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Intramuscular lipoma in the masseter muscle: a case report
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British Journal of Oral and Maxillofacial Surgery 52 (2014) e21–e23
Short communication
Intramuscular lipoma in the masseter muscle: a case report Go Tsumuraya a , Hiroyuki Yamada b,∗ , Hajime Shimizu b , Yoshiki Hamada b a b
Department of Oral and Maxillofacial Surgery, Syounai Amarume Hospital, Yamagata, Japan Department of Oral and Maxillofacial Surgery, School of Dental Medicine, Tsurumi University, Yokohama, Japan
Accepted 23 January 2014 Available online 17 February 2014
Abstract This is the first report to our knowledge of an intramuscular lipoma that arose in the masseter muscle. Excision biopsy under general anaesthesia showed that the mass could easily be separated from the surrounding soft tissues on the lateral side, but was firmly adherent to the muscle on the medial side, so complete excision required resection of part of the masseter. Histopathological examination showed that it was an intramuscular lipoma. Two years and 6 months postoperatively there was no evidence of recurrence. © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Intramuscular lipoma; Masseter muscle; Head and neck
Introduction
Case report
Lipomas are benign tumours characterised by proliferation of mature white adipocytes, and are the most common mesenchymal neoplasms of the soft tissues in adults. Intramuscular lipomas arise within skeletal muscle fibres at various locations, typically during middle to late adulthood.1 They usually present as well-circumscribed, painless, rubbery, solitary nodules, and are relatively common in the extremities. However, they are rare in the head and neck, where the most common site is the tongue.2,3 A few cases of an intramuscular lipoma that has arisen in the temporal muscle have been reported,4,5 but this is to our knowledge the first reported case of a lipoma that arose from the masseter muscle.
A 58-year-old man was referred to our hospital in February 2010 with a painless nodule in his right cheek that he had first noticed about 2 years previously. He had a history of cancer of the large bowel (stage IIIa), which had been resected 2 years previously followed by postoperative chemotherapy. There was no history of injury to the face. On physical examination there was a soft mobile mass in his right cheek that measured 45 mm × 35 mm. The overlying skin and oral mucosa looked normal, and there was no bruit or pulsation over the mass. There were no signs of neuroparalysis, cervical lymphadenopathy, or trismus. Magnetic resonance imaging (MRI) showed a mass 33 mm × 30 mm × 15 mm in the right masseter muscle. The mass had high signal intensity on axial T1-weighted and T2-weighted images and low signal intensity on short tau inversion recovery images. The lateral margin was fairly well-defined, but the medial margin was not (Fig. 1). The clinical diagnosis was intramuscular lipoma in the right masseter muscle, but well-differentiated liposarcoma was not completely excluded based on the MRI. Excision biopsy of the mass through a 4-cm intraoral incision under general anaesthesia showed a soft, yellow mass within the muscle (Fig. 2), which was easily separated from the
∗ Corresponding author at: Department of Oral and Maxillofacial Surgery, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi Tsurumi-ku, Yokohama 230-8501, Japan. Tel.: +81 45 580 8332; fax: +81 45 582 0459. E-mail address: [email protected] (H. Yamada).
0266-4356/$ – see front matter © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2014.01.013
e22
G. Tsumuraya et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) e21–e23
Fig. 3. Photomicrograph showing proliferation of mature adipocytes infiltrating the muscle fibres. The adipocytes show no cellular atypia or irregularity. There are no mitoses (haematoxylin and eosin (original magnification 200×).
Fig. 1. Preoperative MRI (axial T1-weighted image) showing a mass with high signal intensity. The lateral margin is fairly well-defined, but the medial margin is not well-defined.
surrounding soft tissues on the lateral side. However, it was firmly adherent to the muscle on the medial side, and complete excision required resection of part of the muscle. Histological examination of sections of the mass stained with haematoxylin and eosin showed proliferation of mature adipocytes that had infiltrated the muscle fibres. The adipocytes showed no cellular atypia or irregularity, and we saw no mitoses (Fig. 3). The histopathological diagnosis was intramuscular lipoma. The postoperative course was uneventful and 2 years and 6 months postoperatively there was no evidence of recurrence. He was able to chew normally.
Discussion An intramuscular lipoma can be differentiated from a well-differentiated liposarcoma by both imaging and histopathological examination.1 An irregular interface between the lipoma and the muscle on radiographic images indicates infiltration into the muscle.6 In the present case the tumour was adherent to the masseter muscle on the medial side, and separation of the tumour from the muscle was difficult. Senchenkov and Werning 7 reported that computed tomography and MRI findings could not differentiate completely between intramuscular lipomas and liposarcomas. Overlapping histopathological features may also make definitive diagnosis difficult. A diagnosis of liposarcoma requires recognition of atypical cells by careful inspection and extensive sampling.8 It has been suggested that a lipoma is likely to present as a solitary mass whereas a liposarcoma tends to present with multiple masses.6 Although intramuscular lipoma has been reported to have a high recurrence rate,9 only one case of intramuscular lipoma in the head and neck with recurrence has been reported to our knowledge. 6 This was a 5-year-old child who developed two separate recurrences.6 The first happened 2 years after the first operation, and the second 18 months after the second operation. Histopathological examination showed that the tumour was partially encapsulated at the first operation and poorly circumscribed at the second operation. In our adult case, excision of the tumour included resection of normal muscle (where the border of the tumour was not clear or regular) to achieve complete excision.
