur together in the salivary glands.

• Serous Acini: These cells are more granular because they contain amylase enzyme-secreting zymogen granules. These enzymes are essential for digestion.

• Mucous Acini: Unlike serous cells, the mucous acini produces a thicker or viscous secretion. These viscous secretions are rich in glycoproteins.

Acinic cell tumors are slow-growing tumors. Their rate of occurrence is less than ten percent. It most commonly involves the minor salivary glands. It originates from pure serous glands; hence, 85 percent of salivary gland tumors originate from serous glands. They are associated with lymphatic spread and hence show metastatic activity. Acinic cell carcinoma is the second most common parotid duct cancer. It starts around the fifth decade of life and is also associated with pediatric cases. It is more commonly seen in females than males. Mostly they occur unilaterally and are rarely seen in three percent of bilateral cases.

What Causes Acinic Cell Carcinoma?

The exact cause of acinic cell carcinoma is still unknown. However, factors like familial history, genetic mutation, exposure to chemicals, and workplace hazards like wood dust inhalation are some causes of the condition.

What Are the Types of Acinic Cell Carcinoma?

Based on their cell structure, they are classified into various types. Such as,

• Solid: It contains solid areas within the lesion. They are the most common types of carcinoma. They also occur together with numerous small cysts. These are polyhedral cells. No striated ducts are seen in the basophilic granular cytoplasm. The nucleus appears small and dark in color. Such solid tumors are locally excised with 10 to 15 percent metastasis occurrence. If metastasis is noted, chemotherapy is given.

• Microcystic: It contains cystic areas within the cytoplasm.

• Papillary Cystic: It contains cystic areas with papillary projections.

• Follicular: It resembles similar to thyroid tissue.

What Are the Symptoms of Acinic Cell Carcinomas?

Most of the symptoms of acinic cell carcinoma are not specific. Symptoms vary from person to person and depend upon the progression of the disease. Some of the symptoms are

• Facial paralysis.

• Swelling in the face.

• Stomach pain.

• Loss of appetite.

• Weakness.

• Diarrhea is seen in a few cases.

• Jaundice is associated with ductal adenocarcinoma.

• Increased secretion of lipase.

• Fat necrosis.

• Lymph node swelling.

• Metastasis to distant body parts like breasts, liver, and bone.

• Dark-colored urine.

• Indigestion.

• Pale-colored skin.

What are the risk factors for acinar cell carcinoma?

Acinar cell carcinoma risk factors include:

• Having acinic cell carcinoma or other kinds of salivary gland cancer in one's family.

• Being assigned female at birth.

• Having undergone radiation treatment for head and neck cancers other than acinic cell carcinoma.

• Working in a variety of fields, such as asbestos and rubber manufacture.

What Does a Microscopic Study of an Acinic Cell Carcinoma Show?

They are solitary lesions, slow-growing, and painless masses. They represent circumscribed, encapsulated, zymogen granules, uniform cells that show unusual mitotic activity on staining. They act as tumor cells. The basophilic cells show bubbles in them. The cells show the nucleus pushed to one end with a polygonal-shaped cell wall. The cytoplasm is granular with either eosinophilic or basophilic cells.

How Is Acinic Cell Carcinoma Diagnosed?

Diagnosis can be made with various tests such as

• Biopsy: This is done by collecting the tissue sample using fine needle aspiration cytology. It is a confirmatory test to diagnose acinic cell carcinoma.

• Histochemical Studies: This is done to study the morphological changes in the cell structure. Immunohistochemical stains are used to check for the presence of LMO2 in normal tissues and tumor cells. The cells displayed diffused cytoplasm in acinic cell carcinoma with LMO2 gene expression.

• Positron Emission Tomography (PET): This test helps diagnose any abnormality in the metabolic and biochemical function of the tissues and organs. It is done by using a radioactive drug to study the normal and pathological behavior of the cells.

• Computed Tomography (CT): This is done to visualize any change in the structure of the internal organ. It captures the image of bone, muscles, and deep tissues.

• Magnetic Resonance Imaging (MRI): This test is done by capturing the image of internal organs under a high magnetic field.

• Fluorescence in-situ Hybridization (FISH): It helps to identify the gene mutation as seen in ETS variant 6 (ETV6), causing the rearrangement of genes. A radio wave is generated to receive the image of internal structures.

What Are the Treatment Options for Acinic Cell Carcinoma?

Treatment of the disease depends on the progression of the tumor. Some of the treatments available are

• Surgical Resection: Removing the complete tumor surgically without leaving any negative tissue behind for further lesion progression. However, the chances of recurrence are high in this case.

• Radiotherapy: If the disease is spread to distal lymph nodes, then high radiation is induced at the tumor site.

• Chemotherapy: If the tumor cannot be removed surgically, high doses of chemicals in the form of drugs and incisions are done on the tumor site. Cisplatin, Oxaliplatin, Doxorubicin, Docetaxel, Capecitabine, and Irinotecan are commonly used drugs.

What Is the Prognosis of Acinic Cell Carcinoma?

The condition's prognosis depends upon the lesion's progress. The tumor size and rate of metastasis also determine the outcome. Almost six to ten percent of the population survives over five years. The mean survival rate is from 18 to 23 months.

Conclusion:

Most acinic cell carcinomas are slow-grade malignancies. If the lesion is detected in its initial stages, the morbidity rate can be extended up to ten years. The early detection of the tumor is made difficult due to its ignored symptoms. Rarely are children also diagnosed with this condition. Due to its malignant nature, regular follow-up is advised.