Surgical Recontouring of Craniofacial Fibrous Dysplasia Using Stereolithographic Models

Introduction

The term “fibrous dysplasia” was first introduced by Lichtenstein in 1938.¹ It is a benign fibroosseous disease in which normal bone marrow is replaced by abnormal fibrous connective tissue.^2,3 Fibrous dysplasia is further classified into three subtypes: monostotic, polyostotic and craniofacial. Lesions confined to contiguous bones in the craniofacial region are referred to as craniofacial fibrous dysplasia.⁴ The condition typically presents in the first and second decade of life, is often asymptomatic, and progresses slowly. Depending on the type and location, it may cause facial deformity or asymmetry, auditory impairment, nasal congestion, visual disturbances, pain or tenderness, nasal obstruction, paresthesia, or malocclusion.⁵ Cosmetic recontouring is the treatment of choice, however more aggressive treatments are indicated if the lesion is large.^2,6 Stereolithographic models, three-dimensional surgical guides created by mirroring the unaffected side, are valuable for accurate surgical planning. They allow precise estimation of bone reduction, minimize intraoperative time, and enhance the accuracy of reproducing the virtual surgical plan.² Here we report a case of craniofacial fibrous dysplasia involving the lateral one-third of right supraorbital region treated surgically through recontouring with the help of a stereolithographic model.

Case Report

A 20-year-old male presented to our department with a chief complaint of swelling in the right lateral region of the forehead, present for the past eight years. The patient reported a history of trauma to the area after being struck by a stone eight years ago, following which he noticed a small swelling approximately the size of a peanut.The swelling gradually increased in size over the years, reaching its current size about two years ago, and has remained stable since then.

On gross facial examination, a solitary bony swelling was observed on the lateral one-third of the right supra­orbital region, measuring approximately 5 × 5 × 5 cm at its greatest dimensions. The lesion was roughly oval in shape, with the overlying and surrounding skin appear­ing normal in color. On palpation, the inspection find­ings were confirmed, the swelling was non-tender, bony hard, immobile, and well-defined, with no localized rise in temperature. No other abnormalities were detected on systemic examination (Figure 1).

A 3D CT scan revealed an expansile bony lesion measuring approximately 4 × 4.8 × 4.8 cm, involving the right orbital portion of the frontal bone. The lesion extended inferiorly to the upper part of the lateral orbital margin and the roof of the right orbit, and posteriorly up to the orbital apex, resulting in a reduction of intraorbital volume. It demonstrated expansion of both the outer and inner cortices with a ground-glass density matrix, and the lesion margins showed a narrow zone of transition (Figure 1).

The lesion was provisionally diagnosed as craniofacial fibrous dysplasia and was treated by surgical recontouring under general anaesthesia. A bicoronal incision was made to raise a flap and expose the bony lesion (Figure 2). Using a micromotor handpiece, checkerboard pattern markings were created on the swelling, followed by careful removal of each section with a chisel and mallet. A template fabricated from the mirrored image stereolithographic model was periodically adapted to the affected side to guide bone reduction and ensure bilateral symmetry. Bone trimming was performed with a diamond bur until the template fit precisely onto the bone surface. A surgical drain was placed, and layer wise closure was done using 3-0 Vicryl and 3-0 Ethilon sutures. Postoperative follow-up for six months showed satisfactory healing with no evidence of recurrence.

The H&E-stained decalcified sections revealed broad, irregularly shaped trabeculae of cellular osteoid and mature lamellar bone embedded within a loosely arranged, moderately cellular fibrous stroma. Some trabeculae exhibited osteoblastic rimming and areas of peritrabecular clefting, consistent with the histopathological features of fibrous dysplasia.

Discussion

Fibrous dysplasia is a benign developmental hamartomatous condition characterized by the replacement of normal bone architecture with abnormal fibrous connective tissue interspersed with irregular bony trabeculae.⁷ The condition was first described by Lichtenstein in 1938 and later, in 1942, Lichtenstein and Jaffe provided a more detailed account of the disorder.⁸

Currently, fibrous dysplasia is classified based on the number of bones involved: monostotic, when a single bone is affected, and polyostotic, when multiple bones are involved. Monostotic fibrous dysplasia is more com­mon, typically occurring in the second and third decades of life, and accounts for approximately 70-80% of all cases.^9,10

Eversole et al., classified the craniofacial type of fibrous dysplasia as a polyostotic variant, since multiple bones of the craniofacial skeleton are affected, separated only by sutures. The polyostotic form is further divided into three subtypes: (1) Craniofacial FD, in which only craniofacial bones are affected (2) Lichtenstein-Jaffe type characterized by involvement of multiple skeletal bones, café-au-lait spots, and occasional endocrinopathies; and (3) Albright's syndrome, which is a triad of mostly unilateral polyostotic FD, café au lait skin pigmentations & endocrinopathies.¹¹ An additional, uncommon variant is Mazabraud syndrome, in which fibrous dysplasia is associated with soft-tissue myxomas.

Since their introduction by Charles Hull in 1986, stereolithographs (three-dimensional models) have been utilized in craniofacial surgery for various applications.¹² Over time, 3D printing technology has become an integral tool in cranio-maxillofacial surgery, aiding in procedures such as distraction osteogenesis, orthognathic surgery, and the management of cranio-maxillofacial deformities and jaw-related pathologies.¹³

Even before treatment begins, 3D printing 3D printing enables surgeons to visualize the surgical plan and anticipate potential challenges. This technology allows for the rapid creation of highly accurate anatomical replicas with minimal deviation from the original structure, thereby enhancing postoperative outcomes and reducing surgical time.¹³ In maxillofacial surgery, models made of acrylic, epoxy resin, or 3D-printed materials are most commonly used. The fabrication of stereolithographic (SLA) models involves specialized software that integrates data from computed tomography (CT) scans to produce a precise resin replica. Each slice of the CT axial image corresponds to a sequential layer in the 3D-printed model, ensuring anatomical accuracy.¹⁴

The primary goal of treatment should be to optimize function, while also preventing complications and improving facial aesthetics. Surgical options range from conservative approaches such as curettage, bone remodeling, or contouring to aggressive interventions like complete resection followed by immediate reconstruction. Subsequently a classification based approach for managing craniofacial fibrous dysplasia (FD), dividing the skull into four anatomical zones was proposed. Zone 1: Includes the frontal, nasal, orbital, zygomatic, ethmoid, and upper maxillary bones. As this region forms the most visible part of the facial skeleton, complete excision and reconstruction are recommended. Zone 2: Comprises the lateral cranial base, temporal bone, parietal bone, and part of the occipital bone. Since this area is covered by hair, either conservative or radical resection may be performed. Zone 3: Consists of the petrous, mastoid, pterygoid, sphenoid, and central cranial base bones. This is considered the most complex and high-risk zone; therefore, conservative management is advised for asymptomatic patients. Zone 4: Divided into 4a (maxillary alveolar bone) and 4b (mandible). Conservative excision and recontouring are recommended in this region.¹⁵

Conclusion

The management of craniofacial fibrous dysplasia poses a challenge to surgeon due to its functional and esthet­ic implications. Stereolithographic models generated from 3D CT scans serve as valuable tools for precise treatment planning and for creating surgical stents that enhance clinical outcomes. The use of this technology allows for accurate recontouring while maintaining fa­cial aesthetic harmony, effectively addressing one of the major challenges in surgical management.

Conflict of Interest

Nil