Abnormal proliferation of bone fibers, also known as osteofibrous dysplasia, is a disorder in which normal bone tissue is gradually replaced by proliferating fibrous tissue, either in a single or multiple bones. Although it is not a true tumor, it has some of the characteristics of a bone neoplasm. It is currently classified as a neoplasia-like disorder and is considered a disorder of ossification during bone growth and development. It is not a rare clinical condition, accounting for approximately 25% of all bone neoplasms and 7% of all benign bone tumors [1]. This disease, especially the single bone type, is mainly resected surgically, and the excess bone is mostly removed by bone knife, chainsaw, and grinding drill, and there is often no clear standard and specific index for clinical revision, and it is mostly performed with reference to the normal lateral jaws and the operator’s own experience.
I. Case introduction
The patient was male, 34 years old, farmer. He was admitted to the hospital on March 17, 2004, mainly because of a painless mass in the right mandible for 20 years.
History: The patient was unintentionally found to have an enlarged right mandibular angle by his teacher when he was in school in 1989. Later, the swelling grew and developed to the left and right ascending branch without any discomfort. In the first month of 2004, he felt numbness in his left jaw, which improved after infusion (medication unknown). There was a history of chewing pain. In view of the growing swelling, he came to our hospital for treatment on February 24, 2004. He was admitted to our hospital today with a “mandibular swelling”. Since the onset of the disease, he had good mental health, diet and sleep, and normal bowel movements.
Past history: He is physically fit. He denies any history of heart disease, hypertension, diabetes, stomach disease, hepatitis, tuberculosis, etc. No history of trauma, surgery or bleeding. History of drug and food allergy denied. History of vaccination is normal.
Personal history: origin Hebei. No history of exposure to epidemic water, radioactive materials, chemical toxins. Married at age 23, wife is healthy. He has a son who is in good health.
Family history: Father died of lung cancer in 1992, mother died of mental illness in 2003. Brother and sister are healthy. Denies any family history of similar or hereditary diseases.
Physical examination
Body temperature: 36.5°C, pulse: 72 beats/min, respiration: 16 breaths/min, blood pressure: 18.0/10.3 kPa (135/75 mmHg). Development was normal, good nutrition, clear consciousness, automatic position, cooperation in physical examination, clear language, and tangential answers. The skin color was normal, with no yellow staining or bleeding spots. No enlargement of superficial lymph nodes was palpable throughout the body. There was no cranial deformity. The eyes were not protruding, the eyelids were not puffy, the conjunctiva was not congested, the sclera was not yellowish, the pupils were equally large and round, the reflex to light was sensitive, and the visual field was not defective by hand measurement. There was no deformity of the auricle, no purulent discharge from the external auditory canal, and no pressure pain in the bilateral mastoid process. The nasal cavity was clear, no purulent secretions were seen, and there was no pressure pain in the paranasal sinus area. Oral and maxillofacial details were seen in the specialist. The neck was soft, with no jugular vein irritation or arterial pulsation. The trachea was centered and the thyroid gland was not large. There was no deformity of the thorax, the respiratory motion was bilaterally symmetrical, the fibrillation was consistent on both sides, and the percussion of both lungs was clear. Breath sounds were clear in both lungs, and no dry or wet rales or pleural friction sounds were heard. The precordial region was not elevated, the apical pulsation was not obvious, and no tremor was palpable. The cardiac border was not large. The heart rate was 72 beats per minute, and the rhythm was uniform. No murmurs or pericardial friction sounds were heard in the valve auscultation areas. The radial artery and dorsalis pedis artery pulsations were equal bilaterally. The abdomen was flat and soft, no mass was found, and there was no pressure pain or rebound pain throughout the abdomen. The liver and spleen were not palpated under the ribs. There was no percussion pain in the hepatic region, and the superior hepatic border was located at the fifth intercostal space in the right midclavicular line. There was no percussion pain in both kidney areas. Mobile turbid sounds were negative, and bowel sounds were normal. The anus and external genitalia were not examined. There was no deformity of the spine, no pressure pain and percussion pain. There was no deformity of the extremities, no redness, swelling and pressure pain in the joints, and normal activity. There was no edema in both lower limbs. Physiological reflexes were normal and pathological reflexes were not elicited.
