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Early View Article: Online published version of an accepted article before publication in the
final form.
Journal Name: Journal of Case Reports and Images in Pathology
Type of Article: Case Report
Title: Chondroid Lipoma: A Rare Recently Described Benign Lipomatous Tumor (Case
Report)
Authors: Salman T. Al-Malki, Abdullah S. Al-Khamiss
doi: To be assigned
Early view version published: July 14 , 2015
How to cite the article: Al-Malki S.T, Al-Khamiss A.S. Chondroid Lipoma: A Rare Recently
Described Benign Lipomatous Tumor (Case Report). Journal of Case Reports and Images
in Pathology, Forthcoming 2015.
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TYPE OF ARTICLE: Case Report 1
2
TITLE: Chondroid Lipoma: A Rare Recently Described Benign Lipomatous Tumor 3
(Case Report) 4
5
AUTHORS: 6
Salman T. Al-Malki1, MD , Abdullah S. Al-Khamiss2, MD 7
8
AFFILIATIONS: 9
1Department of Pathology, King Fahad Medical City, Riyadh, Saudi Arabia 10
2Department of Pathology, King Fahad Medical City, Riyadh, Saudi Arabia 11
12
CORRESPONDING AUTHOR DETAILS 13
Abdullah Saleh Al-Khamiss, Department of Pathology, King Fahad Medical City, Al-14
Olaya, Khurais road, Riyadh city, Riyadh region, Kingdom of Saudi Arabia. 15
Phone: 00966-506-13-9201 16
E-mail: [email protected] 17
18
Guarantor of Submission : The corresponding author is the guarantor of 19
submission. 20
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TITLE: Chondroid Lipoma: A Rare Recently Described Benign Lipomatous Tumor 21
(Case Report) 22
23
ABSTRACT 24
25
INTRODUCTION 26
lipomatous tumors group is a group of tumors containing both benign and malignant 27
neoplasm, that sometimes have some morphological overlapping. Chondroid lipoma 28
is one of the rare benign lipomatous tumors that have been described recently. 29
Although it is benign in nature, its microscopic picture is mimicking some of the 30
malignant tumors, especially myxoid liposarcoma. CASE REPORT: A 51-year-old 31
lady presented with a mass arising in her right thigh. This mass grew slowly during 32
the several months ago. Radiologically, it was described as a well-circumscribed 33
benign mass with scanty fatty component. Surgical excision and primary closure was 34
performed for the patient. Histopathologic examination demonstrated a well-35
circumscribed mass formed by cords and nests of lipoblasts and lipocytes embedded 36
in a prominent myxoid to hyalinized chondroid matrix. A panel of 37
immunohistochemical (IHC) stains had been done. From the clinical, radiological, 38
and pathological information, the diagnosis of chondroid lipoma was made. 39
CONCLUSION: This case is considered a rare variant of lipoma and easily can be 40
misdiagnosed as myxoid liposarcoma or extra-skeletal myxoid chondrosarcoma. So, 41
the pathologist should be aware of this entity when he/she comes across such 42
cases. 43
44
Keywords: Lipoma, Chondroid lipoma, Myxoid liposarcoma, Extra-skeletal 45
chondrosarcoma. 46
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TITLE: Chondroid Lipoma: A Rare Recently Described Benign Lipomatous Tumor 47
(Case Report) 48
49
INTRODUCTION 50
Lipomatous tumors have a broad clinical and morphological spectrum ranging from 51
benign cases to malignant ones. Myxoid liposarcoma is the second most common 52
type of liposarcoma. It represents 30% of liposarcomatous tumors in general. Mostly, 53
it arising in the thigh of 30-40 years age group patients in both sex equally. It has the 54
tendency to recur and metastasis distally. In the last few years, a rare variant of 55
benign lipomatous tumors have been described, called "chondroid lipoma". Although 56
this variant is benign in nature, it histopathological morphology make it one of the 57
great mimicker of many malignant soft tissue tumors, especially myxoid liposarcoma. 58
59
CASE REPORT 60
