Introduction
Osteomas are benign, slow-growing tumors that arise most frequently in the craniomaxillofacial region.1 One study reported that the frontal bone was the most common site of presentation of peripheral osteomas, followed by the mandible and maxilla.2 Histopathologically, osteomas are characterized by 3 subtypes, as compact or ivory (composed of normal dense bone and scattered bone marrow spaces), cancellous (predominated by trabeculated bone and abundant fibroadipose marrow) and a mixed pattern (showing both histological features).3 Osteomas may be asymptomatic for a long time until they cause deformation of the bone or compress adjacent structures.1 The clinical signs depend on the size and location of the tumor, as well as the direction of its growth. Morphologically, they are similar to common osseous tissue. They are classified as central, peripheral, or extra skeletal. Central osteomas develop from the endosteum. Peripheral osteomas arise from the periosteum, and extra skeletal soft tissue osteomas grow within a muscle.4 The incidence of osteoma of the frontal bone and frontal sinus ranges from 37-80% in the reported cases. But isolated cases of osteoma of the forehead, without involvement of the sinus, are rare.5 There are numerous options available for surgical removal of a forehead osteoma. The endoscopic approach for treating forehead osteomas is less invasive and facilitates complete removal of tumors, which results in good cosmetic outcomes.6 The anterior hairline approach with subcutaneous dissection is an effective method for removal of forehead osteoma since it offers broad visualization and hides the scar in the hairline. In addition, the dissection in the subcutaneous plane avoids inadvertent injury to the deep nerve branches and helps to maintain scalp sensation.7 In our article, we present the case of forehead osteoma removed by bicoronal (bitemporal) incision in the scalp. It was used because it is hidden, has the most aesthetic outcomes, and it offers broad visualization. The goal was to completely remove the tumor to prevent recurrence and to restore the resulting cavity.
Case Report
A 44-year-old woman had a bone tumor in the forehead bone on the left side, noticed 23 years ago. It is round and raised on the bone, not painful, but aesthetically annoying. The surgical goal was to restore the normal appearance of the patient's face and to exclude any possibility of recurrence in the future. After conducting a clinical examination, palpation, and taking a medical history, the patient was sent to make a computed tomography (CT) scan of the head (Figure 1 A-D). In radiological study, the tumor was seen and measured, a base diameter of 23.1 mm and a height of 6.44 mm (Figure 1 D), it arises from the outer side of the cortical layers of the frontal bone on the left side, no swelling, no compression on the brain. Compared with a patient's CT scan of 2014, we observe the same dimensions, without negative dynamics. The patient was informed about the risks of the surgical procedure, the possibility of entering the cerebral system, and the potential complications of meningitis and cerebrospinal fluid leakage. All pre-operative procedures, including tests and examinations, were carried out. The surgery was performed under general anesthesia with nitrous oxide gas and oral intubation. A complete coronal incision was made, and the layers of skin were dissected from the incision to the front, reaching the area of the bone tumor. The area of the bone tumor was completely exposed (Figure 2 A). The bone tumor was removed using piezosurgery (Figure 1 B), a hammer, and a chisel (Figure 2 C). The bone tumor was completely removed up to the inner bony cortex of the frontal bone, and the dura mater in the center of the cavity was exposed approximately 4 mm (Figure 2 D). The cavity resulting from the removal of the bone tumor was restored using radiopaque bone cement polymethyl methacrylate (PMMA) which is usually used to fix pathological fractures of the vertebral body (Figure 3 A). PMMA is generally considered to be a safe and non-toxic material. On October 14, 1999, FDA issued an order reclassifying the polymethylmethacrylate (PMMA) bone cement from class III (premarket approval) into class II (special controls). The used bone cement consists of a sterile liquid and a powder. The liquid component which is a colorless liquid monomer (Methyl methacrylate, N, N-dimethylparatoluidine, Hydroquinone) and the powder component (Polymethylmethacrylate " including Benzoyl Peroxide", Barium Sulfate) was mixed forming a polymer form that resembles a thick, viscous mass. The bone was restored with this mass and was shaped to give a symmetrical and nearly correct anatomical shape. Working time was approximately 10 minutes, set time of 10.2 minutes at 37ºC. The bone cement waited to harden, and then the formed surface was modified and smoothed by physio dispenser to obtain symmetry on both sides of the forehead and correct anatomical shape (Figure 3 B, C). After this procedure, and at the patient’s request, a cosmetic midface lift was performed by extending the incision on both sides to the area just in front of the ears. Then sutures and surgical staples were placed in the scalp area. The incisions in front of the ear were sutured with subcuticular stitches. During the surgical procedure, the surgical flap was flipped back to its place every ten minutes and moistened with saline solution to ensure blood supply and prevent the flap necrosis. During the surgery, corticosteroid and antibiotics were infused intravenously.
The first day after the operation, the patient is in good condition, no fever, no immune reaction at the place of the bone cement and around it, there is no inflammation, the face is symmetrical and the forehead is symmetrical, generalized edema in the face. The patient is wearing a postoperative headband. On the fifth day of surgery, the patient is in good and stable condition, absence of facial edema by 85%. The patient gave an interview on YouTube to tell her story about the bone tumor. Histology report: Fragments of dense compact lamellar bone tissue, cortical type with small rounded Haversian canals, without signs of atypia, a few small osteocytes - a picture of osteoma. In computed tomography there is no immune reaction, there is no intracranial or extracranial bleeding or leakage (Figure 4). On the fourteenth day, the patient is in stable condition, absence of edema, the surgical staples were removed under intravenous sedation. The patient was informed of the necessary follow-up examinations in a month, three months, six months, and a year.
Table 1
Glossary
Figure 1
Radiological evaluation of the tumor. (A): 3D CT soft tissue surface. (B): 3D CT skull surface. (C): CT Coronal section showing the tumor. (D): CT horizontal section showing tumor measurements
Figure 2
Pictures from the surgical procedure. (A): Elevation of the coronal flap and exposure of the tumor. (B): Drilling the tumor boundaries using piezosurgery. (C): Using surgical hammer and chisel. (D): Cavity resulting
Discussion
In this case, we had several surgical options, each of them has pros and cons. The option of removing the tumor by endoscopy does not give the ability to completely remove it, which may lead to recurrence in the future. To prevent recurrence, it is essential to conduct additional meticulous burring and a thorough inspection of the surface after copious irrigation.8 Removing the tumor without restoring the area would lead to an unaesthetic appearance of a hollow in the forehead. Reconstruction with bone graft products will be lost, these products have poor stability in open places, especially in an area with strong muscle tension and movement. Reconstruction with autograft or allograft requires stabilization with screws, then a second operation to remove them. However, it is difficult to shape it into the resulting cavity. In reconstruction using metal plates with or without bone graft, the patient will undergo a second surgery to remove the plate, in addition to the uncomfortable feeling that the patient may experience due to the thin skin over the plate. Therefore, restoration using bone cement was chosen, noting that the recent results are not clear. But according to studies it can turn into cartilage tissue and then bone tissue. During 58 months of follow-up, the average VAS was 1.8, and no postoperative complications occurred during the follow-up period.9
Conclusion
There have not been sufficient studies to prove the effectiveness of the PMMA cement in bone especially in areas which are not subject to mechanical stress, that’s why further investigations are necessary. However, our results are optimistic. In the future, if it is fully studied, it will be a solution to many problems within certain parameters.
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