Specialized condition: the right maxillofacial bulge was obvious, the surface skin color was normal, and the skin temperature was not high. The ascending branch of the right mandible was deformed towards the body of the left mandible, the buccal side was obvious, the surface skin was not red, no rupture, the boundary of the swelling was unclear, inactive, hard, no ping-pong-like sensation, no pressure pain. The cheek bulge was normal. There was no redness, swelling or pressure pain in the bilateral temporomandibular joint area, and the degree of mouth opening and mouth opening pattern were normal. The tongue mucosa was normal in color, without congestion or ulceration, and the tongue was freely extended. Bilateral parotid, submaxillary and sublingual glands had no redness or swelling, and there was clear salivary flow. The pharynx was not congested, the tonsils were not enlarged bilaterally, and the uvula was centered.
Laboratory and special examination
The whole-mouth surface tomogram showed (outside hospital): a large area of bone density reduction was seen in the right mandibular ascending branch towards the left mandibular body part, which was elevated laterally and showed hairy glass-like changes.
Preliminary diagnosis: mandibular bone fibrous anomalous proliferation disorder
The patient’s CT and three-dimensional reconstruction showed that the mandible was affected from the neck of the right mandibular condyle, down to the body, to the body of the left mandible, with buccolingual expansion and significant bone destruction. The Chinese Academy of Sciences was contacted to create a three-dimensional model using three-dimensional reconstruction data, and a simulated debridement was performed on the three-dimensional model and fixed using mandibular reconstruction plates. Osteotomy for mandibular osteofibrodysplasia anomalosa and fixation of mandibular reconstruction plate were scheduled on March 25, 2004 under general anesthesia.
Surgical procedure.
After successful general anesthesia, the patient was placed in a supine position with the head tilted to the healthy side and shoulder pads. The surgical field was routinely disinfected with 1:1000 thimerosal tincture and 75% alcohol, and sterile sheets and towels were laid.
A parallel incision of approximately 15.0 cm in length was made in the right submandibular region about 2.0 cm from the lower edge of the mandible forward around the subchin to the contralateral submandibular region, and the skin, subcutaneous tissue, broad cervical muscle and superficial layer of deep cervical fascia were incised, separated upward and bluntly to the surface of the mandible, and the periosteum was incised and separated subperiosteally, and most of the right mandibular ascending body and the left mandibular body were seen to be eroded. The patient’s family was shown the swelling and explained that there was a high possibility of recurrence of the swelling, and the swelling was locally scraped and sent to ice, which was reported as “abnormal proliferation of bone fibers”. The wound was rinsed repeatedly with saline to stop bleeding completely, a rubber drainage tube was placed, and the wound was closed in layers. The wound was covered with a sterile dressing and dressed with pressure. The excised specimen was sent for pathological examination. The operation was completed.
The operation went smoothly, the anesthesia effect was satisfactory, there was much intraoperative bleeding, about 1500 ml, 800 ml of blood was transfused, the condition was stable, and the patient returned to the ward. Postoperative primary care was given to prevent infection. Bilateral submaxillary and chin pressure bandages were applied, and the gastric tube was lowered. When the neck wound healed well, the drainage strip was removed and pressure bandaging was continued. The diet was changed to oral semi-fluid. Curved tomograms were taken. Recovery was smooth with grade A healing of the incision. No in-hospital infection or other complications occurred during the hospitalization.
Condition at discharge: good general condition, good incision healing (I/A), pathology return: mandibular bone fiber abnormal proliferation disease.
Discharge diagnosis: abnormal proliferation of mandibular bone fibers.
Post-discharge precautions: 1. pay attention to rest and nutrition. 2. pay attention to wound protection in the near future. 3. semi-liquid diet and soft diet after discharge, soft diet after one month, and general diet after 2-3 months. 4. regular re-examination.
II. Diagnostic and treatment thinking process.
Fibrous dysplasia (abnormal bone fiber proliferation) is a self-limiting benign bone fibrous tissue disease of unknown etiology and slow progression. The monoblastic type accounts for about 70%, the polyostotic type without endocrine disorder for about 30%, and the polyostotic type with endocrine disorder for about 3%. It may be related to trauma, infection, endocrine dysfunction or some causes of local blood circulation disorder, but none of them have been confirmed. It is generally accepted that this disease is not a true tumor.
