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Year : 2019  |  Volume : 8  |  Issue : 4  |  Page : 285-287

Cytological diagnosis of an intramuscular lipoma located on the tongue

Department of Pathology, Sonoscan Healthcare, Malda, West Bengal, India

Date of Submission03-Dec-2018
Date of Acceptance13-Sep-2019
Date of Web Publication15-Oct-2019

Correspondence Address:
Dr. Krishnendu Mondal
C/O- Barendra Nath Mondal, Fularhat, P.O. and P.S. Sonarpur, South 24 Parganas - 700 150, West Bengal
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijhas.IJHAS_99_18

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An intramuscular lipoma (IML) usually arises within the large muscles of extremities. Intraoral examples of this tumor are uncommon. On histopathology, these are characteristically recognized from the diffuse infiltration of muscle fascicles by sweeps of adipocytic proliferation. Classic cytomorphology of the neoplasm has also been described, but are mostly encountered from the extremities. This latest report here explores the utility of fine-needle aspiration cytology in the diagnosis of an IML from one of its unusual locales at the tongue.

Keywords: Adipocytes, fine-needle aspiration cytology, intramuscular lipoma, tongue

How to cite this article:
Mondal K, Mandal R. Cytological diagnosis of an intramuscular lipoma located on the tongue. Int J Health Allied Sci 2019;8:285-7

How to cite this URL:
Mondal K, Mandal R. Cytological diagnosis of an intramuscular lipoma located on the tongue. Int J Health Allied Sci [serial online] 2019 [cited 2022 May 22];8:285-7. Available from: https://www.ijhas.in/text.asp?2019/8/4/285/269256

  Introduction Top

Within oral cavity, the lipomas generally arise from the submucosal adipose tissue of buccal surface, tongue, lips, floor of mouth, palate, and gingiva. They represent about 1%–4% of all intraoral benign neoplasms.[1],[2] Overall, the tongue is affected with only 0.3% cases of lipomas.[3] Intramuscular lipomas (IMLs) are furthermore rare comprising a mere 3%–7% of all intraoral lipomas, and the lingual IMLs have been spotted by a handful number of literatures only.[1],[2] Cytologically, IMLs are mostly encountered from its usual locations at thigh and trunk.[1],[4] However, an IML on the tongue diagnosed by fine-needle aspiration cytology (FNAC) has been an extremely rare experience. In this report, we highlight the cytological and corroborative histological features of one such IML from the tongue of a 68-year-old woman.

  Case Report Top

A 68-year-old female attended the oral surgery outpatient clinic with a gradually enlarging, painless, soft, and globular mass located on the left border of her tongue [Figure 1]. It measured about 4 cm × 3 cm in size, with an intact glistening mucosal covering. The tumor was primarily sampled with FNAC. On the smears, it expressed multiple fragments of mature adipose tissue with interspersed and peripherally adhered fragments of skeletal muscle fibers. Classic muscle giant cells were not detected. The background appeared clear with few lipid droplets only [Figure 2]a and [Figure 2]b. From such an overall cytomorphology, the tumor was diagnosed as IML.
Figure 1: Clinical appearance of intramuscular lipoma on the tongue: Globular mass covered by intact mucosa

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Figure 2: Intramuscular lipoma under microscope: Cytologically, abundance of skeletal muscle fragments intermingle as well as adhere with the adipocytic fragments (a: Papanicolaou stain, ×40, b: Papanicolaou stain, ×100). Histologically, diffuse sheets of adipocytes with trapped muscle fibers lookalike to a checkerboard (c: H and Eosin, ×40), on magnification the lipocytes exclusively appear mature without any atypia, and the muscle fibers lack either degenerative or regenerative changes (d: H and Eosin, ×100)

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The mass was then resected and examined under histopathology. Grossly, the tumor appeared circumscribed with a homogeneous yellowish cut surface. Any focus of necrosis or hemorrhage was not obvious on serial sections. Under microscope, it exhibited confluent sheets of mature adipocytes with several entrapped fibers of skeletal muscles likened to the checkerboard-like appearance [Figure 2]c and d]. Any sort of dyskaryosis, mitossis, necrosis, overt vascularization, or lipoblasts was absent. Hence, the histopathology resurrected the cytological diagnosis of IML. The patient was last examined on her 12 months' follow-up without any recurrence.

