Types of Mesenchymal Benign Oral Tumors

Introduction

Mesenchymal tumors are referred to as such because they primarily consist of fibrous connective tissue, smooth muscle, skeletal muscle, blood, lymphatic vessels, adipose tissue, and peripheral nerve tissue. Benign mesenchymal tumors frequently occur in the oral cavity and typically present as well-circumscribed lesions (though rarely some lesions may be poorly circumscribed). These lesions tend to exhibit slow growth, persistence, and non-tenderness. Nearly 95 percent of these soft tissue enlargements in the oral cavity are considered for surgical treatment or excision biopsy by oral surgeons.

What Are the Different Types of Oral Benign Tumors?

The different types of oral benign tumors are:

1. Irritation Fibroma: These are common reactive soft tissue lesions or enlargements that occur in response to chronic irritation or traumatic forces on the oral mucosa. These lesions present exophytic, dome-shaped, and firm or compressible masses in the oral cavity. The oral mucosa overlying these lesions may appear normal or frequently ulcerated due to underlying oral trauma. Further, it is very common for these lesions to affect either the buccal (near the cheek) or labial (towards the lip) mucosa in the oral cavity.

2. Epulis Fissuratum (Inflammatory Fibrous Hyperplasia): It is a condition characterized by hyperplasia (increased number of cells) of dense connective tissue in the oral cavity. It is usually caused by chronic oral irritation from denture edges. The enlargement commonly affects the oral vestibule (a space between lips and cheeks) and is characterized by fissures that correspond to the surface of the denture.

3. Peripheral Ossifying Fibroma (Peripheral Fibroma): These are reactive soft tissue tumors and are commonly found on the gingiva (gums) or attached alveolar mucosa. They may present as ulcerated lesions with a pinkish-to-red mucosal color. These tumors are most frequently observed in adolescents or young adults. Microscopically, a notable feature is the formation of a mineralized product within the fibrous stroma, which aids in their characteristic diagnosis.

4. Schwannoma: This benign neoplasm affects the Schwann cells (a type of non-neuronal cells). The tumors are not only firm but also encapsulated, exhibiting a freely movable consistency. Recurrence of these tumors is uncommon following surgical excision.

5. Neurofibroma: These benign neoplasms affecting the Schwann cells are known as neurofibromas. They can occur as solitary lesions. In the case of multiple neurofibromas, they manifest in various areas of the oral cavity. These lesions are typically fixed to the surrounding structures and exhibit a firm or compressible tendency when felt by the dentist.

6. Traumatic Neuroma: These benign tumors are considered to be a reactive proliferation of nerve bundles following nerve amputation. They can occur in cases of traumatic amputation of nerves, particularly in large peripheral nerve-based areas such as the tongue and lower lip. These lesions may cause pain upon palpation. Also, multiple neuromas unassociated with trauma are typically characteristic of multiple endocrine neoplasia (MEN, inherited endocrine system disorder) type 2B syndrome.

7. Granular Cell Tumor: These benign neoplasms or tumors are also known as granular cell myoblastomas. The tumor cells originate from Schwann cells. In these tumors, the lesions are attached or fixed to the surrounding local structures, with the most common location being the dorsum of the tongue. Microscopically, these lesions exhibit an extremely infiltrative nature into the surrounding tissues.

8. Rhabdomyoma of the Oral Mucosa: This is a rare benign neoplasm originating from skeletal muscles. These tumors are exclusively located in areas where skeletal muscle is present, with the tongue being a common site. Furthermore, these tumors are fixed to the surrounding structures or local tissues.

9. Congenital Epulis: This is a benign soft tissue enlargement that primarily affects the attached alveolar mucosa in young infants. Approximately 90 percent of these lesions occur in female infants.

10. Peripheral Ossifying Fibroma: These are reactive soft tissue lesions or enlargements that typically occur on the gingiva or attached alveolar mucosa in the oral cavity. Microscopic evaluation of these tumors reveals giant cells that are identical to those typically found in central giant cell granuloma infections.

11. Pyogenic Granuloma: These are soft tissue enlargements or reactions that occur in response to minor oral injury or oral mucosal irritation. They can be found on any oral mucosal surface, potentially affecting any age group. However, they are most commonly observed on the gingiva in children and females during pregnancy. Pyogenic granulomas have a characteristic compressible, lobulated, and pedunculated appearance. These lesions frequently present with ulcerations, and their initial growth rate in the oral cavity is quite rapid.

12. Lymphangioma: These are benign developmental overgrowths that occur in the lymphatic vessels and are therefore not true neoplasms. However, they can be quite discomforting as they present on the neck or tongue, leading to difficulties with breastfeeding, eating, and speaking for infants. This condition primarily affects infants below two years of age. The lesions on the tongue are compressible and fixed to the surrounding structures.

What Is the Management of Mesenchymal Lesions/Benign Tumors?

The focus of oral and maxillofacial surgeons is not only to relieve patient discomfort and prevent the potential aggravation of benign tumors but also to establish a long-term successful prognosis to prevent tumor recurrence. Microscopic diagnosis plays a crucial role in differentiating between various types of oral lesions or tumors. The prognosis for benign tumors is usually excellent. However, tumors such as pyogenic granuloma and peripheral ossifying fibroma may have a possibility of recurrence. Therefore, excision biopsy and surgical removal of these benign tumors help in the complete elimination or management of the tumor site. In the case of recurring tumors of mesenchymal origin, the treatment typically involves re-excision. However, treatment approaches may be modified during pregnancy or in cases involving early childhood lesions. Unless the benign tumors cause airway obstruction, it is generally not recommended to treat such lesions in infancy or pregnancy due to the increased risk of hemorrhage in such cases.

Conclusion

To conclude, although benign tumors may be asymptomatic, they can still cause patient discomfort and have the potential to progress into severe lesions or neoplasms, especially if the underlying causative factor or trauma is left untreated. Timely diagnosis and surgical management of these tumors can lead to an excellent long-term prognosis for affected patients.