Liposarcoma of the tongue: case report and review of the literature.

Abstract

Liposarcoma is the most common soft-tissue malignancy in adults, but the appearance of a liposarcoma in the head and neck region is distinctly unusual. Intraoral liposarcomas represent a particularly interesting subset of this tumor in that (1) they are exceedingly rare and (2) affected patients tend to have a better prognosis than do patients with a similar lesion located elsewhere in the head and neck. An understanding of the histologic subtypes and corresponding clinical behavior of liposarcomas will assist physicians in appropriately managing these patients. Most of these tumors can be effectively treated with conservative surgery. We report the rare case of a well-differentiated liposarcoma arising in the tongue of a 55-year-old man. We also discuss the typical pathologic findings in these malignancies and review the diagnosis, associated controversies, management, and prognosis.

Introduction

Liposarcomas are among the most common malignant mesenchymal tumors in adults, accounting for 9.8 to 21% of all soft-tissue sarcomas. (1-6) The incidence of liposarcoma peaks in the fifth through seventh decades of life. This tumor demonstrates a modest male predominance, in contrast to the female preponderance exhibited by its benign counterpart, the lipoma. (2,3,7) Liposarcomas have a strong predilection for the retroperitoneum and the extremities, which makes the diagnosis and treatment of this malignancy by an otolaryngologist genuinely unusual. (3,4.8-12) In some large series, 4 to 9% of liposarcomas involved the head and neck region. (12)

Intraoral involvement is rare, having occurred in fewer than 0.3% of all liposarcomas reviewed at the Armed Forces Institute of Pathology; overall, fewer than 50 cases of intraoral liposarcoma have been reported in the English-language literature. (1-4,9-14) Most intraoral liposarcomas have been located in the cheek, floor of the mouth, and tongue. (2,3,13) Larson et al reported the first case of a liposarcoma of the tongue in 1976. (15) Since then, a few additional cases involving the tongue have been added to the medical literature, expanding our understanding of the diagnosis and management of this unusual malignancy. (1-3,5,6,10,13,16-18) In this article, we report a new case of glossal liposarcoma.

Case report

A 55-year-old man was referred to our otolaryngology service for evaluation of a painless oral tongue mass that had progressively enlarged over the previous 2 years. The patient denied dysgeusia, bleeding, dysphagia, difficulty with articulation, and paresthesias of the tongue.

On examination, a firm, yellow, 3 x 2-cm mass was seen partially extruding through the overlying mucosa of the left lateral oral tongue (figure 1, A). An excisional biopsy under local anesthesia was performed in the clinic. The entire mass was dissected from the deep muscle of the tongue (figure 1, B). Our pathology department identified the mass as a well-differentiated liposarcoma, and this diagnosis was subsequently confirmed by the Armed Forces Institute of Pathology (figure 2).

[FIGURES 1-2 OMITTED]

Despite our ardent efforts to persuade this patient of the importance of resecting a wider margin at the biopsy site, he has thus far refused to return for further follow-up.

Discussion

The pathologic description of liposarcoma is attributed to Virchow, who first reported this malignant fatty tumor in 1857. (6) The gross appearance of these neoplasms varies; some are firm, well-circumscribed, yellow masses that resemble the familiar lipoma, while others are tan or pink gelatinous tumors. The identification of gross features alone is a wholly unreliable means of differentiating between benign and malignant fatty neoplasms. (1-3)

The definitive diagnosis of liposarcoma is based solely on histopathologic findings on light microscopy. Liposarcomas are classified into four distinct histologic types: well-differentiated, myxoid, round-cell, and pleomorphic. (2,9,13) Well-differentiated liposarcomas (WDLs), which represent 45% of all liposarcomas, are further classified into four histologic subtypes--adipocytic (lipoma-like), sclerosing, inflammatory, and spindle-cell--based on light microscopy features. (19) Adipocytic WDLs are the most common of the four subtypes. Our patient had an adipocytic WDL; on microscopic examination, his tumor clearly demonstrated the classic histopathologic characteristics of liposarcomas: variably sized mature adipocytes, widened fibrous septa, lipocytic atypia and, most important, lipoblasts with multivacuolated cytoplasm and scalloped nuclei (figure 2). (2,3,6,13)

