# Extraskeletal Chondroma of the Preauricular Region: A Case Report and Literature Review

Authors: Futoshi Watanabe; Tadahiko Saiki; Yoshihisa Ochochi
Journal: Case Reports in Medicine
 (2012)

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## Abstract

An extraskeletal chondroma is a rare benign cartilaginous tumor that develops in soft tissue. Histologically, it is a lobulated nodule surrounded by a fibrous capsule; the inside consists of mature hyaline cartilage containing a few normal chondrocytes. We present a rare case of extraskeletal chondroma in the preauricular region. A 43-year-old man presented with a 2-cm-diameter right preauricular tumor that had been developing for 1 year. Magnetic resonance imaging showed a solid lobulated tumor in the right preauricular region, which was proximate to the capsule of the right temporomandibular joint (TMJ). This was subsequently resected under general anesthesia. The tumor was not in contact with the TMJ capsule and had not invaded the surrounding tissue, facilitatingen bloc excision. Histopathologically, the tumor comprised mainly of hyaline cartilage containing chondrocytes with chondrocytic lacunae and was diagnosed as a chondroma. The postoperative period was uneventful, and there was no evidence of recurrence at the 2-year followup. We describe the clinical characteristics of our case and review the literature, emphasizing the differential diagnosis.


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## Body

## 1. Introduction

Extraskeletal or soft-tissue  chondromas  are  rare  benign  cartilaginous  tumors  that  develop  in  soft tissues without  bone or  joint  involvement,  occurring  predominantly  in the  hands  and  feet  of  adults   in  their  third  and  fourth  decades  of  life [1, 2].  In  the  head  and  neck,  extraskeletal  chondromas  are  rare,  having  been  described mainly in  the  tongue [3, 4].  To  our  knowledge,  only  one  extraskeletal  chondroma has been reported in the preauricular region [5].  This  paper  describes  an  extremely  rare  extraskeletal  chondroma  that  developed in the preauricular region of a 43-year-old man.


## 2. Case Presentation

A 43-year-old man was referred to our department complaining of a mass in the right preauricular region, which had been developing painlessly over 1 year.  The physical examination revealed a hard mass approximately 2 cm diameter in the right preauricular region.  Otoscopy showed swelling of the anterior wall in the right external acoustic meatus, covered by normal skin.  There was no temporomandibular  joint (TMJ) pain, trismus, or hearing loss, and there was no history of facial trauma.  The general physical examination did not disclose any abnormalities.Magnetic resonance imaging (MRI) revealed a solid lobulated lesion in the right preauricular region, which was proximate to the capsule of the right TMJ (Figure1).  The lesion was isointense relative to muscle on T1-weighted images, hyperintense on T2-weighted images, and partially enhanced after gadolinium injection.T1 gadolinium-enhanced axial (a) and sagittal (b) magnetic resonance images show a solid tumor (arrow) proximate to the capsule of the right temporomandibular joint in the right preauricular region.
(a)
(b)A benign tumor in the right TMJ was suspected clinically.  The lesion was removed surgically via a preauricular incision under general anesthesia to determine the histopathological diagnosis.  The lesion was independent of the parotid gland and was not in contact with either the TMJ or the cartilage of the acoustic meatus (Figure2).  Although the lesion was attached to the surface of the temporal bone, there was no invasion of the temporal bone, and the lesion was removed easily by en blocexcision.Figure 2
Intraoperative image showsen bloc excision of the tumor.The  specimen  was  a  2.5 × 2 × 1.5 cm, well-circumscribed,  nodular, white-grey,  hard, elastic mass.  Histopathologically, the tumor was well circumscribed and encapsulated by thin fibrous connective tissue.  The tumor comprised mainly of hyaline cartilage, which contained chondrocyte  with  chondrocytic  lacunae, with collagenous  fibrous  tissue  in  the  center  of  lesion (Figure3).  The  tumor  had low cellularity, with no evidence of atypia or mitotic figures.  Immunohistochemically, the chondrocytes expressed  S-100 protein  and  vimentin, but  were  negative  for  epithelial  cell  markers.  These  histopathological findings revealed the diagnosis of chondroma.Histopathologically, (a) the tumor consists of hyaline cartilage and collagenous fibrous tissue (H&E stain, ×40).  (b) The hyaline cartilaginous tissue contains homogeneous chondrocytes with round nuclei and chondrocytic lacunae (H&E stain, ×200).
(a)
(b)The  postoperative  period was uneventful, and there  was  no  evidence of  recurrence  at  the 2-year  followup.


