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© 1998 The Journal of Bone and Joint Surgery, Inc. Nuchal Fibroma of the Shoulder Involving Skeletal Muscle: A Radiographic and Clinicopathological Study. A Case Report* , NEWARK, NEW JERSEYInvestigation performed at the Departments of Pathology, Orthopaedic Surgery, and Radiology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark
Nuchal fibromas are rare superficial lesions involving the skin and subcutaneous tissue of the neck. Clinically and radiographically, they may resemble more invasive lesions such as dermatofibrosarcoma protuberans and fibromatosis (extra-abdominal desmoid tumor), which usually involve the skin and the subcutaneous tissue, or they may resemble synovial sarcoma, which involves the deep tissue. We report the case of a patient who had a nuchal fibroma that involved skeletal muscle and peripheral nerves.
An athletic fifteen-year-old boy was noted to have a large painless mass over the left shoulder during a routine physical examination. The mass had been present for at least one year, and the patient had no history of trauma. Additional examination revealed a poorly defined, rubbery mass, measuring fifteen by ten centimeters, that displaced the scapula posteriorly and inferiorily. There was no evidence of scoliosis and no history of neuromuscular disease. The remainder of the history and physical examination was unremarkable. Standard radiographs of the shoulder and scapula did not reveal any osseous involvement but confirmed the presence of a soft-tissue mass (Fig. 1).
Magnetic resonance imaging of the shoulder and scapula revealed a septated mass along the posterolateral aspect of the left part of the thorax; the mass demonstrated low signal intensity on T1-weighted, T2-weighted, and contrast-enhanced sequences. The lesion was located between the scapula and the muscles of the chest wall, and it had infiltrated the subscapularis, trapezius, and latissimus dorsi muscles (Fig. 2). There was no evidence of neurological or vascular involvement. The age of the patient as well as the findings on magnetic resonance imaging suggested that the mass was a desmoid tumor or some other fibrous lesion. Other neoplasms such as elastofibroma also were considered.
A Tru-cut (Baxter Health Care, Deerfield, Illinois) needle biopsy revealed a dense and virtually acellular fragment of collagenous tissue. Staining was negative for elastic fibers. On the basis of the pronounced hypocellularity of this small biopsy specimen, a diagnosis of nuchal fibroma was made. The options of operative resection and observation were discussed with the patient and his family, who decided to proceed with operative treatment with the understanding that the preservation of neurovascular function would be of paramount importance. Two months after the biopsy, the lesion was resected. At the time of the operation, a posterior incision was made from the acromioclavicular joint to the inferior angle of the scapula. The mass was found to have infiltrated the deep layers of the lateral portion of the trapezius, the rhomboid major and minor, and the cephalad portion of the latissimus dorsi. To facilitate examination of the undersurface of the mass, the inferior angle of the scapula was elevated from the chest wall by transection of the fibers of the serratus anterior. Starting from the most caudad aspect of the lesion, portions of the latissimus dorsi, the rhomboids, the trapezius, and the medial aspect of the subscapularis were resected along with the main body of the tumor. After separation of the mass from the undersurface of the scapula, the most cephalad aspect of the tumor was found to be adherent to the brachial plexus. The tumor was transected across its most cephalad aspect, parallel to the superior trunk of the brachial plexus; the lateral cord was left in situ. Histological analysis of frozen sections confirmed the diagnosis of nuchal fibroma. No neurological deficits were noted postoperatively.
The resected pale-gray mass weighed 490 grams and measured 16.5 by 15.0 by 6.5 centimeters (Fig. 3). It appeared to be unencapsulated and had no distinct border. Multiple sections of the lesion revealed dense, markedly hypocellular fibrous tissues entrapping muscle fibers and small peripheral nerves (Fig. 4). The elastic stain was negative, and the trichrome stain demonstrated the fibrous nature of the lesion. Immunohistochemical staining was positive for vimentin, negative for smooth-muscle actin, and negative for S-100 protein. The diagnosis of nuchal fibroma was confirmed on the basis of the location and the pronounced hypocellularity of the lesion.
In young people, the most common soft-tissue tumors are hemangiomas, lymphangiomas, lipomas, and fibromatoses2. Overtly malignant soft-tissue lesions are uncommon. The diagnosis of fibromatosis is made if cellular lesions composed of myofibroblasts are found to be infiltrating adjacent areas, with indistinct borders between the lesions and the surrounding tissue. Most of these lesions are treated with operative excision and radiation therapy4. Other fibrous lesions, such as nuchal fibromas, are rare but may mimic more invasive lesions; however, wide resection of a nuchal fibroma is not necessary. Nuchal fibroma, which, to our knowledge, was first described in 1988 by Enzinger and Weiss3, is a rare clinical entity. The most comprehensive review of which we are aware indicates that nuchal fibromas typically are subcutaneous lesions with some dermal involvement. They are superficial to the deep fascia and do not involve muscle or fascia1. These clinical findings contrast with those associated with other fibrous lesions such as desmoid tumors and elastofibromas3, which are found at deeper locations. Our patient was found to have extensive involvement of skeletal muscle and fascia as well as peripheral nerve entrapment. To our knowledge, we are the first to report the case of a patient who had a nuchal fibroma that involved deep skeletal muscle and major nerves of the upper limb. Nuchal fibromas usually range from 2.5 to eight centimeters in their largest dimension; however, as the case of our patient demonstrates, these lesions may be much larger at the time of presentation. Morever, although nuchal fibromas usually involve superficial tissues, our findings demonstrate that they also may involve deep skeletal muscle and fascia and may be difficult to resect.
NOTE: The authors thank Sharon Weiss for reviewing this study and Fred. F. Behrens for editing this manuscript.
*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.
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