51-years-old female patient is presenting to the OPD with a right thigh swelling. This 61
swelling starts to appear several months ago. It is painless but slowly progressive. 62
There is no decrease in weight or loss of appetite. 63
On physical examination, there is a non-tender mass in the upper part of the right 64
thigh. This mass is firm, deeply-seated, roughly oval, and not pulsated or fixed to the 65
skin. CBC, LFT, RFT, and minerals (Na+, K+, & Ca+2) are all within normal limits. 66
The radiological examination shows well-defined mass contain only a small amount 67
of fatty tissue distributed centrally & peripherally (Figure 1). The mass have been 68
excised and the gross picture shows a circumscribed lobulated tan-yellowish mass 69
measuring 5.2 x 4.3 x 3.8 cm (Figure 2). 70
Microscopically, the mass is well-circumscribed and formed by lobules separated by 71
fibrous septa. Each lobule is formed by nests and cords of cells embedded in a 72
chondroid-myxoid background (Figure 3). The cells have variable morphology: some 73
of them are mature adipocytes with single large intracytoplasmic vacuole, others 74
have multi-vacuolated cytoplasm resembling lipoblasts (Figure 4 and 5). 75
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Some of the cells have a pericytoplasmic clear zone (lacunae-like), making it 76
resembling chondrocytes (Figure 5). Mild nuclear pleomorphism and rare scattered 77
mitoses are noted (Figure 6). No chicken-wire blood vessels seen in the background. 78
IHC stains shows that the tumor cells are positive for vimentin (Figure 7) & S100 79
(Figure 8) and negative for CK, EMA, CD34, SMA, desmin, & HMB45. 80
Based on the previous findings, a diagnosis of chondroid lipoma is made. The 81
patient had been discharged with a follow-up appointment. 82
83
DISCUSSION 84
Lipomatous tumors are one of the most common soft tissue tumors that usually 85
diagnosed by the pathologists. They have a wide range of morphological and 86
behavioral spectrum from benign things (lipoma) to malignant one (liposarcoma) [1-87
2]. Chondroid lipoma is a very rare variant of lipomatous tumors [1,3]. It had been 88
firstly described by Meis and Enzinger in 1993 [4]. They describe it as a lipoma 89
contains two histological components: a) adipose tissue (containing mature fat cells 90
& lipoblasts), and b) cartilaginous tissue (containing chondroblasts & hyaline matrix) 91
[4]. Now, according to the World Health Organization (WHO) 2002, chondroid lipoma 92
is defined as “a unique & recently recognized benign adipose tissue tumor containing 93
lipoblasts, mature fat cells, and chondroid matrix" [3]. Why this tumor occurs? still 94
unknown, but there are two hypothesis regarding to the origin of the cartilaginous 95
component of this tumor: a) it represents a metaplastic changes in an ordinary 96
lipoma due to a mechanical stress, and b) it arising from the multipotential stem cells 97
under the influence of some growth factors that are present in this lesion [3,5]. 98
Regarding to the age group, usually this type of tumor will affect adult people in their 99
third and fourth decades [3,6] but it can arise in pediatric age group also [7]. It arise 100
more in females [3,6]. Proximal extremities and limb girdles are the most common 101
affected sites, however, trunk and head & neck areas can be affected too [3]. It 102
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presented as a painless, slowly growing, superficial or deeply seated soft tissue 103
mass [3,6]. 104
Grossly, it is a well-circumscribed lobulated tan-yellow mass with a size range of 2-7 105
cm [3,6]. Microscopically, the tumor is a well-circumscribed lobulated mass with 106
lobules separated by fibrous septa [3,6]. Its histological hallmarks are nests and 107
cords of abundant uni- and multi-vacuolated lipoblasts embedded in a prominent 108
myxoid to hyalinized chondroid matrix admixed with a variable amount of mature 109
