DOI:10.2214/AJR.07.2529
AJR 2008; 190:40-44
© American Roentgen Ray Society
Enchondroma Protuberans of the Hand
Yeong-Yi An1,
Jee-Young Kim1,
Myeong-Im Ahn1,
Yong-Koo Kang2 and
Hyun-Joo Choi3
1 Department of Radiology, The Catholic University of Korea, St. Vincent's
Hospital, 93 Ji-dong, Paldal-ku, Suwon, Kyunggi-do 442-723, Republic of
Korea.
2 Department of Orthopedic Surgery, The Catholic University of Korea, St.
Vincent's Hospital, Suwon, Kyunggi-do 442-723, Republic of Korea.
3 Department of Pathology, The Catholic University of Korea, St. Vincent's
Hospital, Suwon, Kyunggi-do 442-723, Republic of Korea.
Received May 8, 2007;
accepted after revision June 30, 2007.
Address correspondence to J. Y. Kim
(jeeykim{at}catholic.ac.kr).
FOR YOUR INFORMATION
Unique new customized medical search engine service from ARRS! ARRS
GoldMinerTM is a new keyword- and concept-driven search engine that
provides instant access to radiologic images published in peer-reviewed
journals. For more information, visit
http://goldminer.arrs.org.
Abstract
OBJECTIVE. Enchondroma protuberans is a rare tumor that arises from
an intramedullary enchondroma with an exophytic growth pattern. The purpose of
this study was to describe imaging findings of this disease that were obtained
using both radiography and MRI.
CONCLUSION. It is necessary to understand the characteristic imaging
findings of enchondroma protuberans to avoid misdiagnosis. When radiography
does not allow a clear diagnosis of enchondroma protuberans, MRI may be
helpful for diagnosis.
Keywords: cartilage • enchondroma protuberans • hand • MRI • tumor
Introduction
Enchondroma is a common type of tumor of the hand that occurs on its
own or as part of Ollier's disease. Enchondroma protuberans usually develops
in the phalanges or metacarpal bones
[1-4],
although it has also been reported in the ribs and humerus
[2-6].
In general, enchondroma protuberans describes a lesion that protrudes outward
from one side of an affected bone and radiographically mimics an
osteochondroma or chondrosarcoma
[6,
7]. Although enchondroma
protuberans is a type of enchondroma, it produces images that differ from
those of enchondroma. The purpose of this study was to report the imaging
findings of four cases of enchondroma protuberans of the hand.
Materials and Methods
Patients
Our study group was composed of a retrospective collection of four patients
with enchondroma protuberans that was confirmed pathologically and
radiologically between March 2005 and January 2006 at our institution. The
group consisted of two males and two females (age range, 11-52 years; median
age, 28 years). In all patients, the leading symptom was the presence of a
palpable mass in the hand.
Imaging
Patients underwent radiography and MRI. MRI was performed with a 1.5-T
scanner (TwinSpeed, GE Healthcare) using the wrist-array coil. Images were
obtained in the axial, sagittal, or coronal planes and included T1-weighted
spin-echo (TR/TE, 366/13), T2-weighted spin-echo (TR range/TE range,
3,000-4,000/84-87), fat-saturated T2-weighted fast spin-echo
(3,000-4,000/79-87), and contrast-enhanced T1-weighted spin-echo (366/13)
sequences. The contrast-enhanced T1-weighted images were obtained after IV
administration of gadopentetate dimeglumine (0.1 mmol/kg of body weight).
Slice thickness varied from 2 to 3 mm for all sequences. The field of view was
10 cm, and the matrix was 256 x 256.
Radiography was used to analyze the pattern and location of the bone
lesion, tumor matrix calcification, and the change of cortex. Secondary
changes in the surrounding structures were also evaluated. The signal
intensity and enhancement pattern of each lesion and associated imaging
findings in the surrounding structures were analyzed using MRI.
Results
The radiologic patterns of four patients with enchondroma protuberans are
summarized in Table 1. One
lesion was located in the metacarpal bone, two lesions were located in the
proximal phalanges, and one was located in the distal phalanx.
