INTRODUCTION
Most osteomas can be removed by incising the overlying skin along the relaxed skin tension line and excising the exposed tumor. However, this conventional approach is inappropriate for those osteomas located in a conspicuous location. For this reason, forehead osteomas are removed via the bicoronal approach with subgaleal dissection or endoscopic surgery. Endoscopic surgery is minimally invasive but cannot be used for removal of large masses. The bicoronal approach offers broad visualization and hides the incisional scar behind the hairline but may expose the deep branch of supraorbital nerve to injury [1,2]. In this ideas paper, we present three cases of frontal osteomas removed via an anterior hairline approach with subcutaneous plane of dissection.
IDEA
Between May 2014 and February 2015, we removed forehead osteomas from three female patients (30, 42, and 60 years old) between May 2014 and February 2015. These masses had been growing for 3 to 15 years (Table 1). None of the patients had ever been exposed to trauma, nor did they have associated symptoms such as headache, tenderness, and hypoesthesia. Each patient had presented to the hospital with the chief complaint being palpable mass. The size and location of osteomas were confirmed by preoperative computed tomography (CT) scan (Fig. 1). Each patient wished to have the respective tumor removed without leaving a prominent forehead scar, and thus the option of anterior hairline approach was offered and accepted.
Operative technique
Upon general anesthesia, a 1% lidocaine with 1:100,000 epinephrine mixture was injected into the anterior hairline incision site. This tumescent injection was extended into the forehead for hemostasis and hydrodissection. The incision was designed along the anterior hairline to temporal crests on both sides (Fig. 2). The incision was performed in the orientation of hair follicles, using a No. 15 blade. After incision was extended down to the subcutaneous fat layer, the dissection was carried in this plane towards the site of osteoma. With the dissection completed, the frontalis muscle and periosteum were incised parallel to the course of supraorbital nerve (Fig. 3). The exposed osteomas were freed with a burr drill and removed using an osteotome. The resultant bony defect was re-contoured using a Medpor®. Drains were not placed. Upon adequate hemostasis, the subcutaneous fat layer was closed with 4-0 PDS sutures. Gauze and bandage were used as compressive dressing. The surgical staples were removed on the 7th day after surgery.
DISCUSSION
Benign tumors commonly found on the forehead include lipoma, dermoid cyst, epidermal cyst, and osteoma [1]. Among these, osteomas occur with frequency in the skull vault and facial skeleton [3]. The frontal sinus is the most frequent location of cranial osteomas [4]. Osteomas are known to keep growing and metastasize to nearby tissue. In general, patients most frequently present with this bony lesion in the third and fourth decade of life, and male are affected somewhat more frequently.
In the absence of symptoms, there is no need to remove osteomas by surgery. However, it is necessary to remove osteomas to preserve major organs and for aesthetic purposes. Also, frontal osteomas are indicated for resection if accompanied by symptoms, block frontal sinus drainage, account for more than 50% of the frontal sinus volume, when continued growth is evident in X-ray examinations, or if the growth affects the sphenoidal sinus [5]. In our three patients, surgical resection was offered because of the aesthetics and also because of the history of continued growth.
Although direct skin incisions are appropriate for small tumors, the coronal approach or endoscopic surgery is commonly used when the tumors are large and conspicuous scars are unacceptable. Endoscopic surgery has the advantage of leaving a small scar, but is associated with increased risk of damage to facial or sensory nerves. This minimally-invasive approach is not appropriate for incising large tumors [2,6]. The bicoronal incision is useful for accessing the upper and middle facial bones, including the zygomatic arch. This approach provides excellent visualization of the surgical site and allows the incisional scar to be hidden behind the hairline. In addition, extension of the incision down to the preauricular area allows exposure of the entire orbit [7]. However, this extended approach can lead to injury of the temporal branch of the facial nerve, if the operator is not experienced in distinguishing between the superficial and deep layers of the deep temporal fascia. Bicoronal approach may cause temporary dysesthesia of posterior incision, temporary hair loss at the incision site, and complications that include injury to the temporal branch of the facial nerve when extending the incision to the front of tragus [8].
The supraorbital nerve exits the frontal bone through the supraorbital foramen before dividing into two branches. The superficial branch of the supraorbital nerve courses over the surface of frontalis muscle to provide sensation to the central forehead. The rest of the scalp and top of the head are innervated by the deep branch, which travels laterally between the periosteum and galea. The deep branch runs in a 1 cm-wide band medial to the palpable temporal crest line and innervates the frontoparietal scalp [9]. Because of this anatomy, subgaleal dissection may cause permanent forehead numbness or hypoesthesia [1]. In order to prevent this potential complication of the subgaleal dissection, we removed forehead osteomas through an anterior hairline incision and subcutaneous plane of dissection. During follow-up periods ranging from 6 to 12 months, no complications were noted, such as facial nerve paralysis, forehead hypoesthesia, infection, and hematoma. This procedure provides a couple of advantages for avoiding scar formation. First, the anterior hairline approach requires incision line shorter than that of the conventional bicoronal approach. Second, the incision line is not straight but curved. Hence, the scar is less visible due to camouflage effect.
Despite the small number of cases, our experience with the anterior hairline incision and subcutaneous dissection has been encouraging. The method allowed us to remove relatively large osteomas without injury to the nerve branches that traverse the forehead tissue. Aesthetic outcomes were excellent. This method provides access to a wide sections of the forehead through a relatively small incision because the elevated flap by subcutaneous dissection is more thin and pliable than the conventional method.
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