The classification of liposarcomas has important implications for biologic behavior and patient prognosis. The well-differentiated and myxoid types are associated with uniformly good outcomes, including lower recurrence rates (30 to 50%) and excellent survival (75 to 100% at 5 yr); also, these two types do not metastasize unless they undergo dedifferentiation to a high-grade liposarcoma, which is a rare, time-dependent process most often associated with incompletely treated and multiply recurrent liposarcomas. (2,6,9,14,17-19) In contrast, patients with the round-cell and pleomorphic types experience recurrence rates in excess of 80% and distant metastases, and their 5-year survival is as low as 20%. (2,9,14,17-19)

The prognosis for patients with liposarcoma can be correlated not only with histology but also with the site of origin and the size of the tumor at presentation. Regardless of the type of liposarcoma, the prognosis for patients with a tumor of the oral cavity or major salivary gland is better than the prognosis for patients with a liposarcoma in any other head and neck location, especially when the length of the tumor's maximum dimension is less than 5 cm. (2,13) WDLs of the retroperitoneum, larynx, pharynx, and deep musculature of the neck are associated with more frequent and aggressive local recurrences and a higher incidence of distant metastasis than are more superficially located tumors of the same histologic type. (3,9,19,20)

Recognition of clinical behavior differences between readily approachable WDLs and histologically identical lesions that are less surgically accessible has encouraged some authors to assign different names to these malignancies based on their site of origin. However, the taxonomy of WDLs has become a source of some confusion and considerable debate between pathologists and surgeons. Tumors meeting the classic histopathologic criteria for WDLs that arise in the oral cavity, salivary glands, and other superficial, surgically accessible areas are called atypical lipomatous tumors (ALTs). Deeply seated and inaccessible masses of the mediastinum, retroperitoneum, cervical muscles, pharynx, and larynx are called well-differentiated liposarcomas. (3,4,6,9,19,20) This convention of differentiating between WDLs and ALTs serves to recognize the remarkably tractable nature of surgically accessible lesions and helps prevent overly aggressive treatment for a sarcoma that has virtually no potential for metastasis and is otherwise responsive to conservative measures. (9,19,20) Most pathologists consider WDLs and ALTs to be identical on the basis of histologic patterns and karyotypic findings. (19) WDLs and ALTs are morphologically indistinguishable on light microscopy, and they have identical cytogenetic abnormalities (e.g., an extra ring and/or giant marker chromosomes) resulting from amplification of the q13-q15 region of chromosome 12. (4,19,21) Moreover, surgeons generally do not differentiate between WDLs and ALTs when recommending treatment strategies.

The current consensus favors wide local excision of WDLs/ALTs; ideally, tumor-free margins should extend at least 2 cm from the malignancy. (6,9,10,12-14,16,18) Adjuvant radiation therapy can be considered for those patients in whom it was difficult to achieve adequate tumor-free margins or in whom palliation of unresectable disease is appropriate. (1,5,6,12,14,16,17) Routine neck dissections are not warranted because regional metastasis does not occur in patients with WDL/ALT. (1,5,6,16) Currently, chemotherapy has no role in the management of WDL/ALT. (9,14,16)

The combination of modest tumor dimensions, ready surgical access, and the predominance of the well-differentiated histologic type leads to a generally better prognosis for patients with liposarcoma of the tongue or oral cavity than for patients with a liposarcoma arising elsewhere in the head and neck. (1,2,9,13,14,17)

Acknowledgment

The authors thank Robert D. Foss, DDS, MS, chairman of the Department of Oral and Maxillofacial Pathology at the Armed Forces Institute of Pathology, who reviewed the pathology slides and confirmed the diagnosis of a WDL of the tongue.

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Robert Todd Adelson, MD; Robert J. DeFatta, MD, PhD; D.J. Verret, MD; Yuenan Shen, MD

From the Department of Otolaryngology, University of Florida College of Medicine, Gainesville (Dr. Adelson); the Department of Otolaryngology--Head and Neck Surgery (Dr. DeFatta and Dr. Verret); and the Department of Pathology, University of Texas Southwestern Medical Center at Dallas, and the Department of Pathology, VA Medical Center, Dallas (Dr. Shen).

Reprint requests: Robert Todd Adelson, MD, PO Box 100624, Gainesville, FL 32610. Phone: [phone]; fax: [phone]; e-mail: robert.adelson#ent.ufl.edu