On radiography, all cases showed geographic osteolytic lesions in the
intramedullary cavity. These lesions occurred eccentrically in two cases and
centrally in the other two cases. The first two patients showed exophytic
protruding masses through a focal cortical defect that extended from the
intramedullary lesions (Figs.
1A and
2A). The first patient also
showed a few stippled calcifications in the tumor, suggesting chondroid
calcifications (Fig. 1A). The
second patient showed remodeling of the adjacent cortex as a result of a
juxtacortical protruding mass as well as a discontinuous rim calcification and
internal stippled calcification in the protruded mass
(Fig. 2A). The third patient
showed cortical ballooning as a result of an eccentric osteolytic lesion that
had a focal cortical defect and stippled calcification in the adjacent soft
tissue (Fig. 3A). The fourth
patient had a central intramedullary osteolytic lesion and another soft-tissue
mass with stippled tumor matrix calcification and thin rim calcification in
the adjacent soft tissue. In the fourth patient, no cortical defect was
detected on radiography (Fig.
4A).
View larger version (79K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —14-year-old girl with enchondroma protuberans. Radiograph shows
exophytic protruding mass with geographic osteolytic lesion, which has
stippled calcifications in fifth metacarpal bone. Focal cortical defect is
seen in proximal portion and cortical ballooning is seen in distal portion of
lesion. Note cortical thickening in diaphysis of fourth metacarpal bone.
|
|
View larger version (97K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A —11-year-old boy with enchondroma protuberans. Radiograph shows
juxtacortical mass with stippled and rim calcifications in proximal phalanx of
right index finger. Cortex is remodeled and there is small geographic
osteolytic lesion (thick arrow) in medullary cavity. Another small
geographic osteolytic lesion is located eccentrically in middle phalanx
(thin arrow).
|
|
View larger version (50K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A —52-year-old woman with enchondroma protuberans. Radiograph shows
eccentric geographic osteolytic lesion (arrow) with cortical
ballooning in distal phalanx of fifth finger. Focal cortical defect and
stippled calcifications are seen in adjacent soft tissue.
|
|
View larger version (97K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A —34-year-old man with enchondroma protuberans. Radiograph shows ovoid
soft-tissue mass with stippled tumor matrix calcifications and rim
calcification in volar side of proximal phalanx of fifth finger. There is
central geographic osteolytic lesion, which erodes cortex, resulting in
endosteal scalloping and cortical thinning.
|
|
View larger version (82K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B —14-year-old girl with enchondroma protuberans. Coronal
fat-suppressed fast spin-echo T2-weighted MR image shows hyperintense mass
with hypointense septa. There is peritumoral edema in adjacent bone marrow
(arrows) and soft tissue.
|
|
MR images showed well-defined intramedullary masses extending exophytically
through the cortical defect in all cases. T1-weighted images were hypointense
in all cases (Fig. 4B),
although only a few very small hyperintense dots were present in one patient.
The masses were found to be hyperintense on the spin-echo and fat-saturated
fast spin-echo T2-weighted images (Figs.
1B,
2B,
3B, and
4C). Spin-echo and
fat-saturated spin-echo T2-weighted images also revealed low-intensity septa
and nodules within the masses in three patients, suggesting that chondroid
calcification had occured within the tumor matrix.
View larger version (53K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B —34-year-old man with enchondroma protuberans. Sagittal spin-echo
T1-weighted MR image shows hypointense masses in intramedullary cavity and
adjacent soft tissue, which are connected through cortical defect.
|
|
View larger version (119K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B —11-year-old boy with enchondroma protuberans. Coronal fat-suppressed
fast spin-echo T2-weighted MR image shows hyperintense mass with low-intensity
nodules and septa (thick arrow). Another small hyperintense mass is
noted in middle phalanx (thin arrow).
|
|
View larger version (117K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B —52-year-old woman with enchondroma protuberans. Coronal
fat-suppressed fast spin-echo T2-weighted MR image shows separate hyperintense
masses (arrow) in intramedullary cavity and juxtacortical area that
are connected through cortical defect.
