Spindle Cell Lipoma on the Floor of the Mouth

Yalçin M¹, Atilgan SS¹, Laçin N¹, Atalay Y²*

¹Department of Oral and Maxillofacial Surgery, Dicle University, Turkey

²Department of Oral and Maxillofacial Surgery, Afyon Kocatepe University, Turkey

*Corresponding author: Atalay Y, Department of Oral and Maxillofacial Surgery, Afyon Kocatepe University, Faculty of Dentistry, Turkey

Received: March 05, 2015; Accepted: September 10, 2015; Published: September 12, 2015

Abstract

Spindle Cell Lipoma (SCL) is a benign lipomatous histological variant of lipoma which is rarely observed in the oral cavity. It presents as a circumscribed mass in the buccal mucosa, tongue, floor of the mouth or hard palate. In English literature there are nearly 10 case reports of SCL on the mouth floor, all of which were treated with local excision. A case is here presented of intraoral spindle cell lipoma on the floor of the mouth of a 49-year old female. Although oral SCL is rare, it should be considered in the differential diagnosis of lipamatous neoplasms occurring on the mouth floor.

Keywords: Lipoma; Spindle cell lipoma; Oral cavity; Mouth floor

Introduction

Lipomas rarely occur in the oral and maxillofacial region. One kind is the Spindle Cell Lipoma (SCL), which is typically seen as a benign lipomatous neoplasm in the posterior neck and back of older males, and accounts for approximately 1.5% of all lipoma cases [1]. In the oral cavity, the buccal mucosa, tongue, and floor of the mouth are common locations of lipomas [2]. They present as a slow-growing, painless, asymptomatic yellowish, nodular, sub mucosal mass and are covered by normal mucosa. Oral lipomas may cause mastication and speech difficulties [3]. SCL is a distinct histological variant of lipoma derived from prelipoblastic mesenchymal cells [4]. SCL is a rare benign neoplasm, and oral SCL is extremely rare. In this paper, a case is reported of SCL localized to the floor of the mouth in a 49-year old female, and the clinical, histopathological and immune histochemical findings of this case are presented.

Case Presentation

A 49-year old female patient was referred to the Department of Oral and Maxillofacial Surgery with the complaint of swelling on the floor of the mouth, which had been ongoing for 2 years (Figure 1). The patient complained of occasional discomfort while speaking. The growth was gradual in onset, and had slowly increased in size over a period of 2 years to reach its present size. The well circumscribed swelling was not tender on palpation, soft in consistency and mobile. In the intraoral examination, a smooth well-defined sessile nodule of similar color to the surrounding mucosa was detected on the anterior floor of the mouth (Figure 1). It was superficially located and non-infiltrating in front of the sublingual caruncle (opening of the submandibular and sublingual duct) on the floor of the mouth (Figure 1). Based on the history and clinical findings, a provisional diagnosis of lipoma was considered. Excisional biopsy was made under local anesthesia. The yellowish, well-circumscribed soft tissue mass with a lobulated surface 1.5 x 1 x0.5 cm (length x width x thickness) in size was totally excised and sent for microscopic examination in 10% buffered formalin (Figure 2,3,4). In the microscopic examination of H and E stained slides, using a light microscope, a well-circumscribed nodular mass was seen. The histopathology of the soft tissue section showed an encapsulated lesion composed of abundant mature adipocytes arranged in lobules, infrequent blood capillaries, collagen-forming CD34-positive spindle cells and wiry collagen in a variable myxoid background. The lobules were separated by fibrous connective tissue septa. The adipocytes appeared polygonal in shape with clear cytoplasm and the placement of a peripheral flat nucleus that was compressed against the cell membrane (Figure 5A, 5B). Based on clinical and histopathological findings, the swelling was finally diagnosed as SCL. No recurrence has been detected since surgery (Figure 6).

Figure 1: Preoperative clinical situation: Swelling on the floor of the mouth.

    
    
    Figure 1: Preoperative clinical situation: Swelling on the floor of the mouth.

Figure 2: Yellowish, well-circumscribed soft tissue mass.

    
    
    Figure 2: Yellowish, well-circumscribed soft tissue mass.

Figure 3: Surgery site after excision of mass.

    
    
    Figure 3: Surgery site after excision of mass.

Figure 4: Macroscopic examination revealing a nodular lesion.

    
    
    Figure 4: Macroscopic examination revealing a nodular lesion.

Figure 5: A-5B: The histological features revealed fat cells, well vascular network, spindle cells (H&E).

    
    
    Figure 5: A-5B: The histological features revealed fat cells, well vascular
network, spindle cells (H&E).

Discussion

Lipomas usually occur in the shoulders, neck and axilla, whereas this benign tumor is rarely seen in the oral cavity. Intraoral lipomas are rare and statistically constitute approximately 1-4% [4] and SCL constitute approximately 1.5% of all adipose tumors [5]. Intraoral lipomas are benign mesenchymal neoplasms that originate in mature adipose cells with a differential diagnosis of other soft tissue lesions such as mucoceles, dermoid cysts, ranulae, thyroglossal duct cysts, pleomorphic adenomas, angiolipomas, fibrolipomas and malignant lymphomas. In the oral cavity, the buccal mucosa, tongue, and floor of the mouth are the most common locations [5]. Histologically, they can be classified as simple lipoma, fibrolipoma, SCL, intramuscular or infiltrating lipoma, angiolipoma, pleomorphic lipoma, myxoid lipoma and atypical lipoma [3]. The most common site for SCL is the tongue (37%), followed by the cheek/buccal mucosa (31%), and floor of the mouth (15%) but other locations such as the lip, hard palate, alveolar ridge and maxilla have also been reported (Table 1) [6].

