Periosteal reaction as a crucial radiographic finding for desmoplastic fibroma of the jaw bone in children: A case report

The ethical approval number of this case report is IR.GUMS.REC.1400.508. A 5-year-old boy with a tender and hard bony swelling on the right side of the mandible body that had lasted for 3 months was referred to the Department of Maxillofacial Surgery of Guilan University of Medical Sciences by a dentist. The patient had gross swelling in the right side of the mandible and a history of extraction of the second primary molar, but without improvement. There was no history of systemic disease, fever, trismus, or odynophagia. The first panoramic radiograph showed fine spicules arising from the inferior border of the mandible on the right side, in the first premolar and molar regions (Fig. 1). Unfortunately, the dentist missed this abnormal finding on the panoramic radiograph.

Fig. 1
A. Extraoral photograph shows swelling of the right side of the mandible. B. Intraoral photograph shows normal overlying mucosa. C. Panoramic radiograph reveals fine spicules on the inferior portion of the mandible in the right first premolar and first molar areas (white arrows).

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Despite using clindamycin, ceftriaxone, and metronidazole, the swelling persisted. Ultrasonography of the region showed a hypoechoic solid mass with lobulated margins and dimensions of 32 mm×26 mm×20 mm with slight vascularity that had destroyed the mandibular cortex. There was no abnormality in the right submandibular gland or cervical lymph nodes (Fig. 2).

Fig. 2
Ultrasonography of the region reveals a hypoechoic solid mass with lobulated margins and dimensions of 32 mm×26 mm×20 mm, accompanied by destruction of the mandibular cortex.

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The first CBCT scan was taken 3 months after the first panoramic radiograph. Axial, coronal, and cross-sectional CBCT views revealed a lytic lesion on the lingual side of the right mandibular body with destruction of the lingual cortex, extending from the deciduous first molar to the permanent first molar. Nevertheless, in axial views, bony spicules in the lingual cortex near the inferior border of the mandible, as indicators of a periosteal reaction, were detected from the midline to the first molar area (Fig. 3). Desmoplastic fibroma, eosinophilic granuloma, Ewing sarcoma, osteosarcoma, and lymphoma constituted the first radiographic differential diagnosis list even though the histopathological report of the incisional biopsy was fibrous dysplasia. The results of the histopathological report were not convincing; therefore, the patient was followed for a few months.

Fig. 3
Axial (A) and coronal (B) cone-beam computed tomographic images show the destruction of the lingual aspect of the right side of the mandible and periosteal reaction near the inferior border (white arrows).

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The second CBCT scan was taken 3 months after the first biopsy, which demonstrated greater extension of the lesion (Fig. 4). Unfortunately, the patient’s parents refused surgical treatment. After 2 months and more exacerbation of the swelling, his parents accepted the second biopsy. The biopsy showed pieces of neoplastic tissue composed of sheets of proliferated, almost monotonous spindle cells was mild cellularity. Significant mitotic activity or tissue necrosis were not detected. A bundle of skeletal, muscular tissue was focally present at the periphery of the lesion surrounded by proliferated spindle cells, and immunohistochemical tests for vimentin and β-catenin were positive (Fig. 5). According to the histological and immunohistochemical features, the lesion was reported as benign locally aggressive spindle cell neoplasm with a differential diagnosis of desmoplastic fibroma (of bone with extra-mandibular soft tissue extension), fibromatosis (of soft tissue with secondary extension into the mandibular bone), and myofibromatosis.

Fig. 4
Axial (A) and coronal (B) cone-beam computed tomographic images 3 months after the first biopsy show progressive bone destruction and periosteal reaction (white arrows).

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Fig. 5
A. A histopathological examination reveals spindle cell proliferation arranged in streaming fascicles, which are associated with a variable amount of collagen and partial myxoid changes. In addition, immunohistochemical tests show positive findings for vimentin (B), and β-catenin (C).