  Discussion Top

IMLs generally arise within the major muscles of thigh, shoulder, and arm. Sporadic reports have also described the invasion of paraspinal muscles, chest wall, distal extremities, and short muscles of the head and neck region.[1],[5] The tongue becomes the most common site of head and neck region to get involved with IMLs. Other rare head-neck sites include the cheek, nose, masseter muscle, temporalis muscle, orbicularis oculi muscle, and extraocular muscles.[6]

Histologically, the IMLs demonstrate diffuse infiltration of the muscle fibers by univacuolated mature adipocytes in a haphazard manner. Often the muscle fascicles are entirely outgrown by the adipocytes, only to persist as trapped individual fibers within sheets of adipose tissue. The adipocytic nuclei are located peripherally compressed against the cell membrane and bear homogeneous fine chromatin without any hyperchromasia or irregularities. Individual muscle fibers appear unaltered or sometimes atrophied. Intervening capillary channels are usually sparse.[1],[5] FNAC from the tumor expresses large adipocytic fragments and bits of muscle fibers arrayed in an intimately intermingled fashion. Atrophic muscle fibers or regenerating muscle giant cells can also be seen occasionally.[4] Smears from the currently reported tumor were deficient of any atrophied or regenerating muscle fibers. However, the characteristic juxtaposition of bimodal adipocytic and muscular components zeroed onto the diagnosis of an IML. Finally, on histopathology also, the tumor was affirmed as a typical IML.

Occasionally, the aspirates from subcutaneous lipoma may contain contaminant muscular fragments from deeper soft tissue. However, unlike the IML, these colluding muscle fibers are less in amount and also miss the interlacement with adipose tissue.[4] Sometimes, the vicinal musculature of a long-standing intramuscular hemangioma atrophies into adipocytes. FNAC from such a tumor can also masquerade an IML. In general, a representative sample from the hemangioma yields ample blood components as well as the vascular fragments. However, rare examples still remain elusive, necessitating histopathological confirmation.[4],[5] Well-differentiated liposarcoma is the principal differential consideration for IML on biopsy specimens. A vigilant pursuit for multivacuolated atypical lipoblasts, anaplastic stromal spindle cells, background inflammatory infiltrate, augmented vascularity, and myxoid zones easily discriminate the liposarcoma.[3],[7] Theoretically, skeletal muscles altered by any degenerative myopathy also manifest fatty changes and therefore may cause confusion with IMLs. However, these myopathies are simply ruled out on clinical grounds from the differentials.[5] To distinguish from so many diagnostic mimickers, the tumoral mass of the reported case was meticulously examined through frequent serial sections. Every part therein favored the diagnosis of an IML, and any other lipid-laden lesion was thus excluded.

Conclusively, this latest report states that IML, being an uncommon tumor of the tongue, is quite amenable to be confused with many other lingual lesions. Careful clinical examination and its characteristic cytomorphology are usually sufficient to diagnose it as an IML. Under rare circumstances only, like any other lipomatous lesions, it gets confused with well-differentiated liposarcoma, and then attentive examination of the serial histological sections proves contributory.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Weiss SW, Goldblum JR. Benign lipomatous tumors. In: Schmitt W, editor. Enzinger and Weiss' Soft Tissue Tumors. 5th ed. Philadelphia: Mosby Elsevier; 2008. p. 429-76.  Back to cited text no. 1
Manor E, Sion-Vardy N, Joshua BZ, Bodner L. Oral lipoma: Analysis of 58 new cases and review of the literature. Ann Diagn Pathol 2011;15:257-61.  Back to cited text no. 2
Murthy SS, Rao ST, Patnaik SC. Intramuscular lipoma of the tongue: A rare site for a common tumour. Case Rep Clin Pathol 2014;1:22-6.  Back to cited text no. 3
Akerman M, Domanski HA. The cytological features of soft tissue tumours in fine needle aspiration smears classified according to histotype. In: Orell SR, editor. The Cytology of Soft Tissue Tumours. Basel: Karger; 2003. p. 17-34.  Back to cited text no. 4
McTighe S, Chernev I. Intramuscular lipoma: A review of the literature. Orthop Rev (Pavia) 2014;6:5618.  Back to cited text no. 5
Sferopoulos NK. Anatomical distribution of intramuscular lipomas. J Forensic Sci Res 2017;1:35-9.  Back to cited text no. 6
Han HH, Choi JY, Seo BF, Moon SH, Oh DY, Ahn ST, et al. Treatment for intramuscular lipoma frequently confused with sarcoma: A 6-year restrospective study and literature review. Biomed Res Int 2014;2014:867689.  Back to cited text no. 7


  [Figure 1], [Figure 2]

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