|Year : 2014 | Volume
| Issue : 2 | Page : 90-93
Infiltrating lipoma of the chin: Report of a rare case
S. N. Santhosh Kumar, Nandhini Sankaran, Rameshwar Sakharam Dolas, Manju Singh, Sudhanshu Joshi
Department of Oral and Maxillofacial Surgery, Dr. D. Y. Patil Dental College and Hospital, DPU, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||5-Jun-2014|
Department of Oral and Maxillofacial Surgery, Dr. D. Y. Patil Dental College and Hospital, DPU, Pimpri, Pune, Maharashtra
Source of Support: None, Conflict of Interest: None
Lipoma, also known as universal tumor or ubiquitous tumor, can occur anywhere in the body, its incidence being 0.1-5% of all head and neck neoplasms. They are benign neoplasms composed of mature adipocytes. There are various types of lipoma based on the constituent tissue type and location of the lipoma. Though lipomas are slow growing and seldom invade adjacent tissue, some variants do exhibit infiltrative behavior. Here, a case of infiltrating type of lipoma of the chin region is presented, which had suddenly increased size in the last 1 year, which led the patient to seek surgical treatment.
Keywords: Infiltrative lipoma, lipoma, lipoma of chin/face
|How to cite this article:|
Santhosh Kumar SN, Sankaran N, Dolas RS, Singh M, Joshi S. Infiltrating lipoma of the chin: Report of a rare case. J Dent Res Rev 2014;1:90-3
|How to cite this URL:|
Santhosh Kumar SN, Sankaran N, Dolas RS, Singh M, Joshi S. Infiltrating lipoma of the chin: Report of a rare case. J Dent Res Rev [serial online] 2014 [cited 2019 Jan 17];1:90-3. Available from: http://www.jdrr.org/text.asp?2014/1/2/90/133952
| Introduction|| |
Lipoma is a slow growing benign neoplasm, composed of mature adipocytes. They are also called universal or ubiquitous tumors, owing to the extensive literature on lipomas found in almost all locations. , Usually, the patients are asymptomatic (except in cases where there is compression or obstruction). Lipomas are of different types based on the constituent tissue, that is, fibrolipoma, sialolipoma, angiolipoma, myolipoma, hibernoma, etc. Lipomas are metabolically inactive in terms of catabolism during starvation, unlike normal adipose tissue which breaks down during starvation.  The usual presentation is in a subcutaneous location with distinct separation from the surrounding tissues, which can be appreciated by the relatively easy detachment from surrounding tissues during excision. Infiltrative lipoma is a rare type of lipoma, which involves interdigitations within underlying tissue, which is muscle in most of the cases.  This infiltrative nature makes it more prone to recurrence and sometimes causes symptoms like paresthesia, mimicking a liposarcoma clinically. 
| Case Report|| |
A 70-year-old male reported to the Department of Oral and Maxillofacial Surgery, Dr. D. Y. Patil Dental College and Hospital, Pimpri, Pune, with the complaint of a painless swelling on the right side of the chin since past 15 years, which had further grown rapidly in the last 1 year. Patient had no associated symptoms of weight loss, fever, paresthesia, or pain. There was no history of trauma to that region.
Extraoral examination revealed an oval shaped mass on the right lateral chin region roughly measuring 5 cm × 3 cm in its greatest dimension. It was of normal skin color, with normal skin appendages. There were no secondary changes seen [Figure 1], [Figure 2], [Figure 3]. On palpation, it was soft, skin over the swelling was pinchable and slipping sign was positive. However, when the patient was asked to contract his mentalis and platysma muscles, there was slight restriction of mobility of the swelling. No abnormalities were seen on intraoral examination.
Ultrasonography revealed ill-defined regions of altered echogenicity similar to subcutaneous fat. Underlying mandibular cortex was intact. Features were suggestive of lipoma/fibrolipoma, and fine-needle aspiration cytology (FNAC) correlation was suggested. However, FNAC was not done as the patient didn't consent for the same. A provisional diagnosis of lipoma was made and excision of the lesion was planned under local anesthesia.
The lesion was excised through submandibular approach under local anesthesia with intravenous sedation. A horizontal incision was placed along the inferior aspect of the swelling, and the mass of adipose tissue was identified and exposed by blunt dissection [Figure 4]. It was noted that the mass was poorly capsulated and there was considerable attachment of the lesion to the underlying muscle fibers. It was excised along with the attached muscle fibers [Figure 5] and [Figure 6]. The excised specimen measured roughly 6 cm × 5 cm in its greatest dimension [Figure 7]. The excess skin was trimmed, and wound closure was done with polypropylene sutures [Figure 8]. On follow-up, healing was satisfactory with an esthetically acceptable scar [Figure 9].
Histopathological examination revealed lobules of mature adipocytes separated by connective tissue septa, giving the diagnosis of lipoma. Considering the attachment of the lesion to the muscle fibers and poor encapsulation, another histopathological examination was requested of the deeper portion of the lesion. This section showed the presence of strands of nonatrophied muscle tissue interdigitating between the adipose tissue [Figure 10]. No cellular atypia was seen. Based on these features, this lesion was classified as an infiltrating type of lipoma.
|Figure 10: Histopathological section showing muscle fibres interspersed between adipose tissue|
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| Discussion|| |
Lipomas are commonly occurring tumors, with incidence of 0.1-5% of all neoplasms of the head and neck.  Most of the lipomas are considered to be developmental defects, but those in the maxillofacial region arise later in life and are therefore are considered as neoplasms. Infiltrating lipoma is a rare neoplasm that characteristically infiltrates adjacent tissues and tends to recur after excision. Locations at the limbs is the more frequent, with 50% of cases located in the thigh, 20% in the shoulder region and upper arm, 20% in the chest wall, and 10% in other locations.  This type of lipoma is extremely rare in the head and neck region, and its congenital type is rare. ,, The first two cases of oral infiltrating lipoma were reported by Bennhoff and Wood in 1978.  Lipomas with intramuscular invasion tend to recur when they are not adequately resected. They can rapidly enlarge causing local infiltration and require adequate resection, preserving important structures. Some cases of maxillofacial infiltrating lipomas have been reported literature. ,,,,,,,,,,, Many of them involve the glandular structures, and quite a number of cases are of intraoral location, mostly the tongue. 
Most cases of orofacial lipomas are <3 cm × 3 cm, whereas this case it was approximately 5 cm × 5 cm. Usually, infiltrating lipomas exhibit slower growing pattern,  unlike this case where there was an increase in size in 1 year after a long dormant period. They tend to present in the middle age usually;  however, in this case, the patient was 70 years old. However, the very existence of an entity called infiltrative lipoma is still contradicted by the theory of the possibility of entrapment of muscle fibers within the lipoma. However, its infiltrative nature suggests that it is more prone to recurrence, and hence it is advisable to excise the lesion with adequate clearance and maintain periodic follow-ups to check the possibility of recurrence. Some cases of well-differentiated liposarcoma may clinically mimic this lesion, therefore immunostaining with MDM2 and CDK4 markers may be done in aggressive and recurrent lesions. 
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]