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The third set of CBCT images and panoramic radiography, taken 2 months after the second CBCT scan and the personal decision of his parents for total surgical resection of mandible, showed marked progression of bone destruction and discrete new bone formation in the lingual and labial cortical plates, as well as the inferior border of the mandible, which represented a sunburst and layering form of periosteal reactions (Fig. 6). The lesion crossed the midline, and it was apparent in axial views at the level of the inferior third of the mandible and the lingual side.

Fig. 6
A. Axial and coronal cone-beam computed tomographic images after 5 months reveal vast destruction of the inferior, lingual, and buccal cortices, periosteal reaction and root resorption of the right mandibular first molar, and displacement of the developing first and second premolars. The lesion also crosses the midline. B. Panoramic radiograph shows destruction on the right side of the mandible and root resorption of the right first molar.

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After giving the information about the growth pattern of the lesion to the patient’s parents, the treatment plan (e.g., initial reconstructive surgery) and the need for future dental rehabilitation, close follow-up, and a delayed second operation with an autogenous bone graft were explained to them in order to obtain their permission.

Eventually, surgical resection of the mandible with a wide margin was performed, with simultaneous reconstruction using a surgical plate (Fig. 7A). The patient was included in a close follow-up plan because of the high recurrence rate. Based on the clinical, radiological, and histopathological examinations, the final result was desmoplastic fibroma of the mandibular bone. Fourteen months after surgery, follow-up panoramic radiography revealed a safe and intact margin along the surgical site, without recurrent lesions (Fig. 7B).

Fig. 7
A. Postoperative panoramic radiograph reveals the resection of the mandible with a wide margin. B. Follow-up panoramic radiograph after 14 months does not show a recurrent lesion.

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The radiological features of desmoplastic fibroma are nonspecific and variable. Desmoplastic fibroma can present as a unilocular or multilocular radiolucency, with a well- or ill-defined margin, as a totally radiolucent or radiolucent-radiopaque lesion, and as an expansile tumor with cortical thinning or destruction. Occasionally, lesions with rapid expansion and subsequent cortical perforation imitate malignancies.10, 15 Rapid expansion and subsequent cortical perforation can also result in the initiation of new bone formation from an osteogenic layer of periosteum, producing a sunburst appearance.6, 9, 11 Similarly, in the present case, bony spicules as an indicator of a periosteal reaction arising from the cortical plates of the mandible were visible, and layering bone formation in the labial cortex was also seen. Since the periosteal reaction originates from the periosteum, it may present only as fine spicules on conventional radiography in the initial stages, as seen in the present case and also in the case reported by Dalili-Kajan et al.,11 Khatib and Pogrel.,15 Said-Al-Naief et al.,16 and Shi et al.17

Based on radiographic features, malignant lesions such as osteosarcoma, Ewing sarcoma, lymphoma, and eosinophilic granuloma were considered in the differential diagnosis list. Nonconcentric periodontal space widening, called the “Garrington sign,”5 is a common radiographic feature in the alveolar regions in malignant lesions, absent in the present case. Although sclerotic-appearing bone can be seen in extensive osteosarcomas, other malignant lesions are usually completely radiolucent without any internal structure. Furthermore, eosinophilic granuloma is a multiple and well-demarcated lesion involving the mid-root epicenter of the tooth. Therefore, its early clinical finding is tooth mobility. It can also appear as punched-out lesions. Although periosteal new bone formation is not typical in eosinophilic granuloma, it could be found in the other lesions.5 It usually appears in their final stage when extensive osteolytic changes occur. The critical point in the present case is periosteal reaction as a primary imaging finding that could be a pivotal point in the early detection of desmoplastic fibroma.