Table 1: Features of the 41 spindle cell lipoma reported in the oral cavity.




  
    Author/ Year
       
    Age(years)
    Sex
    Location
    Size (mm)
    Follow-up (Years)
  
  
    Mc Daniel et al. 1984
    33
      52
    F
      M
    Floor of mouth Tongue
    10
    2
      8
  
  
    Christopoulos et al. 1989
    58
    M
    Hard palate
    20
    2
  
  
    Levy & Goding 1989
    74
    F
    Floor of mouth
    45
    --
  
  
    Lombardy & Odell 1994
    68
    F
    Tongue
    15
    --
  
  
    Tosios et al. 1995
    55
    M
    Cheek
    40
    2
  
  
    Khoo & Lian 1995
    23
    M
    Cheek
    50
    --
  
  
    Piatteli et al. 1999
    75
    M
    Cheek
    20
    --
  
  
    Dutt et al. 1999
    42
    F
    Tongue
    30
    --
  
  
    Agoff et al. 2001
    61
    F
    Buccal�    vestibule
     
     
  
  
    Said-Al- Naief et al. 2001
    66
      53
    M
      F
    Tongue
      Tongue
     
     
  
  
    Darling et al. 2002
    69
    M
    Alveolar ridge
    5
    2
  
  
    Atik et al. 2002
    45
    M
    Tongue
    20
     
  
  
    Kaku et al. 2003
    75
    M
    Tongue
    30
     
  
  
    Matsuura et al. 2005
    78
    M
    Tongue
    10
     
  
  
    Piatteli et al. 2005
    50
    M
    Floor of mouth
    10
    3
  
  
    Kawasaki et al. 2006
    42
    F
    Cheek
    50
    --
  
  
    Coimbra et al. 2006
    29
      55
      84
      88
    F
      F
      F
      M
    Floor of mouth
      Lower lip
      Floor of mouth
      Buccal mucosa
    15
      6
      10
      10
    3
       
      1
      2
  
  
    Billings et al. 2006
    55
      84
      88
      45
      67
      31
      75
    F
      F
      M
      M
      M
      F
      F
    Lower lip
      Floor of mouth
      Cheek
      Tongue
      Tongue
      Tongue
      Tongue
    6
      10
      10
      9
      10
      3
      5
     
       
       
      4
      2.25
      1.5
  
  
    Imai et al. 2008
    72
    M
    Tongue
    15
    1
  
  
    Veccio et al. 2009
    72
    M
    Cheek
    25
     
  
  
    Stokes et al. 2011
    35
    M
    Maxilla
    15
    0.7
  
  
    Manor et al. 2011
    23
    M
    Upper lip
    24
    5
  
  
    Caldeira et al. 2011
    38
      60
    M
      M
    Cheek
      Hard palate
    50
      23
     
  
  
    Chandrashekahar et al. 2012
    58
    M
    Buccal mucosa
     
     
  
  
    Manor et al. 2012
    45
      43
    M
      M
    Tongue
      Buccal mucosa
    15
      25
    2
      1
  
  
    Junior et al. 2013
    64
    F
    Tongue
    22
     
  
  
    Abdulaziz Al Sheddi et al. 2014
    68
    M
    Mandibular mucogingival junction
    20
    1
  
  
    Yalçin et al. 2014
    49
    F
    Floor of mouth
    15
    1



Table 1:  Features of the 41 spindle cell lipoma reported in the oral cavity.

SCL is a benign neoplasm and was originally described by Enzinger and Harvey [7]. SCL typically occurs as a painless, slow growing and solitary mass. SCL appears to be well-circumscribed and may demonstrate a thin capsule with a fatty, mucoid or shiny surface, with consistency varying from soft to firm according to the collagen content [8, 9].Microscopic examination showed mature typical fat cells, spindle cells, thick collagen bundles, myxoid interstitial material. The spindle cells are characterized by oval or elongated nuclei and cytoplasm is sparse , poorly defined and eosinophilic [10]. Spindle cells do not react with antibodies to S-100 and factor VIII or to a- smooth actin muscle or desmin. A nerve sheath , endothelial or muscular origin can therefore be eliminated [11, 12]. In contrast, spindle cells show an immunoreactivity to CD34 and vimentin [13]. CD34 is rarely seen in well-differentiated liposarcoma and can prevent the misdiagnosis of SCL as liposarcoma [6]. In contrast to liposarcoma, SCL has a superficial location, a well-defined mass, a uniformity and association of the spindle cells with mature and regular collagen fibers, and no lipoblasts or mitotic (Figure 6). The differential diagnosis of SCL is important because it can easily be misdiagnosed as a malignant lesion such as a liposarcoma. Liposarcoma in sites of easily accessible areas such as the tongue should be classified as atypical lipomas whilst similar tumors arising in inaccessible sites where complete excision of the lesion is difficult to perform should be designated as liposarcoma [14].