Principles of neoplasm classification
Due to the complex embryological development of the face, tumors exhibit great morphological diversity. Globally, they are divided into two groups:
- Organ-specific — originate from tissues characteristic of the face (odontogenic, glandular, mucosal squamous epithelium).
- Non-organ-specific — arise from universal structures (skin, soft and bone tissues).
There is no universally accepted base, but most physicians follow the WHO classification (by location, histology, and degree of malignancy). According to the clinical course (A.I. Paches classification), tumors are divided into benign, malignant, and intermediate (locally destructive) neoplasms.
Oncological vigilance and examination
Primary diagnosis rests with dental practitioners. They are required to thoroughly examine every patient. The examination is performed strictly according to the protocol:
- External inspection: evaluation of the skin and salivary gland areas.
- Oral cavity: lips (first closed, then everted), vestibule, cheeks (mandatory under artificial lighting).
- Tongue and floor of the mouth: the tongue is forcibly pulled out, hard-to-reach areas are examined with a mirror.
- Palpation: a mandatory step. The cheeks and lateral pharyngeal wall are palpated bimanually, assessing the salivary glands and lymph nodes.
Benign odontogenic jaw tumors
These organ-specific lesions are related to the development of the dentition. The most common representatives are:
- Ameloblastoma (adamantinoma): An epithelial tumor resembling the enamel organ of a tooth. Despite being benign, it exhibits invasive growth. It most commonly affects the mandible (angle, ramus) in individuals aged 20–40. It can cause facial asymmetry, and when the bone becomes thinned, the "pervenche crackle" (parchment crackle) sign can be palpated. On radiographs, the polycystic form features a characteristic scalloped border.
- Odontoma: A hamartomatous malformation of dental tissues. It can be compound (tooth-like structures) or complex (chaotic conglomerate). Surrounded by a capsule. Sometimes it can "erupt" beneath the mucosa, causing ulceration and mimicking pericoronitis.
- Cementoma: A connective tissue tumor differentiating into cementum. Often tightly fused to tooth roots. Grows slowly, deforming the jaw.
Approaches to surgical treatment
Tactics depend on the tumor type and its tendency to recur:
- For ameloblastoma: Simple curettage (excocochleation) results in recurrence in 90% of cases, and radiation therapy is ineffective. Resection with a 10–15 mm margin into healthy tissue is necessary. For small lesions of the mandible, conservative resection according to P.V. Naumov is used (with suturing of the masseter muscle m. masseter to stimulate regeneration).
- For odontomas and cementomas: The tumor is removed along with its capsule, and the adjacent bone is treated with a bur or curette. If the odontoma is fully calcified and asymptomatic, active surveillance is an option.
Briefly: answers to topical questions
What are the radiologic signs of mandibular ameloblastoma?
Radiological signs of ameloblastoma depend on its form and are characterized by bone tissue destruction.
- Solid form — defined by a round or irregularly round zone of destruction with clear margins.
- Polycystic form — multiple round foci of bone radiolucency are revealed, which merge with each other and are separated by bony septa.
- Even when the bony septa are destroyed, the scalloped border of the radiolucent lesion is preserved.
- On the radiograph, the bone appears expanded; multi-locular zones may resemble "soap bubbles".
- The true dimensions of the tumor may exceed the visible radiological boundaries by 0.5–0.7 cm.
What is the surgical technique of P.V. Naumov's conservative mandibular resection?
The surgical technique of P.V. Naumov's conservative resection involves removing the tumor within healthy tissue while strictly preserving bone continuity. The operation is indicated for small lesions in the region of the angle and ramus of the mandible, provided its lower border remains unaffected and has a thickness of at least 0.5 cm. The main surgical feature is that the resulting bone defect is filled with muscles. The masseter (m. masseter) and medial pterygoid (m. pterygoideus medialis) muscles are sutured to the angle of the jaw and fixed with stitches. This stimulates and enhances the bone tissue regeneration process.
What histological types of ameloblastoma are distinguished according to the WHO classification?
A direct indication of the WHO criteria for ameloblastoma types is absent, but the following histological variants of its structure are distinguished:
- Follicular variant — the most typical, represented by islands of epithelial cells.
- Plexiform variant — strands of epithelium with irregular outlines, intertwining to form a network.
- Acanthomatous type — has the highest tendency to recur.
- Granular cell variant — belongs to the rare forms.
- Monocystic variant — a tumor within a cyst wall, has the best prognosis.
Desmoplastic, squamous cell, and basal cell variants are also distinguished. Different histological types can be found simultaneously within a single tumor.
What specific diseases must ameloblastoma be differentiated from?
Differential diagnosis of ameloblastoma must be carried out with jaw cysts, tumor-like processes, and other neoplasms. The disease is differentiated from the following specific pathologies:
- Jaw cysts — follicular and radicular cysts.
- Inflammatory diseases — chronic periodontitis (in remission) and chronic osteomyelitis.
- Bone tumors — osteoclastoma (osteoblastoclastoma), osteoma, fibroma, and myxoma.
Diagnosis based solely on clinical manifestations is very difficult, as ameloblastoma visually and symptomatically mimics other benign and malignant jaw pathologies.
What types of cementomas are distinguished according to the International Histological Classification?
The sources do not provide a classification of cementomas according to the International Histological Classification. Within the group of "cementum tumors" (cementomas) related to fibro-osseous-cemental lesions of the jaws, the following are indicated:
- Cementoblastoma (true cementoma).
- Cementing fibroma.
- Periapical cemento-dysplasia.
The group includes lesions of both neoplastic and non-neoplastic nature; a common feature is the presence of cementum-like tissue.
The most frequent benign odontogenic tumors are easy to remember by the acronym AOC: Ameloblastoma, Odontoma, Cementoma.
Class and exam questions
Why is ameloblastoma difficult to diagnose based on clinical presentation alone?
It mimics many other pathologies (cysts, tumor-like processes, other benign, and even malignant neoplasms). A definitive diagnosis is established only after a biopsy.
What is the "crepitation" ("parchment crunch") sign?
This is crepitus, which is determined upon palpation of the thinned bone wall of the jaw overlying a growing tumor (e.g., ameloblastoma).
Are teeth always extracted in the presence of a cementoma?
Yes, if the tooth is tightly fused to the tumor node (which is characteristic of most cementomas), it must be removed along with the neoplasm.
What else to study on this topic
- Radiological classification of ameloblastomas according to Yu.A. Zorin
- Differences between solid and polycystic forms of ameloblastoma on radiographs
- Periapical cemental dysplasia and gigantiform cementoma (tumor-like forms)
- Types of surgical interventions: resection, exarticulation, ecochleation
- Rare odontogenic tumors (ameloblastic fibroma, myxoma)
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