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

• Abrikossoff Tumor
• Granular Cell Myoblastoma
• Granular Cell Schwannoma

What is Granular Cell Tumor? (Definition/Background Information)

• Granular Cell Tumor (GCT) is a common benign tumor of the soft tissue, which can occur anywhere in the body
• Some researchers note that Granular Cell Tumor may be a tumor of neural origin (relating to a nerve)
• In a majority of the cases, the tumor is present as a single nodule; though rarely, the tumor can occur as multiple nodules too
• These tumors have also been noted to be present from birth (congenital presentation)

Who gets Granular Cell Tumor? (Age and Sex Distribution)

• Granular Cell Tumor can affect an individual at any age, but is usually seen between the ages of 30 and 50 years. It is rarely observed in children
• Both males and females are affected by Granular Cell Tumor; though it is more common in females than males (a 3:1 female-male incidence ratio is observed)
• The tumor is more commonly seen in the African American population as against the Caucasian population

What are the Risk Factors for Granular Cell Tumor? (Predisposing Factors)

No documented risk factors have been reported for Granular Cell Tumor, however:

• Though Granular Cell Tumors do not usually run within families, rare cases of increased incidence within families, have been reported

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones 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 Granular Cell Tumor? (Etiology)

• The exact cause of Granular Cell Tumor is unknown
• Researchers have documented certain genetic changes within the tumor. However, cases where these specific genetic mutations have been observed are rare. Thus, studies regarding genetic changes are limited
• GCT is not associated with any known congenital syndrome

What are the Signs and Symptoms of Granular Cell Tumor?

The signs and symptoms of Granular Cell Tumor are:

• Granular Cell Tumors are usually presents as a single nodule under the skin. Rarely, the tumor can occur as multiple nodules too. About 1 in 10 individuals with GCT may have multiple tumors on the body
• Sometimes, the tumors have been observed to be present at birth
• The skin nodules are not painful. However, infrequently these may be itchy and painful to touch. The nodule is typically less than 3 cm in size (along the larger dimension)
• The skin over the nodule may be brownish red and is usually intact. The tumor usually occurs in the subcutaneous tissue
• A majority of the cases are observed in the head and neck area (70%), with the most common location being the tongue (30%)
• The remaining 30% of the tumors can occur on any other part of the body, and these include the breast, arms, and legs
• Cases have been reported where the tumor has occurred on the walls of the larynx and trachea (wind pipe and food pipe), parotid glands, small and large intestine, and anal region

How is Granular Cell Tumor Diagnosed?

A Granular Cell Tumor is a slow-growing tumor underneath the skin. If the tumor occurs in non-skin areas then the diagnosis is usually more difficult to make, since the tumor is not readily visible to the eye. Granular Cell Tumor is diagnosed using the following methods:

• Complete physical examination and a thorough medical history
• Imaging studies (as necessary)
• A biopsy of the nodule: The biopsy is sent to a laboratory, where the pathologist examines the nodule under a microscope, to arrive at a conclusive diagnosis

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 Granular Cell Tumor?

There are usually no complications arising due to a benign Granular Cell Tumor. However, some complications could include:

• The Granular Cell Tumor may become malignant, even though this is a rare possibility
• A malignant GCT can metastasize to other regions of the body. Extensive metastasis may result in a fatality

How is Granular Cell Tumor Treated?

The treatment measures for Granular Cell Tumor include:

• Complete surgical resection of the tumor is usually curative
• Occasionally, based upon the location of the tumor, complete removal of the tumor may be difficult. In such cases, the tumor may recur
• Sometimes, it is difficult to distinguish between a benign GCT and a malignant GCT. Hence, a complete removal of the tumor is recommended

How can Granular Cell Tumor be Prevented?

• The cause of Granular Cell Tumor is unknown; hence, there are no known methods to prevent the tumor occurrence
• Early diagnosis with close monitoring, and treatment of the tumor is important

What is the Prognosis of Granular Cell Tumor? (Outcomes/Resolutions)

• The prognosis of a benign Granular Cell Tumor is excellent
• If the tumor is incompletely removed, a benign tumor may have local recurrence

Additional and Relevant Useful Information for Granular Cell Tumor:

• Benign Granular Cell Tumors are also found within the muscles, tendons, ligaments, soft tissues, and rarely within lymph nodes. Presence of GCT within the lymph nodes is a difficult problem for the doctors. This is because it is difficult to tell whether the presence of such tumors in the lymph nodes are due to a metastasis from a different body site, or if the GCT originated within the lymph nodes itself (primary site)
• The Granular Cell Tumors should be clinically and histologically distinguished from other tumors. These tumors include rhabdomyoma, hibernoma, fibroxanthoma, neurofibroma and schwannoma.  A pathologist will help eliminate other tumor types
• Sometimes, the pathologist may perform special studies, which include immunohistochemical stains and histochemical stains. The common immuno stains used are S100 protein, Neuron Specific Enolase (NSE), calretinin, peripheral myelin protein, Myelin Basic Protein (MBP), alpha 1 antitrypsin protein, CD68, and vimentin. These immuno stains are usually positive in Granular Cell Tumors. The GCTs are negative for neural filaments and GFAP immunostains
• The tumors are positive for PAS histochemical stains when examined by the pathologist under a microscope. Even though the tumors are positive for PAS stain, the tumors do not contain glycogen

There are two variants of Granular Cell Tumor and these include:

Granular Cell Epulis of Infancy:

• Granular Cell Epulis of Infancy. This is a rare tumor that occurs on the gums of the newborn. It is more common in females. A pathologist would be able to arrive at a diagnosis of Granular Cell Epulis of Infancy after examination under microscope and also after performing a variety of special studies called immunostains. This tumor is negative for S100 protein, Neuron Specific Enoloase (NSE), laminin and, Myelin Basic Protein (MBP), CD-57 and alpha-1 antitrypsin protein. The above stains show a pattern that is different from the staining pattern of a classical Granular Cell Tumor.  This difference in staining pattern helps in the correct diagnosis
• This tumor is usually slow-growing. The tumor does not grow after birth and there is no tendency for local recurrence. In majority of cases a congenital Granular Cell Tumor would either stop to grow or completely disappear without treatment
• This type of tumor tend to be smaller size compared to traditional soft tissue tumor (about 1 cm along the larger dimension)
• There are no documented cases of a congenital Granular Cell Tumor undergoing a malignant transformation to develop into a malignant Granular Cell Tumor

 Malignant Granular Cell Tumor:

• Malignant Granular Cell Tumor is a very rare variant of the Granular Cell Tumor. Less than 1 in 50 GCTs would have tendency to become malignant. Malignant Granular Cell Tumor can occur at any age, but is more commonly seen in ages between 30-50 years. It is also more common in females, than males. Unlike benign Granular Cell Tumor, which is more common in head and neck region; the malignant variant of GCT is more common in the arms and legs (particularly common in the thigh region). Unlike benign Granular Cell Tumors, the malignant tumors grow more rapidly
• The skin over the malignant Granular Cell Tumor could often break, causing ulceration. The tumor can spread to the surrounding areas through infiltration, and spread to other distant regions of the body too (metastasis)
• When examining a biopsy of the tumor, a pathologist and would be able to distinguish benign Granular Cell Tumor from a malignant one, after examination under a microscope. Normally, a malignant Granular Cell Tumor would have a higher amount of abnormal cells and increased proliferation (growth). Clinical correlation is very important to arrive at a diagnosis of malignant Granular Cell Tumor. A malignant Granular Cell Tumor may show the following features: Size greater than 3 cm (along the larger dimension), ulceration of overlying skin, and a rapid increase in size