In a histological evaluation, desmoplastic fibroma is characterized by uniform-appearing fibroblast cells in a stroma containing various amounts of collagen fibers.3 The lack of a capsule and the infiltrative nature of the lesion are hallmarks of desmoplastic fibroma. Low-grade fibrosarcoma and low-grade intraosseous osteosarcoma are the most challenging differential diagnoses.3 Hypercellularity with a herringbone pattern and higher mitotic activity in fibrosarcoma can help to differentiate it from desmoplastic fibroma. In addition, low-grade osteosarcoma can be distinguished by osteoid formation.3 It is worth noting, in the first histopathological report, that fibrous dysplasia may be due to an inadequate depth of the biopsy specimen.

In addition, the immunohistochemical analysis could be helpful for a better diagnosis.8 The cells of mesenchymal origin have a variable response to vimentin.18 β-catenin is a cytoplasmic protein regulated by the APC gene, which is involved in tumorigenesis.19 First, β-catenin binds to E-cadherin, and this complex helps inhibit and suppress the invasion of tumor cells. Its second role is in regulating cell proliferation and maintaining the normal cellular architecture. An increase in β-catenin expression can activate oncogenes and lead to various neoplasms and cancers.20, 21 Desmoid-type fibromatoses and adenocarcinoma have positive results for β-catenin.20 Multiple cases of desmoplastic fibromas of the jaw bones have been reactive to β-catenin,22, 23, 24 while some have not been.12, 22, 25

The comparative immunohistochemical findings of desmoplastic fibroma, fibrous dysplasia, and low-grade fibrosarcoma reveal that desmoplastic fibroma is low for Ki-67, positive for vimentin and smooth muscle actin (SMA), variable for β-catenin, negative for S100 and MSA, whereas low-grade fibrosarcoma is high for Ki-67, positive for vimentin, p53, and reticulin, and negative for S100, keratin, and SMA. Meanwhile, fibrous dysplasia has none of these findings.9 In the present case, the lesion was positive for vimentin and β-catenin.

Various rates of recurrence have been reported, ranging from 17% to 67%, depending on the treatment method.6 Increased cellularity seems to be associated with an increased tendency for recurrence.12 Various treatment approaches have been suggested for desmoplastic fibroma, including enucleation, curettage, resection, radiotherapy, and chemotherapy.6 Radiotherapy, because of its adverse effects such as fibrosis, paresthesia, pathological fracture, higher bone graft failure rates, and induction of osteosarcoma, is not recommended.15 In most clinicians’ opinions, surgical resection of the lesion with a wide margin is the preferred method to prevent recurrence.6, 11 Regarding the high rate of recurrence, long-term follow-up is necessary. Although there are no specific guidelines for radiographic follow-up, most reports have recommended a radiographic follow-up for a minimum of 3 years.10

Simultaneous bone reconstruction seems to be essential for patients to return to function. This issue is also essential because most patients are of growing age, and delayed or improper reconstruction may result in craniofacial abnormalities and malocclusion, which could affect their quality of life.

Although the small size of facial structures, limited donor sites, growth procedures, and small vessels are challenging factors in the reconstruction of pediatric bony defects, healthy vessels and a superior ability to heal result in a high rate of successful treatment.26

Reconstruction of mandibular defects can begin immediately postoperatively, but it is logical to consider a time interval to ensure a lack of recurrence. Usually, as in the case presented herein, reconstruction plates are used for immediate reconstruction, after which a second operation with a delayed autogenous bone graft and subsequent dental rehabilitation are performed to restore function.27

In conclusion, the periosteal reaction and arising bony spicules should be considered a novel, essential, and sometimes the only radiographic finding of desmoplastic fibroma of the jaw bone in children in the early stage. An early diagnosis with clinical and advanced radiographic evaluations, such as CBCT, and subsequent proper treatment result in the preservation of more tissue and less morbidity, with expectations for a better prognosis. It should be noted that selecting the proper location of biopsy is very crucial in these cases. Imaging features can help clinicians avoid missing the diagnosis because histopathological findings cover a wide range of differential diagnoses.