Conflict of interest Fig. 2. Operative photograph showing a yellow mass in the incised masseter muscle.
None declared.
G. Tsumuraya et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) e21–e23
References 1. Kleihues P, Sobin LH. W.H.O. classification of tumours, pathology & genetics. In: Tumours of soft tissue and bone. Lyons: IARC Press; 2003. 2. Furlong MA, Fanburg-Smith JC, Childers EL. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases. Oral Surg Oral Med Oral Pathol Radiol Endod 2004;98:441–50. 3. Fregnani ER, Pires FR, Falzoni R, Lopes MA, Vargas PA. Lipomas of the oral cavity: clinical findings, histological classification and proliferative activity of 46 cases. Int J Oral Maxillofac Surg 2003;32:49–53. 4. Scolozzi P, Lombardi T, Maire G, Pedeutour F, Richter M. Infiltrating intramuscular lipoma of the temporal muscle. A case report with molecular cytogenetic analysis. Oral Oncol 2003;39:316–22.
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5. Uemura T, Suse T, Yokoyama T, Mitsukawa N, Yoshikawa A. Intramuscular benign lipoma of the temporalis muscle. Scand J Plast Reconstr Surg Hand Surg 2002;36:231–4. 6. Scherl MP, Som PM, Biller HF, Shah K. Recurrent infiltrating lipoma of the head and neck. Case report and literature review. Arch Otolaryngol Head Neck Surg 1986;112:1210–2. 7. Senchenkov A, Werning JW. Radiographic assessment of the infiltrating retropharyngeal lipoma. Otolaryngol Head Neck Surg 2001;125:658–60. 8. Piperi E, Tosios KI, Nikitakis NG, et al. Well-differentiated liposarcoma/atypical lipomatous tumor of the oral cavity: report of three cases and review of the literature. Head Neck Pathol 2012;6:354–63. 9. Dionne GP, Seemayer TA. Infiltrating lipomas and angiolipomas revisited. Cancer 1974;33:732–8.
British Journal of Oral and Maxillofacial Surgery 52 (2014) e21–e23
Short communication
Intramuscular lipoma in the masseter muscle: a case report Go Tsumuraya a , Hiroyuki Yamada b,∗ , Hajime Shimizu b , Yoshiki Hamada b a b
Department of Oral and Maxillofacial Surgery, Syounai Amarume Hospital, Yamagata, Japan Department of Oral and Maxillofacial Surgery, School of Dental Medicine, Tsurumi University, Yokohama, Japan
Accepted 23 January 2014 Available online 17 February 2014
Abstract This is the first report to our knowledge of an intramuscular lipoma that arose in the masseter muscle. Excision biopsy under general anaesthesia showed that the mass could easily be separated from the surrounding soft tissues on the lateral side, but was firmly adherent to the muscle on the medial side, so complete excision required resection of part of the masseter. Histopathological examination showed that it was an intramuscular lipoma. Two years and 6 months postoperatively there was no evidence of recurrence. © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Keywords: Intramuscular lipoma; Masseter muscle; Head and neck
Introduction
Case report
Lipomas are benign tumours characterised by proliferation of mature white adipocytes, and are the most common mesenchymal neoplasms of the soft tissues in adults. Intramuscular lipomas arise within skeletal muscle fibres at various locations, typically during middle to late adulthood.1 They usually present as well-circumscribed, painless, rubbery, solitary nodules, and are relatively common in the extremities. However, they are rare in the head and neck, where the most common site is the tongue.2,3 A few cases of an intramuscular lipoma that has arisen in the temporal muscle have been reported,4,5 but this is to our knowledge the first reported case of a lipoma that arose from the masseter muscle.
A 58-year-old man was referred to our hospital in February 2010 with a painless nodule in his right cheek that he had first noticed about 2 years previously. He had a history of cancer of the large bowel (stage IIIa), which had been resected 2 years previously followed by postoperative chemotherapy. There was no history of injury to the face. On physical examination there was a soft mobile mass in his right cheek that measured 45 mm × 35 mm. The overlying skin and oral mucosa looked normal, and there was no bruit or pulsation over the mass. There were no signs of neuroparalysis, cervical lymphadenopathy, or trismus. Magnetic resonance imaging (MRI) showed a mass 33 mm × 30 mm × 15 mm in the right masseter muscle. The mass had high signal intensity on axial T1-weighted and T2-weighted images and low signal intensity on short tau inversion recovery images. The lateral margin was fairly well-defined, but the medial margin was not (Fig. 1). The clinical diagnosis was intramuscular lipoma in the right masseter muscle, but well-differentiated liposarcoma was not completely excluded based on the MRI. Excision biopsy of the mass through a 4-cm intraoral incision under general anaesthesia showed a soft, yellow mass within the muscle (Fig. 2), which was easily separated from the
∗ Corresponding author at: Department of Oral and Maxillofacial Surgery, School of Dental Medicine, Tsurumi University, 2-1-3 Tsurumi Tsurumi-ku, Yokohama 230-8501, Japan. Tel.: +81 45 580 8332; fax: +81 45 582 0459. E-mail address: [email protected] (H. Yamada).
