Introduction
Tumors that stay in their primary location and do not invade other body parts are called benign tumors. They do not metastasize to local structures or peripheral parts of the body. They do not cause any problems usually. Genetics and environmental toxins are associated with a benign tumor's growth. Choristoma is a rare type of benign tumor that consists of tissues derived from germ cell layers not belonging to that body site. They have been classified based on the type of tissue. They sometimes begin within the oral cavity, skin, or internal organs.
Various pathologies should be differentiated before concluding as choristoma, which is as follows:
A dermoid cyst comprises the epidermis and dermis's constituents, including hair. Choristoma involving the oral cavity may contain parts of the epidermis like skin, hair follicles, sebaceous glands, bony components (osseous), gastric, cartilaginous, lingual thyroid, respiratory, salivary, or glial tissue. Almost 70 percent of lingual osseous and cartilaginous choristomas can be observed in females. Choristoma most commonly affects adults but can affect individuals of all ages.
What Are the Types of Choristoma?
Various types of choristoma have been mentioned below:
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Phakomatous Choristoma: It involves the eyelid or orbit and contains embryological precursor cells of the lens known as lenticular anlage.
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Epibulbar or Corneal Choristoma: It appears at the limbus of the eye and can contain dermoid tissue, lipodermoid, or other types of tissues.
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Choristoma Involving the Ear Canal: This type usually contains cartilage.
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Salivary Gland Choristoma: Reports show that it is present on the anterior chest wall and breast.
Who Is At Risk Of Getting Choristoma?
Anyone can get choristoma ranging from birth up until old age. Epidermal choristomas have been reported mostly in males. Most of the patients affected with lingual osseous choristoma have been reported in females. Mostly it is seen in the third and fourth decades. Salivary gland choristoma and phakomatous choristoma are observed in newborns.
How Is It Caused?
Choristoma is a developmental abnormality. It is developed from germ cells. Some symptoms are presented late in life in a few cases. One of the theories is that it may be caused due to chronic irritation.
What Are the Signs and Symptoms of Choristoma?
The signs and symptoms depend on the type of choristoma. They have been explained below:
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Epidermal choristoma is observed on the dorsum of the tongue and mostly seems to be a macule that is brown to black with a variable size of 3 to 11 mm (millimeter). A few other conditions can mimic this condition. They are congenital melanotic macules and melanocytic nevus.
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Osseous choristoma is seen as a pedunculated, hard lump that is painless. It is present on the dorsum of the tongue and posterior to the foramen caecum. The oral type of choristoma can also be seen on the buccal mucosa or gingiva.
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Phakomatous choristoma is similar to other types but seen around the orbit or eyelid region. Rhabdomyosarcoma should be ruled out.
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A choristoma in the auditory canal presents as a mass that can cause hearing loss and lead to an ear infection.
How Can It Be Diagnosed?
When visiting a physician, report the signs and symptoms, medical history, personal history, and family history. After this, the physician will do a physical examination and certain tests. It can be diagnosed with the help of excision or biopsy in which histological features are observed, confirming microscopically normal cells in an abnormal site.
Oral choristomas are classified based on the types of tissues they comprise, which are as follows:
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Salivary gland choristoma.
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Central.
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Gingival.
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Cartilagenous choristoma.
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Osseous choristoma.
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Glial choristoma.
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Lingual thyroid choristoma.
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Lingual sebaceous choristoma.
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Gastric or respiratory mucosal choristoma can be solid or cystic.
How Can It Be Treated?
Choristoma is usually managed surgically. The benign tumor is excised, and a histopathological examination is done to confirm the diagnosis.
How Is The Prognosis?
As the lesions are benign, there is little risk of transformation into malignancy. The recurrence rates after surgical excision are very low.
What Is the Difference Between Hamartoma Versus Choristoma?
Hamartomas are defined as an overgrowth of mature tissues normally observed in any body site, but they are not organized properly, and often, one element is predominant. However, choristomas are a mass of tissue that is normal histologically for a part of the body other than the one in which it is situated, heterotopic or ectopic.
What Is the Differential Diagnosis?
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Pleomorphic Adenoma: It is the most commonly observed salivary gland tumor with osteocartilaginous foci. It is also called a benign mixed tumor as it is of dual origin from epithelial and myoepithelial elements. It constitutes up to two-thirds of all tumors of the salivary gland. Although it is benign, it can also transform into malignancy and may have a recurrence.
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Cartilaginous Metaplasia: This condition is commonly observed in soft tissues below ill-fitting dentures. It presents as diffuse calcium deposits with scattered cartilaginous cells arranged in different stages of maturation in single or clustered foci.
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Salivary Gland Tissue: Salivary glands are responsible for the production of saliva. There are three major salivary glands and numerous minor salivary glands. Choristomas do not have salivary gland ductal or myoepithelial components which is a differentiating factor from normal salivary gland tissues.
Conclusion
Choristomas are benign tumors that form in areas other than the parent site of the germ cell layers. It is classified based on the site of occurrence. The management comprises excision. Consult a specialist online with the help of online medical platforms to know more about this condition.