|
|
The gadolinium-enhanced image showed nodular and thick wall enhancement in
three patients (Fig. 4D) and
heterogeneous enhancement in one patient
(Fig. 3C). The MR images
clearly revealed the connection of the intramedullary and outward-protruding
portions of the tumors through a focal cortical defect in all cases. The
outward-protruding portions of the tumors were encircled by a thin rim of low
intensity on the T1- and T2-weighted images. In addition, two cases showed
associated imaging findings in the surrounding structure, including a thick
periosteal reaction in the adjacent metacarpal bone and soft-tissue edema and
a thickened nail bed. Another case showed an additional intramedullary
enchondroma in the adjacent phalanx. All patients underwent surgery and were
discharged without any complications. All cases were confirmed as enchondroma
on pathologic examination.
View larger version (38K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C —52-year-old woman with enchondroma protuberans. Contrast-enhanced
axial fat-suppressed T1-weighted MR images show inhomogeneous enhancement in
both lesions (arrows). Adjacent nail bed is thickened
(arrow, D).
|
|
Discussion
Enchondroma is a common benign cartilaginous tumor. Thirty-five percent of
enchondromas arise in the hand. Histologically, an enchondroma originates from
groups of chondrocytes in the growth plates and then forms extending columns
of uncalcified cartilage under the growth plates. This growth can then be
walled off and proliferate further to form an intraosseous chondroma.
Radiologically, a single enchondroma appears as a well-defined, geographic
osteolytic lesion that is usually centrally located within the metadiaphysis.
The cortex remains intact, although it may be thinner because of endosteal
scalloping and expansion. Stippled or punctate matrix calcification is found
scattered randomly through the radiolucent defect in 50% of cases
[1,
6,
7].
Enchondromas can expand through the cortex, becoming enchondroma
protuberans; however, this rarely occurs. Enchondroma protuberans is a rare
benign chondromatous tumor that arises in the medullary canal, forming an
exophytic mass in the surrounding soft tissue. Because of the location,
enchondroma protuberans is defined as an exophytic enchondroma of the long
bones. The presence of an exophytic mass distinguishes enchondroma protuberans
from conventional enchondroma
[4]. Radiographs of enchondroma
protuberans typically show a well-defined geographic, osteolytic
intramedullary lesion that may have poorly defined matriceal calcification
combined with a cortical defect and well-defined round soft-tissue expansion
[2].
Although enchondroma protuberans can usually be diagnosed using only
radiographs, two of the cases we encountered could not be positively diagnosed
using radiography alone because it did not reveal the protruded mass or the
cortical defect. The MR images clearly delineated the connection between the
intramedullary lesion and the exophytic protrusion through the cortical defect
as well as the tumors themselves, which resulted in the diagnosis of
enchondroma protuberans. Although radiography is a better imaging technique
than MRI for the detection of chondroid calcification in the tumor matrix, MRI
has the advantage of revealing associated findings in the surrounding tissues
in addition to the tumors themselves. Enchondroma protuberans should be
considered in the differential diagnosis of osteochondroma, chondrosarcoma,
and periosteal chondroid tumors.
Radiologically, enchondroma protuberans closely resembles osteochondroma;
however, osteochondroma can be excluded on the basis of the absence of a
cartilage cap with underlying trabecular bone. Enchondroma protuberans also
has a geographic intramedullary osteolytic lesion, as was seen in all of our
cases [1,
2,
3,
6]. It is important to
distinguish between osteochondroma and enchondroma protuberans when planning
surgical treatment to prevent potential chondrosarcomatous transformation. In
the case of classic osteochondromas, the regions containing cartilage are
generally confined to the cap. Therefore, excision of the cap alone is
sufficient. In the case of enchondroma protuberans, however, deposits of
cartilage are found not only within the protruded tumor mass but also within
the adjacent underlying medulla of the host bone. Thus enchondroma protuberans
should be treated by a combination of resection of the cartilage containing
protuberans and intramedullary curettage
[7].
