Intramuscular myxoma: a rare neck mass in a child

Pediatr Radiol (2002) 32: 120–122 DOI 10.1007/s00247-001-0603-5 Stanley J. Crankson Mohammed Al Namshan Khalid Al Mane Hanaa Bamefleh Received: 29 May 2001 Accepted: 24 August 2001 Published online: 13 December 2001 Ó Springer-Verlag 2001 S.J. Crankson (&) Æ M.A. Namshan Department of Surgery, King Fahad National Guard Hospital, P.O. Box 22490, Riyadh 11426, Kingdom of Saudi Arabia E-mail: [email protected] Tel.: +966-1-2520088 Fax: +966-1-2520140 CASE REPORT Intramuscular myxoma: a rare neck mass in a child Abstract Intramuscular myxoma (IM) is a true mesenchymal benign tumour which is rare in both adults and children. In children, it most commonly affects the heart, mandible or maxilla. We report a 5-yearold child with IM presenting as a posterolateral neck mass and review the literature. IM, although very rare, should be included in the differential diagnosis of neck masses in the paediatric age group. Keywords Ultrasound Æ CT Æ Head/neck Æ Neoplasms-Primary K.A. Mane Department of Radiology, King Fahad National Guard Hospital, Riyadh, Kingdom of Saudi Arabia H. Bamefleh Department of Pathology, King Fahad National Guard Hospital, Riyadh, Kingdom of Saudi Arabia Introduction Neck masses in children may be congenital, inflammatory or neoplastic, 90% being of a benign nature. Myxoma is a true, mesenchymal benign tumour of fibroblast origin that produces an excess of mucopolysaccharide and is incapable of producing mature collagen [1]. The tumour, histologically, resembles umbilical cord [2]. Myxoma can occur in a variety of locations including the heart, bones, skin, subcutaneous and aponeurotic tissue, genitourinary tract and skeletal muscle. Mainstream myxoma of soft tissue, a subdivision of myxoid lesions if intramuscular, is known as intramuscular myxoma (IM) [3]. Head and neck IM in adults have been reported in various muscles including geniohyoid, lateral part of the neck muscles, posterior part of neck muscles and in the forehead [2]. We present IM as a posterior neck mass in a child. Case report A gradually enlarging neck mass of 7 months’ duration was noticed in a 5-year-old girl. The mass was not preceded by trauma. Clinical examination revealed a 4-cm diameter, firm non-tender mass in the left posterior triangle just deep to the anterior border of trapezius muscle. The rest of the examination was unremarkable. US of the neck showed a multicystic mass whilst CT revealed a 4-cm diameter, encapsulated, low-density, septated cystic mass in the left posterior neck (Figs. 1, 2). Through a transverse cervical incision, a well-circumscribed, soft-to-firm multicystic mass containing mucoid and gelatinous material was totally excised. Histologically, the tumour was com- 121 posed of different cells, including small oval cells and spindle and stellate cells embedded in a myxomatous stroma containing few tiny blood vessels. There were no mitoses and no differentiated elements such as chondroblasts, lipoblasts or rhabdomyoblasts. The histological features were consistent with myxoma. There has not been a recurrence of the tumour at 1 year postoperative followup. Discussion Myxoma, a benign mesenchymal tumour, has a predilection for the heart, mandible, maxilla and soft tissue of the face in childhood [4]. IM is rare in patients younger than 20 years and most frequently occurs in female adults in the fourth to sixth decades of life; it tends to involve the muscles of the thigh, buttocks, upper arm and shoulder. It is a slow-growing tumour and presents as a painless mass for several months to years, as in this case. It is usually an asymptomatic solitary mass, but pressure on adjacent vascular or neuromuscular structures may be associated with symptoms. Because of the infrequent occurrence of IM, it may not even be suspected after radiological investigations. US may show a complex cyst of multiple fluid-filled clefts or cystic areas of various sizes within a well-demarcated intramuscular mass with no increased vascularity [5]. CT typically reveals a cystic-looking mass, as was this case, with an attenuation value greater than water, but less than surrounding normal muscle and no enhancement after IV administration of contrast medium [6]. On MRI, IM is seen to have sharp borders with homogeneous low-signal intensity, lower