What are the other Names for this Condition? (Also known as/Synonyms)

• Basaloid Adenocarcinoma of Salivary Gland
• Congenital Hybrid Basal Cell Adenoma-Adenoid Cystic Carcinoma of Salivary Gland
• Embryoma of Salivary Gland

What is Sialoblastoma? (Definition/Background Information)

• Sialoblastoma is an extremely rare tumor affecting the salivary glands that is typically manifested at birth. In many cases, the tumor affects the parotid gland (major salivary gland), and it can be potentially aggressive
• The cause of formation of Sialoblastoma is unknown, and currently, no known methods exist to prevent occurrence of the tumor
• Most tumors are solitary, small, and asymptomatic; though the larger ones may compress the surrounding structures and cause related signs and symptoms
• The diagnosis of Sialoblastoma can be confirmed through a tissue biopsy. The treatment is a complete surgical removal of the tumor with adequate margins
• The prognosis of Sialoblastoma is excellent in most cases, following surgery to remove them. However, it is a low-grade malignant tumor, and in case of metastasis, the prognosis may be unpredictable

Who gets Sialoblastoma? (Age and Sex Distribution)

• Sialoblastoma is a congenital tumor that is usually diagnosed at birth or shortly following birth. Infrequently, it has also been diagnosed in children after age 2 years
• Both males and females are affected. Some reports inform that the tumor may be more common in males
• It is seen worldwide and all races and ethnic groups may be affected

Currently, only a few cases of Sialoblastoma have been reported worldwide. Since the tumor is uncommon, there is only limited information available in the medical literature.

What are the Risk Factors for Sialoblastoma? (Predisposing Factors)

• Currently, no clearly identified risk factors for Sialoblastoma have been established.
• In rare cases, the tumor has been associated with congenital nevus, hamartoma of skin, and hepatoblastoma

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Sialoblastoma? (Etiology)

• Currently, scientists do not know the factor(s) causing Sialoblastoma
• It is believed to arise from embryological remnants (displaced tissue) during fetal growth and development

What are the Signs and Symptoms of Sialoblastoma?

The signs and symptoms of Sialoblastoma may include:

• Presence of a tumor mass (bulge) by the side of the cheek
• The tumor size may range from 1-15 cm, with a majority measuring around 3 cm
• In some cases, following birth, a rapid increase in tumor size may be noted
• Large tumors may cause skin ulceration
• Most tumors are confined to the major salivary glands (parotid glands, in about 70% of the cases). The submandibular glands are affected second most commonly
• In about 5-10% of the cases, the minor salivary glands may be involved
• Large tumors may present difficulty in feeding the baby
• Tumors that behave malignantly may invade the nerves (nerve invasion) and blood vessels (angiolymphatic invasion). In such cases, tumor necrosis may be seen

Small tumors usually do not cause any symptoms. But, they may become painful, if surrounding structures are compressed.

How is Sialoblastoma Diagnosed?

The following exams and procedures may be used in the diagnosis of Sialoblastoma:

• Evaluation of the child’s family medical history and a through physical and oral examination
• Plain X-ray of the head and neck region
• Ultrasound scan of the affected salivary gland
• CT or MRI scans of the head and neck region
• Prenatal ultrasound scan may help visualize the tumor, even before the child is born

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include: 

• Fine needle aspiration (FNA) biopsy of the tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy may be recommended.
• Salivary gland core biopsy of the tumor
• Salivary gland open biopsy of the tumor

Tissue biopsy:

• A tissue biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
• Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
• Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

A differential diagnosis may be undertaken to exclude other tumors such as:

• Rhabdomyosarcoma
• Adenoid cystic carcinoma

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Sialoblastoma?

The complications due to Sialoblastoma may include:

• The tumors are known to recur following surgical procedures to remove them; a recurrence rate of approximately 25% is noted. Most tumors recur within 2 years of surgery
• Tumor metastasis to regional sites (lung and cervical lymph nodes) has been observed in about 1 in 10 cases
• Surgery to remove the tumor mass may result in facial nerve palsy (surgical complication)
• Post-surgical wound infection

How is Sialoblastoma Treated?

• A complete surgical excision with clear margins is the preferred mode of treatment of Sialoblastoma. This can result in a cure
• Additional treatment modes, such as radiation therapy and chemotherapy, may be recommended based on the healthcare professional’s assessment of tumor behavior
• Post-operative care is important: One must maintain minimum activity levels, until the surgical wound heals
• Long-term follow-up is required, because recurrence at the site of surgery have been reported many years after surgery

How can Sialoblastoma be Prevented?

• Current medical research has not established a method of preventing the formation of Sialoblastomas
• Regular medical screening at periodic intervals with blood tests, radiological scans, and physical examinations, for those who have already endured the tumor, are helpful

What is the Prognosis of Sialoblastoma? (Outcomes/Resolutions)

• In a majority of cases, following surgery to remove the tumors (complete resection), the prognosis of Sialoblastoma is excellent, since it behaves in a benign manner
• However, tumor recurrences may be seen in up to one-fourth of the cases, and metastasis is observed in about one-tenth of the cases. The prognosis of the tumor with metastasis may be guarded; deaths have been known to occur

The prognosis of Sialoblastoma may depend upon a set of several factors, which include:

• Behavior of the tumor; whether it behaves in a benign or malignant manner
• The surgical respectability of the tumor (meaning, if the tumor can be removed completely)
• Health status of the child: Children with overall excellent health have better prognosis compared to those with poor health
• Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have poorer prognosis compared to tumors that do not recur

As with any tumor, it is important to have follow-up appointments with a physician to monitor for any returning tumors.

Additional and Relevant Useful Information for Sialoblastoma:

There are 3 major types of salivary glands and these include the following:

• Parotid glands, found on the sides of the face
• Submandibular glands located at the back of mouth, on both sides of the jaw
• Sublingual glands that are seen under the floor of the mouth

The salivary glands produce saliva that helps in:

• Lubricating the mouth
• Swallowing
• Protects the teeth against bacteria
• Digestion of food