Extraskeletal osteoma of the hand.

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(1)128. C A S E R E P O RT. Extraskeletal Osteoma of the Hand Y ick-Fung Jim, Hui-Yi Chen, Lien-Feng Chou. 1. 1. Department of Radiology, China Medical University Hospital, Taichung; Section of Radiology, Fong-Yuan Hospital, Department of Health, Executive Yuan, Fongyuan, Taiwan.. Osteoma is a common benign bone tumor, usually occurring inside the frontal sinuses and the mandible. The size of the lesion is usually small. It may induce sinusitis if it occurs inside the paranasal sinus. Extraskeletal osteoma is rare in soft tissue. A 67-year-old man presented with a lesion on the palm of his right hand; the lesion had been present for more than 10 years. Radiograph and magnetic resonance imaging of his hand provided adequate information for a differential diagnosis of extra-skeletal osteoma to be made before operation. The tumor was completely resected. Pathology confirmed extra-skeletal osteoma. To the best of our knowledge, this is the first case of extraskeletal osteoma of hand. ( Mid Taiwan J Med 2006;11:128-31 ). Key words extraskeletal osteoma, hand. INTRODUCTION. Osteoma usually occurs inside paranasal sinuses, especially frontal sinuses and the mandible. It may induce paranasal sinusitis. When osteoma occurs in soft tissue, it is called extraskeletal osteoma; it is extremely rare, especially in the hands. We present a case of extraskeletal osteoma located in soft tissue of a patient's right hand. CASE REPORT. A 67-year-old man presented with a lesion on the palm of his right hand. The lesion had been present for more than 10 years but the patient had not paid much attention to it until he noticed that it had been enlarging in recent months. He therefore visited our hospital. No history of trauma, no local tenderness and no painful sensation was noted. The lesion was about 2 centimeters in diameter. Physical examination revealed that it was nodular and hard in Received : 12 October 2005. Revised : 4 November 2005. Accepted : 11 November 2005. Address reprint requests to : Yick-Fung Jim, Department of Radiology, China Medical University Hospital, 2 Yuh-Der Road, Taichung 404, Taiwan.. consistency. No local or radiating pain was detected. Radiographs of the hand were taken in antero-posterior and oblique projections (Figs. 1A, 1B). They showed that the lesion consisted of high radiopaque density, compatible with bone trabeculae, and was located on the palmar side of the hand. The margin of the lesion was welldefined and no evidence of direct contact with the adjacent metacarpal bones was noted. T1 and T2 weighted magnetic resonance imaging (MRI) scans (Figs. 2A, 2B) revealed that the lesion was located entirely inside the soft tissue between the middle and ring fingers. No evidence of contact with the adjacent bones was noted. The lesion was about 2 centimeters in diameter and the margin was well defined. The signal intensity of the lesion was relatively homogenous; no evidence of necrosis or bleeding inside the lesion was noted. The lesion showed high signal intensity on both T1WI and T2WI scans, compatible with that of bone marrow. Based on radiographic and MR imaging findings, a bone-forming tumor was suspected and an extra-skeletal osteoma was included in the differential diagnosis..

(2) Y ick-Fung Jim, et al.. 129. DISCUSSION. A. B. Fig. 1. A: Radiograph of hand in AP projection shows a mass lesion of high density at the soft tissue between the third and fourth fingers. Bone trabeculae inside is evident. B: Radiograph of the right hand in oblique projection shows the lesion in the soft tissue.. A. B. Fig. 2. A: T1WI of the right hand. B: T2WI of the right hand. They show high signal intensity of the lesion, similar to that of normal bone marrow.. The patient underwent a near-margin resection and the tumor was resected successfully. Pathology revealed that the tumor was about 2 centimeters in diameter and consisted of normal bone trabeculae and fatty marrow; an extraskeletal osteoma was diagnosed (Fig. 3). Radiograph of the patient's hand at follow-up confirmed that the tumor had been completely resected. He recovered well after the operation and had no complications at his most recent visit to our clinic.. Osteoma is a benign, often asymptomatic neoplasm consisting of well-differentiated mature bone [1]. Osteomas of the paranasal sinuses are slow-growing benign tumors most frequently found in the frontal sinus in 47% to 80% of cases [2]. Osteomas are rare bone tumors and occur in the following sites: mastoid [3], the mandibular condyle [4], ulna [5], thyroid cartilage [6] and larynx [7]. An osteoma is a dense protrusion of normal bone. The lesions are confined to areas of the bone that are normally produced by the periosteal membrane [8]. Osteomas usually occur in the skull and facial bones; however, they may be present in the pelvis or tubular bones of extremities. Diagnosis is based on imaging studies. Extra-skeletal osteoma has the same internal components as that of osteoma of bone; they show the same pattern and features on radiographs. High radiopaque density of the lesion is present; bone trabecular pattern may be demonstrated. Osteoma of soft tissue should be considered when mature bone tissue is detected in soft tissue [8]. Osteomas of soft tissue are extremely uncommon. They generally occur in the head, usually in the posterior portion of the tongue, or in the thigh [9]. Our patient's osteoma occurred in the soft tissue of the right hand. Some atypical sites of osteomas of soft tissue include the base of the tongue [8,10] and the ovary [11]. Recognition of this benign bone tumor is especially important to avoid misdiagnosis of other, potentially more aggressive types of malignancies such as osteosarcoma or chondrosarcoma. Dense calcification or bone marrow is characteristic of the tumor and may be relied upon to exclude alternative soft tissue lesions. Ma'luf et al suggested that trauma might be a factor in the pathogenesis of osteoma [12]. Soft tissue osteoma is generally regarded as a benign bone tumor, however, Kasper et al proposed that it may be a reactive lesion [13]. Metaplastic ossification due to tumor or inflammation is one of the differential diagnoses;.

