INTRODUCTION
Liposarcoma (LS) is one of the most common soft tissue sarcomas that arise from embryonic mesenchymal tissue. These sarcomas commonly arise at retroperitoneal locations and extremities. The incidence of LS peaks in the 5th–7th decades of life.[1]
LS has a modest male predominance, in contrast to the female preponderance exhibited by its benign counterpart, the lipoma.[2] The appearance of LS in the head and neck region is extremely rare. In the head and neck region, the commonest site of presentation is neck (28%), followed by the larynx (20%) and pharynx (18%) Oral LSs have been reported mainly in the buccal mucosa, with other sites including the floor of the mouth, tongue, palate, and mandible. Oral LSs are extremely rare, with the tongue as a preferred site. But the affected patients tend to have a better prognosis than do patients with a similar lesion located elsewhere in the head and neck.[3] LS is divided into four subtypes: atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDLS), myxoid LS (MLS), pleomorphic LS (PLS), and dedifferentiated LS (DDLS). ALT/WDL is categorized as intermediate (locally aggressive) adipocytic tumors and is the most common subtype of LS, making up 30–40% of all LSs.[4] In the oral region, ALT/WDL and MLS are the predominant subtypes. These tumors have a tendency of local recurrence, but distant metastasis rarely occurs unless these tumors become dedifferentiated.[5] We report the rare case of a WDLS arising in the tongue of a 55- year-old man.
CASE REPORT
A 55-year-old male presented to our outpatient department with complaints of swelling on the right lateral border of tongue. On examination, the swelling was nontender, immobile, and firm. On MRI face T1/T2, a well-defined hyperintense nonenhancing lesion in right lateral margin of tongue was identified. On MRI, impression of lipoma was given and wide local excision of the lesion was planned [Figure 1a].
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Figure 1: (a) Axial T1-weighted images show a small well-defined bright lesion along the right lateral border which shows loss of signal on T1 fat-saturated image (arrow). (b) High-power view demonstrating multiple lipoblasts in fibrous stroma. Note pleomorphic, hyperchromatic nuclei (hematoxylin and eosin, 40×). (c) Tumor cells show cytoplasmic and nuclear staining for S100. (d and e) Tumor cells exhibit nuclear positivity for MDM2 and CDK4, respectively. (f) Tumor cells exhibit focal positivity for p16
On gross examination, a well-circumscribed, grey-white nodular structure of size 2 × 1.5 × 1.2 cm3 was received. Cut section was fibrofatty. Under microscopy, the sections showed a well-circumscribed tumor composed of lobules of mature adipocytes separated by fibrous strands. The adipocytes are of variable size, intermingled between are seen few spindle cells having hyperchromatic nuclei and moderate amount of cytoplasm [Figure 1b]. However, no necrosis/mitosis/myxoid areas were seen. Further evaluation by immunohistochemistry showed immunopositivity for CDK4, MDM2, S100, and P16 (focally) [Figure 1c-f] favoring the diagnosis of WDLS. All the margins are free of tumor. The patient is on follow-up and has no local recurrence.
DISCUSSION
LSs of oral cavity and salivary gland area are rare. However, LS is one of the most common soft tissue sarcomas which is embryonic mesenchymal in origin and its usual sites of presentation are followed by all extremities.[4,6]
LSs in the head and neck region are rare, particularly in the oral cavity. In a study review of 23 cases of LS of the oral cavity, the tongue was the preferred site with an incidence of 52%. In another similar study of a series of 18 cases of LS, buccal mucosa was the preferred site with an incidence of 39%.[5,7,8]
As per WHO 2020, LS is classified into four subtypes based on morphology: (1) WDLS/ALT, (2) DDLS, (3) MLS, and (4) PLS. Different LS variants have varied aggressive potentials because of their morphologic diversity. DDLS, high-grade MLS, and PLS all show a high propensity for metastasis, but WDLS does not metastasize without dedifferentiation, and MLS has a more indolent clinical behavior and a reduced metastatic potential.[7-9]
WDLS is the most common variant (40–45%) among these, with the peak age of occurrence between 40 and 60 years. Oral cavity, specifically the tongue, rarely gets involved by LS, and most common type in this location is WDLS (75% of the cases).[8,9] WDLS often presents as a slowly growing painless mass without bleeding, dysphagia, dysgeusia, difficulty in articulation, and paresthesia of the tongue. On examination, the lesion mainly presents as a firm or soft, nodular, and movable yellow-tan mass with variation in size depending upon the time of presentation. Lymph nodes are typically not palpable.[7,9,10]
Grossly, LS is yellow-tan, lobulated, and often covered by intact mucosa, giving them the appearance of a lipoma. But, in contrast to the lipoma, WDLS is made up of a relatively mature adipocytic proliferation in which significant variation in cell size is easily discernible and is admixed with fibrous connective tissues. Here, adipocyte nuclei are heavily stained in discrete areas, and unusual multinucleated stromal cells are frequently seen. It presents with limited nuclear atypia and few or no lipoblasts.[3,4,6,10] Lipoblasts, when present, are vacuolar, multinucleated, or have highly stained nuclei. It is vital to note the existence of lipoblasts, although it neither guarantees nor excludes a diagnosis of LS.[7-9]
Immunohistochemistry markers add to the diagnosis of LS. WDLS exhibits vimentin, S100, MDM-2, Ki-67, and CDK4 positivity. The treatment of choice for WDLS is wide surgical excision. The tumor-free margins should extend at least 2 cm from the malignancy. Lymph node dissection depends upon the state of metastasis. Adjuvant radiation therapy can be considered for those patients in whom it was difficult to achieve adequate tumor-free margins. Currently, chemotherapy has no role in the management of WDLS/ALT. Though the prognostic value of tumor size is unclear, adequate margin excision has great prognostic importance as the recurrence rate can increase from 17% to 80% due to incomplete removal of the tumor. Transformation of WDLS to dedifferentiated type increases the chance of metastasis. Hence, adequate margin coverage and close observation after surgery are crucial in WDLS.[8-10]
CONCLUSION
Though WDLS of the tongue is rare, it should always be on the list of differential diagnoses of tongue lesions. Resecting adequate margin is crucial during the surgical intervention as margin positivity has a high predilection for the recurrence of WDLS. Similarly, regular follow-up is prevital as there is a chance of recurrence despite it being rare.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
REFERENCES
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