adipose tissue [3]. Lipocytes are also present [3,6]. NO/mild pleomorphism and rare 110
mitosis are accepted [3,6]. Some small cells with lacunae-like zone are present [3,6]. 111
No chicken-wire blood vessels in the background but some scattered thick wall blood 112
vessels are noticed [3,6]. The cells contain both glycogen and lipid which highlighted 113
by PAS and oil-red O stains, respectively [1,3,6]. Reticulin stain shows that there is a 114
pericellular reticulin fibers [1-3,6]. Immunohistochemically, the cells are positive for 115
S100, vimentin, CD68, and rarely for CK [1,3,6]. They are negative for EMA, HMB45, 116
SMA, MSA, GFAP, and CD57 [1,3,6]. Ki67 proliferation index is less than 1% [3]. 117
Cytogenetically, some of chondroid lipomas have t(11;16) which resulting in C11 or 118
f95-MKL2 fusion oncogene [2-3,6]. How this fusion will lead to the formation of this 119
tumor? Still no clear answer. 120
The differential diagnosis of chondroid lipoma includes benign and malignant tumors 121
[1-3,6,8-9]. Myxoid liposarcoma is one of the most mimickers for chondroid lipoma 122
but it can be differentiated by its infiltrative pattern, the presence of chicken-wire 123
blood vessels, and the presence of t(12;16) or t(12;22) which will lead to the fusion of 124
DDIT3 with FUS or EWS1 genes, respectively [2-3,6]. Myxoid chondrosarcoma is 125
another mimickers for chondroid lipoma but it can be differentiated by its infiltrative 126
pattern, absence of the cytoplasmic vacuoles, absence of the fatty components, and 127
the presence of chromosomal translocation that causing fusion of NR4A3 in 128
chromosome-9 [2-3,6]. Spindle cell lipoma is one of the differential diagnosis of 129
chondroid lipoma but it have ropey collagen fibers, lack of chondroid background, 130
has diffusely expressed CD34 in 131
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the spindle cell component, and a deletion involving chromosomes 13q and 16q [2-132
3,6]. 133
It is important to know this type of benign tumor to avoid misdiagnosing it as a 134
sarcoma and the subsequent overtreatment of the patients with radical surgery, 135
chemotherapy, and radiotherapy [1-4,6,8,10-11]. Chondroid lipoma will be cured with 136
simple excision [3]. It will not recur or metastasis [3]. 137
138
CONCLUSION 139
Chondroid lipoma is a rare variant of lipoma with histomorphological features that 140
mimic myxoid liposarcoma and extra-skeletal myxoid chondrosarcoma. Attention 141
should be paid from the pathologist when he/she evaluates such cases, particularly 142
on core biopsy sample. 143
144
CONFLICT OF INTEREST 145
The authors declare that there is no conflict of interests regarding the publication of 146
this article. 147
148
AUTHOR’S CONTRIBUTIONS 149
Salman T. Al-Malki - Conception and design, Acquisition of data, Analysis and 150
interpretation of data, Drafting the article, Critical revision of the article, Final 151
approval of the version to be published. 152
Abdullah S. Al-Khamiss - Conception and design, Acquisition of data, Analysis and 153
interpretation of data, Drafting the article, Critical revision of the article, Final 154
approval of the version to be published. 155
156
ACKNOWLEDGEMENTS 157
Nothing 158
159
REFERENCES 160
1. Gokhale U, Pillai GR, Varghese PV, Samarsinghe D. Chondroid lipoma: a 161
case report. Oman Medical Journal 2008; Volume 23, Issue 2, April 2008. 162
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2. De Vreeze R, Van Coevorden F, Boerrigter L, Nederlof PM, Haas RL, Bras J, 163
et al. Research article delineation of chondroid lipoma: an 164
immunohistochemical and molecular biological analysis. Hindawi Publishing 165
Corporation Sarcoma 2011; Volume 2011, Article ID 638403: 5 pages. 166
3. Fletcher C.D.M., Unni K.K., Mertens F. (Eds.): World Health Organization 167
(WHO) Classification of Tumours. Pathology and Genetics of Tumours of Soft 168