(3) 130. Extraskeletal Osteoma of the Hand. REFERENCES. Fig. 3. The mass consisted of normal bone trabeculae and fatty tissue.. detailed history of the patient can aid in the inclusion or exclusion of metaplastic ossification. Myositis ossifican is another differential diagnosis; the correct diagnosis can be made if we carefully examine any trauma history, and the sequential change of ossification inside the lesion. Once discovered, osteomas usually remain unchanged on series studies. Our patient had the lesion for more than 10 years. However, he felt that the mass had become larger recently. Surgical intervention was indicated to eliminate any possibility of malignancy since histopathologic confirmation of the tumor is the definitive method for diagnosis. MRI scan provides valuable information about soft tissue. The contour and margin of the lesion can be demonstrated in three dimensional planes. The nature of the lesion may be predicted if the lesion consists mainly of fatty tissue or bone marrow. The lesion in our patient consisted of bone marrow; therefore, extra-skeletal osteoma was included in our differential diagnosis.. 1. Johann AC, de Freitas JB, de Aguiar MC, et al. Peripheral osteoma of the mandible: case report and review of the literature. [Review] J Craniomaxillofac Surg 2005;33:276-81. 2. Dispenza C, Saraniti C, Ferrara S, et al. Frontal sinus osteoma and palpebral abscess: case report. Rev Laryngol Otol Rhinol (Bord) 2005;126:49-51. 3. Magliulo G, Pulice G, Mastoid osteoma. An Otorrinolaringol Ibero Am 2005;32:271-8. 4. Ortakoglu K, Gunaydin Y, Aydintug YS, et al. Osteoma of the mandibular condyle: report of a case with 5-year follow-up. Mil Med 2005;170:117-20. 5. Chikuda H, Goto T, Ishida T, et al. Juxtacortical osteoma of the ulna. J Orthop Sci 2002;7:721-3. 6. Redman AG, Hide IG, Zammit-Maempel I. Osteoma of the thyroid cartilage--an unusual cause of difficult intubation. Br J Radiol 2000;73:899-900. 7. Batti JS, Abramson A. First report of a case of osteoma of the larynx. Ear Nose Throat J 2000;79: 564-8. 8. Resnick D. Tumors and tumor-like lesions of soft tissues. In: Resnick D, 3rd eds. Bone and Joint Imaging. Eliser Inc. 2005:1225. 9. Lekas MD, Sayegh R, Finkelstein SD. Osteoma of the base of the tongue. Ear Nose Throat J 1997;76:827-8. 10. Yang SW, Chen CY, Lin CY. Lingual osteoma: case report. Chang Gung Med J 2000;23:498-502. 11. Celik C, Gungor S, Acar A, et al. Ovarian osteoma. Arch Gynecol Obstet 2003;268:222-3. 12.Ma'luf RN, Ghazi NG, Zein WM, et al. Orbital osteoma arising adjacent to a foreign body. Ophthal Plast Reconstr Surg 2003;19:327-30. 13.Kasper HU, Adermahr J, Dienes HP. Soft tissue osteoma: tumour entity or reactive lesion? Paraarticular soft tissue osteoma of the hip. Histopathology 2004;44:91-3..

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