II. Case report

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口腔病理科 On-Line KMU Student Bulletin

原文題目(出處)： Odontogenic myxoma of the mandible. Case Rep Dent 2012, Article ID 214704

原文作者姓名： Rakesh Kumar Manne,Venkata suneel Kumar, P Venkata Sarath, Lavanya Anumula, Sridhar Mundlapudi, Rambabu Tanikonda

通訊作者學校： Department of Oral Medicine and Radiology, Narayana Dental College and Hospital, Chintareddypalem, Nellore Andhra Pradesh, India

報告者姓名(組別)： Intern F 組廖官瑄

報告日期： 2013/2/4

內文：

I. Introduction

Odontogenic myxomas (OMs) are benign tumors derived from embryonic mesenchymal elements of dental anlage. It appears to originate from dental papilla, follicle, or periodontal ligament. According to the World Health Organization (WHO), OM is classified as benign tumor of ectomesenchymal origin with or without odontogenic epithelium.

1. Odontogenic origin:

- exclusive location in the tooth bearing areas of the jaws, its occasional association with missing or unerupted teeth, and the presence of odontogenic epithelium

- consistent with odontogenic ectomesenchyme, could also represent a more primitive fibroblastic or undifferentiated tissue

2. Young adults affected mostly in their second and third decade of life 3. Female predilection

4. Occur both in bone and soft tissue

5. Majority of these tumors occur in the mandible 6. Slow-growing, painless, and site-aggressive tumors

7. Larger lesions may cause tooth displacement and cortical bone expansion

8. May vary from a unilocular radiolucency to a multicystic lesion with well-defined or diffused margins with fine, bony trabeculae within its interior structure expressing a “honey combined”, “soap bubble,” or “tennis racket”

appearance

9. A unilocular appearance may be seen more commonly in children and in anterior parts of the jaws. Root resorption is rarely seen, and the tumor is often scalloped between the roots.

10. Not encapsulated, thus promoting significant infiltration into the adjacent medullar bone

11. Exhibits abundant extracellular production of ground substance and thin fibrils by the delicate spindle-shaped cells

12. The treatment of choice for OM is surgical excision by enucleation, curettage, or block resection.

13. Carries a high recurrence rate (25% is reported when more conservative treatments are used)

II. Case report

1. General data：A 19-year-old male patient

2. Chief complaint：a one-month history of a mild pain and swelling in the right posterior mandible. Pain is intermediate and usually seen on mastication.

Initially, the swelling was small in size and showed a gradual increase to its

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present dimensions.

3. Past medical history & family history: unremarkable

4. Clinical examination: Firm, non-tender swelling expanding the buccal and lingual cortices of the mandible, extending from right first premolar region to third molar region, and it obliterated the buccal vestibule. Skin over the swelling was normal, and there was no history of paresthesia.

5. Panoramic radiograph: Large well-defined, sclerotic margined, multilocular radiolucent lesion with “soap bubble” appearance extending from the lower right canine to 1 cm distal to the third molar and also showed first molar mesial root resorption

6. Right mandibular lateral occlusal radiograph: multilocular radiolucent lesion with expansions of buccal and lingual cortices

7. Fine needle aspiration was performed to rule out odontogenic cysts, and results were negative.

8. Histopathological examination: rounded, stellate, and spindle-shaped mesenchymal cells arranged in a loose, myxoid stroma with few collagen fibrils.

9. Diagnosis: Odontogenic myxomas

10. Differential diagnosis: ameloblastoma, ameloblastic fibroma, odontogenic fibroma, central hemangioma, or odontogenic keratocyst

11. Treatment: Segmental resection of the right side mandible. Reconstruction was done by microvascular iliac bone grafting, and fixation was achieved with titanium plates.

12. Postoperative complications: iliac bone graft rejection, and sequestrated bone graft was removed 3 months later

13. 30 months follow-up: No recurrence was observed

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III. Discussion

1. The prevalence of OM is principally quoted between 0.04%and 3.7%. In Asia, Europe, and America, relative frequencies between 0.5% and 17.7%.

2. Comparison:

Odontogenic myxomas (OMs) Present case Age Lack of uniformity in the most common

group studies, most of the studies showed 22.7 to 36.9 years, and it is rarely seen in patients younger than 10 years of age or older than 50

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Site Mandible appears to be more frequently affected than the maxilla

Right post. mandible S/S Almost always asymptomatic, although

some patients present with progressive pain in lesions invading into surrounding structures with eventual neurological disturbances. Maxilla more aggressively than that of the mandible.

Invading with intermediate pain, and more aggressive, in spite of its mandibular occurrence

Radiographic appearance

Multilocular or unilocular radiolucencies.

Multilocular radiolucency with “soap bubble”

appearance 3. Surgical treatment modality:

- conservative (enucleation, curettage, and cryotherapy)

pros: (1) Don’t need reconstruction with fibular microsurgical flap.

(2) Less morbid intervention (3) Possibility of intraoral access (4) Absence of donor area

(5) A shorter hospitalization time

(6) Not interfering with facial growth in children (7) Low procedural cost

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cons: High recurrence rate (lack of capsule and infiltrative growth pattern) - Radical treatment of block resection

Advised by most authors over conservative treatment due to its invasive nature, large size, and recurrence history

Cons: posttreatment rehabilitation difficulties

- The conservative management of myxoma by excision and curettage with liquid nitrogen cryotherapy is an alternative method proposed to radical resection.

4. A minimum of five years of surveillance is required to confirm that the lesion has healed, and periodical clinical and radiographic follow-up should be maintained indefinitely irrespective of treatment modality applied to treat OM.

題號題目

1 Which histopathologic feature is not true in odontogenic myxoma?

(A) Mostly encapsulated

(B) infiltrative proliferation of spindle, bipolar, and stellate cells with bland nuclei

(C) Present within a mucinous/myxoid stroma that contains abundant hyaluronic acid

(D) Islands of odontogenic epithelium are noted in less than 10% of cases

答案( A) 出處：Oral Pathology p.375

題號題目

2 Which one is false?

(A) Odontogenic myxoma mostly occurs at age over 50 years old (B) Predilection of odontogenic myxoma is female prediletion.

(C) Lesion of odontogenic myxoma is a poorly circumscribed, multilocular, or honeycombed radiolucency

(D) Odontogenic myxoma is usually in the posterior maxilla or mandible

答案( A) 出處：Oral Pathology p.375