Pathological changes, vascular supply variation is large, the lesion tissue is largely white, gray or pale yellow, slightly softer than normal bone tissue, there is a sense of sand or elasticity when cutting, huge bone damage mostly from the bone marrow outward erosion and expansion, the bone cortex of tubular bone and flat bone only leaves two thin shell, remove the shell as remove the envelope. Microscopically, the reticular bone trabeculae vary in size, shape, and distribution, and are irregularly embedded in loose or dense connective tissue rich in cells and blood vessels. This tissue resembles the result of connective tissue metaplasia. Bone trabeculae are highly variable in morphology, mostly spherical, curved, C-shaped or bowed in cross-section, with irregular margins and wide osteocyte lacunae. Bone trabeculae are closely spaced and form a bone network. Bone trabeculae are composed of coarse fibrous protosteum and appear reticulate rather than plate-like under polarized light microscopy. Occasionally, a plate-like deformation of the reticular bone is seen, and sometimes bowed trabeculae are seen surrounding a central vessel. Most trabeculae lack an outline of osteoblastic composition. This can be differentiated from ossifying fibromas [2-3].
Most authors agree with the classification proposed by Beleval and Schneider (1954), which divides the disease into three types: (i) monobony type: single or multiple lesions involving a single bone, with the maxilla having the most incidence at 64%, the mandible at 36%, and the craniofacial bones at 10%. (ii) Multiple bone type without endocrine disorders: multiple lesions involving more than one bone. The incidence of craniofacial involvement is 5% in the polyosteotype with moderate skeletal involvement and 100% in the polyosteotype with extensive skeletal involvement. van Tilburg, after reviewing 144 patients reported in the literature, found that the frontal and pterygoid bones were most frequently involved in the monostyle and polyostyle, followed by the sieve and temporal bones. It can develop unilaterally or bilaterally at the same time. (3) Multiple bone type with endocrine disorder: the ratio of this type to single bone type is 30:1. The damage is spread over multiple bones, often unilaterally, and is accompanied by large skin pigmentation spots. It is mostly seen in females and shows premature secondary sexual characteristics [4-7].
The disease occurs in about 60% of cases before the age of 20 years, occasionally in infants and older adults over 70 years. More than 80% of men and women show deformed swelling of the bony area, with asymmetry on both sides of the face, displacement and protrusion of the eyeballs, narrowing of the nasal cavity, loosening of the teeth, malformation of the alveolar ridge, lacrimation, and elevation of the palate. Headache and occasional epistaxis may occur as the lesion progresses. Depending on the primary site and the extent of involvement, the clinical symptoms may be manifested accordingly. If the lesion occurs in the temporal bone, it often shows volume expansion and deformation of the temporal bone, narrowing of the external auditory canal, and conductive deafness. About 16% of those with external auditory canal stenosis have cholesteatoma as a complication. In cases with cholesteatoma, it often leads to temporomandibular arthritis, facial palsy, labyrinthitis or intracranial complications, and lesions involving the cochlea and internal auditory canal may produce sensorineural deafness. Invasion of the rock bones predisposes to symptoms of involvement of the middle or posterior cranial fossa. The disease can extensively invade the sinuses, orbits and the base of the anterior cranial fossa, and has a tendency to grow malignantly clinically, manifesting as nasal congestion, hyposmia, facial asymmetry, protrusion and displacement of the eyes, diplopia, visual impairment and difficulty in opening the mouth. There is abnormal proliferation of bone fibers in the pterygoid bone and pterygoid sinus area, mostly with more severe frontoparietal or occipital pain. Due to the thin wall of the pterygoid sinus, the lesion can easily extend to the surrounding structures and involve the cranial nerves such as II, III, IV, V and VI to produce symptoms and signs of cranial nerve damage. Larger lesions may lead to cerebral atrophy or hypercranial hypertension [8-11].
Except for the monoblastic type, which is not easily detected at an early stage, the diagnosis is usually confirmed without histological evidence by combining history, location, physical signs and imaging. The radiological diagnosis is usually not difficult, but only some of the lesions are similar to other diseases, which may lead to misdiagnosis.
Differential diagnosis [11-14]
1. ossifying fibroma In recent years, it has become clear that this disease and osteochondrodysplasia are two completely different diseases. The former is a slow-growing, isolated lesion that affects the mandible more than the maxilla, and occasionally the frontal bone and sieve bone. It is more frequent in females than males and occurs between 15 and 26 years of age. X-rays show a well-defined and inflated transparent appearance with a patchy or opaque central portion. Microscopically, the fibrous component of fibrous bone is predominant, and irregular bone trabeculae are haphazardly distributed in the fibrous matrix and form the center of the reticular bone, but there are osteoblasts at the periphery of the lamellar bone with the occlusal margin.
