Neck dissection for treatment of supraglottic carcinoma associated with deep-seated intermuscular lipoma in the neck: A case report

Abstract

Lipomas are superficial tumors that occur primarily in the subcutaneous region and very rarely occur deeply within or between the muscle layers. No reports to date have described cervical lipomas in patients with head and neck cancer who underwent neck dissection. We herein report a case involving a 72-year-old woman with supraglottic carcinoma complicated by a cervical lipoma who underwent simultaneous neck dissection and lipoma removal. The lipoma was a deep-seated intermuscular lipoma arising in the longus cervicis muscle. We initially considered that the lipoma would be removed en bloc with neck dissection, but the imaging findings clearly indicated that the tumor was located more deeply than the prevertebral layer of the deep cervical fascia and outside the range of neck dissection. The lipoma was removed by incision of the prevertebral fascial layer following neck dissection, and no complications occurred.

Introduction

Lipomas are the most common mesenchymal benign tumors. They occur mainly in the trunk and extremities, but they are also frequently encountered in the head and neck region. Generally, most lipomas are superficial tumors located in the subcutaneous region adjacent to the superficial fascial layer. However, deep-seated lipomas located deep under the enclosing fascial layer also sometimes develop. They arise from the muscular fascia or within the muscle and are called intramuscular lipomas. Deep-seated intramuscular lipomas account for 1.8% of all lipomas and are very rare entities [1]. Intramuscular lipomas are classified into 2 types: the infiltrative type, which occurs in the muscle, and the well-circumscribed type, which occurs between the muscle layers. The former is called narrowly defined intramuscular lipoma, and the latter is called intermuscular lipoma [1,2].

We experienced a case in which neck dissection (ND) was performed for treatment of a supraglottic carcinoma with lymph node metastasis in the neck complicated by a deep cervical lipoma. To the best of our knowledge, there have been no reports of an intermuscular lipoma in the longus cervicalis muscle or ND complicated by a lipoma. This case is herein presented with detailed intraoperative and imaging findings.

Case presentation

A 72-year-old woman was admitted to our hospital. She had a supraglottic squamous cell carcinoma and had been referred from the nearby general hospital with the chief complaint of sore throat and hoarseness for 1 month. She had a neoplastic lesion extending from the laryngeal surface of the epiglottis to the left epiglottic vallecula, aryepiglottic fold, false vocal fold, and posterior cricoid region. She had left vocal cord paralysis and a narrowed airway, and she was hospitalized for tracheostomy the same day. Computed tomography performed on admission revealed a T3N2cM0 supraglottic carcinoma with lymph node metastasis on both sides of the neck. Computed tomography also incidentally showed a lesion suspicious for a lipoma in the right neck (Fig. 1A). An additional magnetic resonance imaging study suggested that the lipoma in the right neck was located deeper within the prevertebral layer of the deep cervical fascia (Figs. 1B and C). Metastatic lymph nodes were located more superficially than the prevertebral fascial layer, and they showed no continuity with the lipoma (Fig. 1D). A soft mass was palpated in this region, but no subjective symptoms were observed.

Fig. 1.

Imaging findings of the deep-seated intermuscular lipoma. (A) Contrast-enhanced computed tomography showed the lipoma as a hypodense mass (white arrowheads). (B) T1-weighted MRI showed a high-intensity mass. The black arrowhead indicates a muscle bundle of the longus colli muscle enclosed within the lipoma. (C) Fat-suppressed T1-weighted MRI showed signal suppression in the mass. The yellow dashed line indicates the deep layer of the deep cervical fascia, and the mass was located deep to this line. (D) Contrast-enhanced computed tomography. Metastatic lymph nodes are indicated by white arrows. These lymph nodes were definitely located in the superficial layer rather than the layer in which the lipoma was present. *Supraglottic tumor with paraglottic space invasion. MRI, magnetic resonance imaging; CA, carotid artery; IJV, internal jugular vein.

CA, carotid artery; IJV, internal jugular vein; MRI, magnetic resonance imaging.