## 3. Discussion

Extraskeletal  or  soft-tissue  chondromas  are  rare  benign  cartilaginous  tumors  that  occur  in  tissue  unrelated  to  bone  and are  usually  found  in  close proximity  to  tendons  or  joint  capsules [1, 2].  These  tumors  arise  most  commonly  in  the  hands and  feet  of  middle-aged  adults  and  have  an  equal  sex  distribution.  The  clinical  symptoms  are  usually  related  to  those  of  a  slowly, insidiously  expanding  mass  that  occasionally  causes  tenderness  or pain.  Less  common  locations  include  the chest and  abdominal  wall, lung, fallopian tube, and other visceral organs.  In the head and neck, extraskeletal chondromas are most prevalent in the tongue [3, 4] and  rare  in  the  cheek [6, 7],  parotid  gland [8, 9],  neck [10],  masticatory  space [11],  parapharyngeal  space  [12],  and  masseter  muscle [13].  Our  literature  survey  found  only  one  previous  account of a chondroma  in  the  preauricular  region [5].The  literature  review  of  extraskeletal  chondromas  of  the  parotid  region  is  summarized  in Table1. The  five  cases  of parotid chondroma, including ours,  included  two  in  the  parotid  gland,  two  in  the  preauricular  region,  and  one  in  the  masseter muscle.  Patients  were  three  males  and  two  females.  The  median  patient  age  was  45.0 (range 32–54) years.  The greatest  diameter  of  the  tumor  was  reported  in  four  cases  and  averaged  3.2  (range 2.5–4.0) cm.  Wide  local  excisions  were performed  in  all  cases, and  no  recurrence  was  mentioned  for  cases  for  which  follow-up  data  were  available.Table 1
The literature review of extraskeletal chondromas of the parotid region.
Author (year)
Age
Sex
Duration
Location
Size (cm)
Treatment
Recurrence
Kostpoloulos et al. (1993) [9]
32
M
7 years
Parotid gland
NA
Excision
—
Aslam and Haqqani (2006) [8]
47
F
2 years
Parotid gland
4 × 3 × 2
Excision
—
Vazques Maha et al. (2007) [5]
54
F
4 years
Preauricular region
2.5 × 2.5
Excision
—
Falleti et al. (2009) [13]
49
M
6 years
Masseter muscle
4
Excision
—
Present case
43
M
1 year
Preauricular region
2.5 × 2 × 1.5
Excision
—
TMJ: temporomandibular joint; NA: not available.The  etiology  of  extraskeletal  chondroma  is  uncertain.  In the literature on tongue chondromas, it  is  felt  that  either  these lesions  develop  from residual  embryonal  tissue  in  an  area  of  preexisting  fetal  cartilage  or  pluripotent  mesenchymal  cells undergo  metaplasia,  differentiating  into  cartilage  as  a  result  of  some  irritating  stimulus [3].  However,  the  exact  causal relationship  is  poorly  defined.Histologically,  the  lesion  is  a  lobulated  nodule  surrounded  by  a  fibrous  capsule  filled  with  mature  hyalinized  cartilage tissue, with  no  association  with  underlying  bone.  Locally,  it  may  be  associated  with  secondary  degeneration  within  the matrix,  such  as  cystic  change,  ossification,  calcification,  fibrosis,  and  mucinous  change [1, 2].Radiologically,  extraskeletal  chondromas  are  well-demarcated  extraskeletal  masses  with  a  periarticular  location.  Computed  tomography  (CT)  shows  an  iso- or hyperdense  soft-tissue mass  without  underlying  bone  involvement;  calcifications  are  seen  in 33–70%  of  cases [2].  MRI  shows  a  sharply  delineated  lobulated  mass  with  hypo- to isointense  signals  relative  to  muscle  on  T1-weighted  images,  hyperintense  signals  on  T2-weighted  images,  and  various  patterns  of enhancement  with  contrast  medium [14].  In  our  case,  no  calcifications  were  observed  in  the  histological  specimens, although  no  preoperative  CT  was  obtained.For lesions in the preauricular region, the differential diagnosis includes parotid gland and TMJ tumors, such as osteochondromas  and  synovial chondromatosis.  The  chondromatosis  change  of  a  pleomorphic  adenoma  or  mixed  parotid tumor  can  be  similar  to  that of  a  chondroid  tumor [15].  An  osteochondroma  is  a  cartilage-capped  bony  projection  on  the external  surface  of  bone;  these  usually  occur  in  younger  patients  and  stop  developing  after  adolescence.  Histologically, synovial  chondromatosis  can  be  similar  to  an  extraskeletal  chondroma, but  there  are  multiple  nodules  arising  in  the synovium;  they  are  usually  intra-articular  and  can  involve  bone.  In  our  case,  the  preoperative  diagnosis  was  a  TMJ  tumor because  the  lesion  was  proximate  to  the  TMJ  capsule,  although  it  was not  in  contact  with  the  TMJ,  and  there  was  no evidence  of  surrounding  tissue  invasion.  Histopathologically,  the  lesion  was  mainly  hyaline  cartilage  and  fibrous  tissue without  severe  atypia  or  mitosis  and  was  diagnosed  as  a  chondroma.  Immunohistochemistry  is  useful  because  the  tumor cells  are  positive  for  S-100  protein  and  vimentin  and  negative  for  epithelial  and  myoepithelial  cell  markers [8, 9].It  is  also  important  to  distinguish  chondromas  from  malignant  cartilaginous  neoplasms;  however,  it  may  be  difficult to  distinguish  between  a  chondroma  and  low-grade  chondrosarcoma  histologically.  Some  clinical  features  should  raise  a suspicion of malignancy, including  older  age  at  presentation,  rapid  growth,  and  the  invasion  of  surrounding  structures [2].  Recurrence  or  metastasis  also  helps  with  the  differential  diagnosis.Wide  local  excision  is  recommended  for  treatment  owing  to  the  10–15%  recurrence  rate [1, 2].  In our case, the  tumor was  well  encapsulated  and  excised  completely,  and  there  was  no  evidence  of  recurrence  2  years  postoperatively.  We  plan to  observe  the  patient  for  the  long term  because  of  the  possibility  of  late  tumor recurrence.In conclusion, we present a very rare extraskeletal chondroma of the preauricular region and review the literature on extraskeletal chondromas of the parotid region.



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*Source: 121743-2012-07-10.xml*