than skeletal muscle, on T1-weighted images and homogeneous high Fig. 1 US of the neck shows a lobulated hypoechoic mass with multiple echogenic septa and an echogenic capsule intensity, brighter than fat, on T2-weighted images [7]. All these radiological features, although typical of IM, may be mimicked by any fluid-filled lesion. Differential diagnoses include cystic hygroma, cystic teratoma, lipoma, haematoma, abscess, lymph nodes, neuroma and myxoid sarcoma. Nevertheless, imaging can be helpful in preoperative planning, especially in establishing the relationship of the tumour to the adjacent neurovascular structures. Based on the clinical and radiological findings, a diagnosis can be suggested. However, excision or core biopsy is often necessary to establish a definitive diagnosis. Fine-needle aspiration biopsy (FNAB) has been used in some cases of IM to establish a diagnosis. USguided FNAB in four cases reported by Fornage and Romsdahl [5] was associated with cytological diagnosis of IM in only one. Caraway et al. [8] performed MRI followed by FNAB in six patients. They concluded that although the cytological features were suggestive of IM, particularly in paediatric patients, they are generally regarded as lacking specificity. On the other hand, largecore needle biopsy may be used preoperatively followed by excision in some cases. Surgical treatment includes enucleation, simple excision or wide local excision of the tumour. In a review by Nielsen et al. [9] of 32 patients with IM, there was no recurrence or metastasis. Therefore, with no recurrence reported with IM, local excision with a good margin seems adequate [1, 9]. In contrast, bony myxomas have a high rate of recurrence after conservative excision such as enucleation or curettage [4]. Fig. 2 CT of the neck shows a septated, well-defined low-density mass in the left posterior neck, which does not enhance with IV contrast medium 122 Multiple tumours are rare and are usually associated with monostotic or polyostotic fibrous dysplasia and McCune-Albright syndrome [1,2]. Fibrous dysplasia in association with IM is known as Mazabraud’s syndrome [10]. In this condition, IM are usually located in the vicinity of the bones most severely affected by fibrous dysplasia, most commonly the thigh. Therefore, the possibility of IM associated with osseous fibrous dysplasia should always be considered. IM is a rare benign tumour of head and neck in the paediatric age group. It is a slow-growing painless tumour in which typical radiological features may be seen on CT or MRI. The diagnosis may be established after biopsy, but local excision and histological examination are preferable for confirmation. IM is not associated with local recurrence or metastasis. It should be included in the differential diagnosis of neck masses in children. Acknowledgements We wish to thank Mel Rabago for typing the manuscript. References 1. Shugar JM, Som PM, Meyers RJ, et al (1987) Intramuscular head and neck myxoma: report of a case and review of the literature. Laryngoscope 97: 105–107 2. Nishijima W, Tokita N, Watanabe I, et al (1985) Intramuscular myxoma of the neck. Arch Otolaryngol 111: 699– 701 3. Allen PW (2000) Myxoma is not a single entity: a review of the concept of myxoma. Ann Diagn Pathol 4: 99–123 4. Andrews T, Kountakis SE, Maillard AJ (2000) Myxomas of the head and neck. Am J Otolaryngol 21: 184–189 5. Fornage BD, Romsdahl MM (1994) Intramuscular myxoma: sonographic appearance and sonographically guided needle biopsy. J Ultrasound Med 13: 91–94 6. Hashimoto H, Tsuneyoshi M, Daimaru Y, et al (1986) Intramuscular myxoma. A clinicopathologic, immunohistochemical and electron microscopic study. Cancer 58: 740–747 7. Abdelwahab AF, Kenan S, Hermann G, et al (1992) Intramuscular myxoma: magnetic resonance features. Br J Radiol 65: 485–490 8. Caraway NP, Staerkel GA, Fanning CV, et al (1994) Diagnosing intramuscular myxoma by fine-needle aspiration: a multidisciplinary approach. Diagn Cytopathol 11: 255–261 9. Nielsen GP, O’Connell JX, Rosenberg AE (1998) Intramuscular myxoma: a clinicopathologic study of 51 cases with emphasis on hypercellular and hypervascular variants. Am J Surg Pathol 22: 1222–1227 10. Walker RE, Schwartz RK, Gale DR (1999) Mazabraud’s syndrome (intramuscular myxomas associated with fibrous dysplasia). AJR 173: 800–802