Eosinophilic granuloma is a benign isolated non-neoplastic osteolytic damage originating from the reticuloendothelial system. It is commonly found in the frontal, parietal and mandibular bones. It occurs mostly before the age of 30 years, with a male predominance. Histologically, it consists of dense foamy histiocytes accompanied by varying numbers of eosinophilic erythrocytes and multinucleated giant cells. The histiocyte nuclei contain small vesicles, the eosinophils contain tiny vacuoles, and the giant cells are of the Langham and foreign body types. These cells are focally clustered.
Gardner syndrome This syndrome is a multiple osteoma invading the maxilla and mandible, skull and occasionally the long bones, with intestinal polyps, dermatomal cysts, fibromas and focal corrugated bone cortical thickening of the long bones.
4. Giant dental osteoma usually involves all of the mandible and may result in cortical enlargement, which appears as a dense mass on x-ray. It often has a genetic origin and no histological source of infection is found.
5. Exophytic osteoma Paranasal sinus malignant tumor and cyst should be distinguished to prevent misdiagnosis.
6. Abnormal proliferation of multiple bone fibers should also be differentiated from hyperthyroidism, paget’s disease, neurofibromatosis and jaw hypertrophy.
7. Enamel cell tumor: It occurs mostly in young adults, and is common in the body of the mandible and the angle of the mandible. The growth is slow and there is no conscious symptom at the beginning; the gradual development can make the jaw bone expand and cause deformity and left and right facial asymmetry. When the tumor invades the alveolar bone, the teeth can be loosened, displaced or lost; when the tumor continues to grow, the outer plate of the jaw bone can be thinned or even absorbed, and then the tumor can invade into the soft tissue. Due to the invasion of tumor, it can cause chewing, swallowing, breathing difficulty, neurological symptoms, pathological fracture, misalignment of bite and eye and nose symptoms. Radiographic manifestation: early stage is beehive-like, and later forms multi-room cyst-like shadow, single room is less. The wall of the cyst is not neatly edged and has a semilunar cut. There may be irregular resorption of the root tip within the capsule. Brownish fluid may be extracted by puncture.
8. Keratotic cysts: Most commonly found in young people aged 20-30 years old in the molar region of the mandible and ascending branches. Generally no conscious symptoms, slow growth. Swelling growth, single room is often seen along the long axis of growth. There are multiple, genetic characteristics. It may also contain teeth. Puncture can extract milky white or yellow fatty material.
9. Bone cysts: slow growth, no initial conscious symptoms. After development, the bone can be resorbed and thinned. Puncture is straw-yellow cystic fluid with yellowish-white keratin-like material. If it contains teeth, it is a tooth-containing cyst.
10. Endogenous chondrosarcoma: Mostly seen in small bones of hands and feet. If this disease involves the long bone stem, it may show multifocal hypodense areas, but irregular calcification is common within the lesion.
11. Chronic osteomyelitis: In some patients with chronic osteomyelitis, the thickening of the bone cortex is not obvious and is manifested as an enlarged and thickened backbone, similar to the abnormal proliferation of bone fibers. However, patients with osteomyelitis have collapsed bone trabeculae in the bone marrow cavity without clear bone structure or have dense sclerotic foci that fuse with surrounding bone structures.
12. Non-ossifying fibroma: The CT presentation is similar to that of osteochondrodysplasia, but the hypodense zone of the former is not frosted glassy, and it is often a single lesion.
13. Giant cell tumor of bone: It is often a solitary lesion, mostly seen in the lower femur, upper tibia and distal radius. The lesion appears as a hypodense area with swollen compartments, thinning of the bone cortex, and generally no periosteal reaction.
Ancillary examinations [15-19].
