Discussion
Liposarcoma (LS), the tumor of embryonic mesenchymal origin, is the most common soft tissue sarcomas (STSs), comprising 15% of all STSs. The usual site of presentation of this tumor is retroperitoneal (45%), followed by all extremities (24%). (1) However, it is uncommon to see it in the head and neck region, particularly in the oral cavity. In the review of 23 cases of LS of the oral cavity, the tongue was the preferred site with an incidence of 52%, whereas LS occurred in the buccal mucosa in 39% of cases, in another series of 18 cases of LS of the oral cavity and salivary glands. (2)
As per WHO 2020, LS is classified into four subtypes based on morphology, viz. 1. Well-differentiated liposarcoma (WDLS)/ Atypical lipomatous tumor (ALT), 2.Dedifferentiated liposarcoma (DDLS), 3.Myxoidliposarcoma (MLS), and 4.Pleomorphic liposarcoma (PLS).(3) 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. (4)
Well-differentiated liposarcoma (WDLS), also known as Atypicallipomatous tumor (ALT), is the most common variant accounting for about 40%-45% of all LA with the peak age of occurrence between 40-60 years. (5) Though the oral cavity, specifically the tongue, rarely gets involved by LS, often it is WDLS when there is involvement (75% of the cases). (2) As per Moritani et al., only 33 cases of WDLS/ALT were recorded globally from 1976 to 2008. (6) The condition often presents as a slowly growing painless mass without bleeding, dysphagia, dysgeusia, difficulty in articulation, and paraesthesia of the tongue. On examination, the lesion mainly presents as a firm or soft, elastic, nodular, and movable yellow-tan mass with variation in size depending upon the time of presentation. (2,6–9) Though the lesion is limited to submucosal at the time of presentation, as in our case, the cases with mucosal extrusion have also been reported. (6,7) Lymph nodes are typically not palpable, although neighboring lymph nodes were palpable in the case of Nunes et al. (10)
A lipoma with regressive alterations and an intramuscular lipomais among the differential diagnoses for WDLS of the tongue. It was the initial diagnosis in the cases of Moritani et al. and Allon et al. (6,8) Other conditions that should be considered in the differential diagnosis are amyloidosis, myxoma, myxosarcoma, benign fat tumors (hibernoma), angiolipoma, fibrolipoma, pseudosarcomatous fasciitis, and malignant histiocytoma. (8,10) Amyloidosis was a pre-operative clinical diagnosis in the study of Allon et al., whereas preliminary diagnosis in the study of Dubin et al. (8,11) Due to the broad spectrum of differential diagnosis, detailed histopathological examination is essential for a definite diagnosis.
The new World Health Organization categorization splits WDLS into three subclasses based on their morphologic characteristics: adipocytic, sclerosing, and inflammatory. Despite discovering three histologic variations, these subclasses have little clinical significance. (1) The tumor is yellow-tan, lobulated, and often covered by intact mucosa, giving them the appearance of a lipoma. (2) 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. (6) It presents with limited nuclear atypia and few or no lipoblasts. (12)Lipoblasts, when present, are vacuolar, multinucleated, or have highly stained nuclei. (6) It’s vital to note that the existence of lipoblasts does neither guarantee nor exclude a diagnosis of liposarcoma. (13)
Immunohistological markers add to the diagnosis of liposarcoma. WDLS exhibits vimentin, S100, MDM-2, Ki-67, and CDK4 positivity. However, the positivity for the spindle cell component of WDLS is still under dispute. (2,8) The genes that code for all of these proteins are found on chromosome 12q13–15. These DNA sequences make up the majority of the supernumerary ring and giant rod chromosomes, which are the cytogenetic hallmarks of ALTs in around 93% of instances.
The treatment of choice for WDLS is wide surgical excision. Lymph node dissection depends upon the state of metastasis. 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. (11) Transformation of WDLS to dedifferentiated type increases the chance of metastasis. (12) Hence, adequate margin coverage and close observation after surgery are crucial in WDLS.
Conclusion:
Though well-differentiated liposarcoma 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 recurrence of WDLS. Similarly, regular follow-up is pre-vital as there is a chance of recurrence despite it being rare.