Tissue and Bone. IARC Press: Lyon 2002. 169
4. Meis JM, Enzinger FM. Chondroid lipoma. A unique tumor simulating 170
liposarcoma and myxoid chondrosarcoma. Am J SurgPathol 1993 171
Nov;17(11):1103-1112. 172
5. Hwang HS, Lee WJ, Lim HK, Chun HK, Ahn GH. Chondrolipoma in the pelvic 173
cavity: a case report. Korean J Radiol 2008;9:563-567. 174
6. Thway K, Flora RS, Fisher C. Review article chondroid lipoma: an update and 175
review. Annals of Diagnostic Pathology 2012;16:230-234. 176
7. Kindblom LG. Lipomatous tumors-how we have reached our present views, 177
what controversies remain and why we still face diagnostic problems: a tribute 178
to Dr Franz Enzinger. AdvAnatPathol 2006 Nov;13(6):279-285. 179
8. Gomez-Ortega JM, Rodilla IG, De Lerma JM. Chondroid lipoma a newly 180
described lesion that may be mistaken for malignancy. Oral Surgery, Oral 181
Medicine, Oral Pathology and Oral Radiology 1996 May; Volume 18, Issue 182
5:586-589. 183
9. Lakshmiah SR, Scott KW, Whear NM, Monoghan A. Chondroid lipoma: a rare 184
but diagnostically important lesion. International Journal of Oral and 185
Maxillofacial Surgery 2000 December; Volume 29, Issue 6:445-446. 186
10. Nielsen GP, O’Connell JX, Dickersin GR, Rosenberg AE.Chondroid lipoma, a 187
tumor of white fat cells.A brief report of two cases with ultrastructural analysis. 188
Am J SurgPathol 1995 Nov;19(11):1272-1276. 189
11. Mentzel T, Remmler K, Katenkamp D. Chondroid lipoma. Clinicopathological, 190
immunohistochemical, and ultrastructural analysis of six cases of a distinct 191
entity in the spectrum of lipomas.Pathologe 1999 Nov;20(6):330-334. 192
193
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FIGURE LEGENDS 194
Figure 1: Radiological picture showing thigh with deep-seated well-circumscribed 195
mass. 196
Figure 2: Gross picture showing a circumscribed tan-yellow lobulated mass. 197
Figure 3: Low-power view demonstrates that the lesion has lobular pattern with a 198
myxoid background (H&E x40). 199
Figure 4: Intermediate-power view shows mature fat cells with degenerative changes 200
and the surrounding chondromyxoid matrix (H&E x200). 201
Figure 5: High-power view showing mature fat cells and lipoblasts embedded in a 202
chondroid matrix. Some lacunae-like cells are also present (H&E x400). 203
Figure 6: High-power view showing many lipoblasts with mild nuclear pleomorphism 204
embedded in a chondroid matrix (H&E x400). 205
Figure 7: The cells are diffusely positive for vimentin (immunohistochemistry stain 206
x200). 207
Figure 8: The cells are focally positive for S100 (immunohistochemistry stain x200). 208
FIGURE 209
210
211
Figure 1: Radiological picture showing thigh with deep-seated well-circumscribed 212
mass. 213
214
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215
Figure 2: Gross picture showing a circumscribed tan-yellow lobulated mass. 216
217
218
Figure 3: Low-power view demonstrates that the lesion has lobular pattern with a 219
myxoid background (H&E x40). 220
221
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222
Figure 4: Intermediat-power view shows mature fat cells with degenerative changes 223
and the surrounding chondromyxoid matrix. (H&E x200). 224
225
226
Figure 5: High-power veiow showing mature fat cells and lipoblasts embedded in a 227
chondroid matrix. Some lacunae-like cells are also present (H&E x400). 228
229
230
231
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232
233
Figure 6: High-power veiow showing many lipoblasts with mild nuclear pleomorphism 234
embedded in a chondroid matrix .(H&E x400). 235
236
237
238
239
Figure 7: The cells are diffusely positive for vimentin (immunohistochemistry stain 240
x200). 241
242
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243
244
Figure 8: The cells are focally positive for S100 (immunohistochemistry stain x200). 245
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