The imaging examination has special significance for the diagnosis of this disease. According to the radiographic manifestations, the disease is divided into three types: ① deformational osteitis type: it is often manifested as a multiple bone type lesion, which is characterized by cranial thickening, unilateral vesicular expansion of the outer plate and parietal bone of the skull, expansion of the inner plate into the plate barrier and cranial cavity, coexistence of limited and diffuse ray-transparent and dense areas in the thickened skull, and the coexistence of this bone resorption and sclerosis is very similar to the manifestation of Paget’s deformational osteitis. Cranial enlargement and sclerosis may extend from the frontal bone to the occipital bone. Facial involvement may lead to narrowing of the orbital and nasal cavities and loss of the sinus cavities, accounting for about 56% of this type. ②Sclerotic type: This type is mostly seen with maxillary hypertrophy, which can lead to misalignment of teeth and small nasal and sinus cavities under pressure. The maxilla is more involved than the mandible, and it is mostly a single bone type. The damage has a sclerotic or hairy glass-like appearance. Conversely, mandibular damage is more often seen in the multi-bone type, showing isolated bone walls that are smooth and ray-permeable. This type accounts for approximately 23% of cases. (iii) Cystic type: The skull shows isolated or multiple annular or rosette-shaped defects, which start from a thin sclerotic rim and can be several centimeters in diameter. Isolated lesions have the appearance of eosinophilic granulomas, multiple defects can be mistaken for Hand Schüller Christian disease, and occasionally several x-ray types appear on the same body. This type accounts for approximately 21% of cases. The application of CT or MRI can clarify the location and extent of the lesion and show the association with soft tissue. Regular examination can dynamically observe the degree of lesion development, which is very important for selecting the surgical approach, reducing complications and estimating the prognosis.
III. Exploration of individualized treatment.
Abnormal bone fiber proliferation was first discovered by Well (1922), and its main pathological change is the replacement of normal bone tissue by fibrous tissue. The disease, especially the monoblastic type, is mainly treated by surgical resection, because radiotherapy may induce malignant changes.
In view of the slow clinical progression of the disease, for small or asymptomatic lesions, surgery may be suspended, but close follow-up should be observed. For those with rapid lesion development, with obvious deformity and functional disorders, surgery should be considered as an indication. Although radical excision is the best treatment, it has the disadvantage of leading to functional disorders and cosmetic defects. Conservative partial excision is prone to recurrence, which is 21% for the single-bone type and up to 36% for the multiple-bone type. Therefore, the surgical method and approach selection should be flexible according to the primary site, the scope of invasion and the degree of functional impairment, in principle, to remove the lesion tissue as completely as possible, but also to preserve the maximum physiological function of the organ and cosmetic effect, and to design and implement individual treatment plans for patients. For children and those with extensive lesions, general anesthesia through the oral cannula is recommended. Those with limited lesions can also be removed under local anesthesia [21, 22].
There are various surgical incisions that can be applied depending on the lesion.
(i) Caldwell-Luc method: for lesions with extensive involvement of the maxilla, nasal cavity, infraorbital wall, septal sinus and pterygoid sinus.
② Weber-Fergusson method: applied to patients with extensive involvement of the maxilla, infraorbital wall, zygomatic bone, hard palate and pterygoid septal sinus.
③ Combined craniofacial approach: including double frontal flap or single frontal flap + Weber-Fergusson incision, for extensive lesions originating from the base of the anterior cranial fossa or from the sinus and orbital wall with reciprocal invasion.
④ Fish method: for lesions originating in the temporal bone, external auditory canal, middle ear, inner ear, rock bone and cranial middle fossa floor involvement.
Surgery with flat chisel, round chisel or large scraping spoon is preferred for resection in stages. The traumatic surface has a lot of blood leakage, and it is advisable to use bone wax to stop the bleeding and give the necessary blood transfusion, especially in children. The prognosis for surgical resection of this disease is good, so do not over resect the important nerve and blood vessel lesions adjacent to the skull base and intracranial area during surgery to avoid accidents.
Computer-aided design and computer-aided manufacturing (CAD/CAM) are becoming more and more popular in today’s applications, and CT three-dimensional reconstruction is now basically equipped in primary hospitals. With the advancement of science and technology, the 3D measurement technology of human body has made great development. Using the 3D reconstruction technology to collect the digital model of the patient’s maxillofacial area, and using the inverse engineering and CAD/CAM technology, an accurate solid model can be obtained. The use of solid models can achieve precise debridement, which can avoid the possibility of secondary surgery caused by insufficient surgical scope, and prevent over-treatment so that patients receive unnecessary losses. Such a surgical model, which can be applied not only to the abnormal value-added bone fibers, but also to the fields of jaw deformity, orthognathic surgery and aesthetic plastic surgery in the future, is a surgical model worth promoting and is the ultimate trend of future surgical development.
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