View larger version (37K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3D —52-year-old woman with enchondroma protuberans. Contrast-enhanced
axial fat-suppressed T1-weighted MR images show inhomogeneous enhancement in
both lesions (arrows). Adjacent nail bed is thickened
(arrow, D).
|
|
View larger version (103K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4E —34-year-old man with enchondroma protuberans. Photomicrograph shows
benign cartilaginous tissue protruding (white arrows) beyond confines
of normal cortex (stars). Tumor is covered by thin fibrous connective
tissue (black arrow). (H and E, x30)
|
|
Periosteal chondroid tumors, including periosteal chondroma or periosteal
chondrosarcoma, produce an appearance similar to enchondroma protuberans. The
radiographic appearance of periosteal chondroma is usually typical. The lesion
develops subperiosteally and erodes the underlying cortex, forming a sclerotic
and saucer-shaped base; however, the endosteal surface may remain intact or
the medullary bone may be partially invaded
[8,
9]. In cases of periosteal
chondroma, it appears as if cortical destruction was caused by invasion of the
juxtacortical mass from the outside. Conversely, enchondroma protuberans
results in an outward bulging contour of the cortex, reflecting the expansion
of the intramedullary lesion.
Enchondroma protuberans has been mistaken for chondrosarcoma, particularly
in the ribs. Although the occurrence of chondrosarcoma in the hand is rare, it
is the most common primary malignant bone tumor of the hand. Radiologically,
both lesions have similar features, such as focal cortical defect and adjacent
soft-tissue mass formation. Therefore, an incisional biopsy before definitive
resection should be performed
[2]. Although enchondroma
protuberans showed soft-tissue extension through the cortical defect in all of
our cases, a complete thin periosteal shell with low intensity was observed on
MRI, suggesting that benign tumors were present. Two cases in our study were
associated with changes in the surrounding tissues. To our knowledge, such
changes have not been previously reported. These associated findings were
caused by a pressure effect exerted by the protruded tumor mass.
In conclusion, although enchondroma protuberans is a type of enchondroma,
the imaging findings it produces are quite different from other types.
Enchondroma protuberans can radiographically resemble other tumors, such as
osteochondroma or periosteal chondroid tumors. Knowing the characteristic
imaging findings of enchondroma protuberans can prevent misdiagnosis. When the
diagnosis of enchondroma protuberans is uncertain on the basis of radiographic
findings, MRI may help make the correct diagnosis.
References
- Degreef I, De Smet L. Enchondroma protuberans of the phalanx.
Scand J Plast Reconstr Surg Hand Surg2005; 39:315
-317[CrossRef][Medline]
- Dagum AB, Sampson SP. Enchondroma protuberans: a case report.
J Hand Surg [Am] 1998;23
: 338-341[CrossRef][Medline]
- Kita K, Masada K, Yasuda M, Takeuchi E. Enchondroma protuberans of
the phalanx: a case report. J Hand Surg [Am]2003; 28:1052
-1054[CrossRef][Medline]
- Slesarenko YA, Sampson SP, Gould ES, Dagum AB. Recurrent
enchondroma protuberans: a case report. J Hand Surg
[Am] 2005; 30:1318
-1321[CrossRef][Medline]
- Keating RB, Wright PW, Staple TW. Enchondroma protuberans of the
rib. Skeletal Radiol 1985;13
: 55-58[CrossRef][Medline]
- Caballes RL. Enchondroma protuberans masquerading as
osteochondroma. Hum Pathol 1982;13
: 734-739[Medline]
- Crim JR, Mirra JM. Enchondroma protuberans: report of a case and
its distinction from chondrosarcoma and osteochondroma adjacent to an
enchondroma. Skeletal Radiol 1990;19
: 431-434[Medline]
- Vanel D, De Paolis M, Monti C, Mercuri M, Picci P. Radiological
features of 24 periosteal chondrosarcomas. Skeletal
Radiol 2001; 30:208
-212[CrossRef][Medline]
- Robinson P, White LM, Sundaram M, et al. Periosteal chondroid
tumors: radiologic evaluation with pathologic correlation.
AJR 2001; 177:1183
-1188[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Abstract
Introduction