0266-4356/$ – see front matter © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bjoms.2014.01.013
e22
G. Tsumuraya et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) e21–e23
Fig. 3. Photomicrograph showing proliferation of mature adipocytes infiltrating the muscle fibres. The adipocytes show no cellular atypia or irregularity. There are no mitoses (haematoxylin and eosin (original magnification 200×).
Fig. 1. Preoperative MRI (axial T1-weighted image) showing a mass with high signal intensity. The lateral margin is fairly well-defined, but the medial margin is not well-defined.
surrounding soft tissues on the lateral side. However, it was firmly adherent to the muscle on the medial side, and complete excision required resection of part of the muscle. Histological examination of sections of the mass stained with haematoxylin and eosin showed proliferation of mature adipocytes that had infiltrated the muscle fibres. The adipocytes showed no cellular atypia or irregularity, and we saw no mitoses (Fig. 3). The histopathological diagnosis was intramuscular lipoma. The postoperative course was uneventful and 2 years and 6 months postoperatively there was no evidence of recurrence. He was able to chew normally.
Discussion An intramuscular lipoma can be differentiated from a well-differentiated liposarcoma by both imaging and histopathological examination.1 An irregular interface between the lipoma and the muscle on radiographic images indicates infiltration into the muscle.6 In the present case the tumour was adherent to the masseter muscle on the medial side, and separation of the tumour from the muscle was difficult. Senchenkov and Werning 7 reported that computed tomography and MRI findings could not differentiate completely between intramuscular lipomas and liposarcomas. Overlapping histopathological features may also make definitive diagnosis difficult. A diagnosis of liposarcoma requires recognition of atypical cells by careful inspection and extensive sampling.8 It has been suggested that a lipoma is likely to present as a solitary mass whereas a liposarcoma tends to present with multiple masses.6 Although intramuscular lipoma has been reported to have a high recurrence rate,9 only one case of intramuscular lipoma in the head and neck with recurrence has been reported to our knowledge. 6 This was a 5-year-old child who developed two separate recurrences.6 The first happened 2 years after the first operation, and the second 18 months after the second operation. Histopathological examination showed that the tumour was partially encapsulated at the first operation and poorly circumscribed at the second operation. In our adult case, excision of the tumour included resection of normal muscle (where the border of the tumour was not clear or regular) to achieve complete excision.
Conflict of interest Fig. 2. Operative photograph showing a yellow mass in the incised masseter muscle.
None declared.
G. Tsumuraya et al. / British Journal of Oral and Maxillofacial Surgery 52 (2014) e21–e23
References 1. Kleihues P, Sobin LH. W.H.O. classification of tumours, pathology & genetics. In: Tumours of soft tissue and bone. Lyons: IARC Press; 2003. 2. Furlong MA, Fanburg-Smith JC, Childers EL. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases. Oral Surg Oral Med Oral Pathol Radiol Endod 2004;98:441–50. 3. Fregnani ER, Pires FR, Falzoni R, Lopes MA, Vargas PA. Lipomas of the oral cavity: clinical findings, histological classification and proliferative activity of 46 cases. Int J Oral Maxillofac Surg 2003;32:49–53. 4. Scolozzi P, Lombardi T, Maire G, Pedeutour F, Richter M. Infiltrating intramuscular lipoma of the temporal muscle. A case report with molecular cytogenetic analysis. Oral Oncol 2003;39:316–22.
e23
5. Uemura T, Suse T, Yokoyama T, Mitsukawa N, Yoshikawa A. Intramuscular benign lipoma of the temporalis muscle. Scand J Plast Reconstr Surg Hand Surg 2002;36:231–4. 6. Scherl MP, Som PM, Biller HF, Shah K. Recurrent infiltrating lipoma of the head and neck. Case report and literature review. Arch Otolaryngol Head Neck Surg 1986;112:1210–2. 7. Senchenkov A, Werning JW. Radiographic assessment of the infiltrating retropharyngeal lipoma. Otolaryngol Head Neck Surg 2001;125:658–60. 8. Piperi E, Tosios KI, Nikitakis NG, et al. Well-differentiated liposarcoma/atypical lipomatous tumor of the oral cavity: report of three cases and review of the literature. Head Neck Pathol 2012;6:354–63. 9. Dionne GP, Seemayer TA. Infiltrating lipomas and angiolipomas revisited. Cancer 1974;33:732–8.