Nineteen days after the first visit, total laryngectomy with partial basal tongue resection, total thyroidectomy, bilateral ND, and right lipoma removal were performed under general anesthesia. The lipoma was asymptomatic, but we anticipated that if it enlarged in the future, reoperation on the neck would be extremely difficult. Therefore, we performed simultaneous resection. Because the lipoma was located deep to the prevertebral layer of the deep cervical fascia and outside the area of neck dissection, the lipoma was removed after the dissected material had been elevated to the medial border of the carotid artery. The lipoma was located between the muscle layers of the longus colli muscle, indicating a deep-seated intermuscular lipoma (Figs. 2A–C). Histopathological examination revealed nodules composed of well-circumscribed adipose tissue (Fig. 3). The postoperative course was uneventful, and the patient was discharged home approximately 4 weeks after the operation. Three years 6 months after the treatment, no recurrence of the cancer or lipoma was observed.

Fig. 2.

Neck dissection and lipoma removal findings. (A, B) Right lateral neck dissection. (C–E) Lipoma removal. The lipoma was located deeper than the prevertebral layer of the deep cervical fascia (white arrowhead) and outside the area of neck dissection. The dissected tissue is indicated by gray arrowheads. The lipoma was located deeper than the longus colli muscle (black arrowhead), and the muscle bundle of the longus colli was embedded in the lipoma. (D) Removal of the lipoma. (E) Surgical wound findings after lipoma extraction.

Fig. 3.

Histopathological findings. Examination revealed a well-circumscribed lipoma composed of adipose cells, without infiltrative muscle tissue. Scale bar: 200 µm.

Discussion

Deep-seated lipomas in the head and neck region have been reported within the sternocleidomastoid muscle and include pathologically well-circumscribed types [3] and infiltrative types [4]. Reports of coexisting head and neck cancer are even rarer. Although 1 report described the development of metastatic foci of laryngeal cancer within an intramuscular lipoma of the thigh [5], there have been no reports to date of deep-seated lipomas in the surgical field of ND. Among intramuscular lipomas, the reported incidence of the infiltrative type is 87%, and that of the well-circumscribed type (as in the present case) is only 13% [1]. In addition, the risk of recurrence is generally higher for the infiltrative type, and differentiation from well-differentiated liposarcoma is important; however, the risk of recurrence of the well-circumscribed type is considered low [1,2].

Conservative ND is a surgical procedure in which adipose and lymphatic tissues on the superficial side of the deep layer of the deep cervical fascia are dissected while preserving certain nerves and blood vessels. The area beyond the prevertebral layer of the deep cervical fascia is outside the range of dissection. Because the lipoma in this case was softly palpable from the body surface, we initially assumed that the lipoma would be removed en bloc with the ND. However, as shown by magnetic resonance imaging, the tumor was located deeper than the prevertebral layer of the deep cervical fascia, and the imaging clearly showed that the fascicles of the longus colli muscle penetrated between the lipomas from the surface. Preoperative diagnosis and an accurate preoperative understanding of the anatomical positional relationships are the basis of surgical planning. If the operation had been performed under inappropriate preoperative planning in the present case, or if an inexperienced surgeon had incorrectly decided to include the lipoma within the dissected tissue because of inadequate anatomical knowledge, the nerves running in the surface of the deep layer of the deep cervical fascia may have been damaged or unnecessary bleeding may have occurred. Although such deep intermuscular or intramuscular lipomas are very rare in patients requiring ND, it is important for head and neck surgeons to recognize these rare conditions. Our experience in this case reconfirms the importance of establishing an appropriate surgical plan based on the detailed preoperative imaging diagnosis.

Conclusion

Knowledge of the anatomy of the cervical fascia is essential for performing ND. This paper presents the intraoperative and imaging findings of ND complicated by deep-seated intermuscular lipoma arising within the prevertebral layer of the deep cervical muscle.

Ethical approval

All procedures performed in this study involving a human participant were in accordance with the ethical standards of our institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Patient consent

Consent was obtained from the patient for the publication of this case report and any accompanying images.