Introduction
Chondromyxoid fibroma (CMF) is an exceedingly rare tumor that represents less than
1% of all primary bone neoplasms.[1] First described by Jaffe and Lichtenstein in 1948,[2] CMFs need to be distinguished from other aggressive cartilaginous tumors that have
significantly different treatments and prognoses. CMF is a benign tumor characterized
by lobules of spindle-shaped or stellate cells with abundant myxoid or chondroid intercellular
material with a varying number of multinucleated giant cells of different sizes.[3] Most frequently, it is found in young adults of the second and third decades of
life in the lower extremity long bones, particularly arising from the metaphysis.[4] CMF can also arise in numerous other anatomic sites. Its occurrence in the facial
and cranial bones is extremely rare.
CMF of the cranial bones is an exceedingly challenging diagnosis to make.[5]
[6] Zilmer and Dorfman report an initial misdiagnosis rate of 22% in their series of
36 CMF cases.[7] Depending on its location, CMF can be difficult to distinguish from an aneurysmal
bone cyst, fibrous dysplasia, giant cell tumor, osteoblastoma, osteosarcoma, Ewing
sarcoma, mucocele, Langerhans histiocytosis, or even a schwannoma.[5]
[8]
[9] More often, CMF is mistaken for three other myxoid tumors: chordoma, chondroid chordoma,
and chondrosarcoma that have a greater frequency of occurrence in the craniofacial
skeleton.[10]
[11]
Here we update the total English literature count to 59 cases of CMF arising from
the skull base, including our case of sphenoclival CMF. Additionally, to our knowledge
we report the second case of CMF involving the parietal bone published in an English-language
journal.
Case 1
A 38-year-old right-handed woman presented with a 1.5-year history of nasal obstruction
and serous rhinorrhea. Approximately 1 month prior to her visit, she also noticed
diplopia. A computed tomographic (CT) scan and magnetic resonance imaging (MRI) of
the paranasal sinuses were obtained, which showed an expansile lesion of the central
skull base, in the sphenoclival region, with extension into the left infratemporal
fossa ([Fig. 1]). An endoscopic biopsy of the mass was obtained and an initial diagnosis of a malignant
fibrohistiocytoma was made. On further review, the pathology was interpreted as showing
a “Fibro-mixoid tumor, locally aggressive, and with unknown metastatic potential.”
This patient's case was discussed at our Joint Planning Conference and the recommended
treatment was surgery.
Fig. 1 Case 1. Preoperative axial (B) and coronal (B) CT scans identify this destructive
central skull base mass. There is erosion of the clivus (arrow in A) and of the middle
fossa floor (arrow in B). Preoperative pos-contrast axial T1-weighted MRI (C) and
coronal T2-weighted MRI (D) reveal findings typical for most “chondroid” tumors. Low
signal intensity with homogeneous enhancement on T1-weighted postcontrast imaging
and high signal intensity on T2-weighted imaging. Images (E) and (F) identify residual
disease following the patient first surgery (arrows). Follow-up MRI imaging (G) and
(H) reveal progressive enlargement of the residual tumor (arrows) prompting further
surgical management.
The patient underwent a transmaxillary approach to the anterior cranial fossa with
resection of the extradurally located tumor. Postoperative course was uneventful and
the patient was discharged on postoperative day 4.
On follow-up, the patient reported left facial numbness in the V2 distribution and
postoperative MRI showed residual tumor at the left lateral portion of the pterygopalatine
fissure. The final pathology report was CMF. The minimal residual disease was followed
with serial MR imaging.
Over the ensuing year, the patient's tumor showed slow but progressive growth. Surgical
resection of the progressive residual sphenoclival CMF was performed. She underwent
a left orbitocranial approach to middle cranial fossa with resection of the tumor.
Postoperative course was uneventful and the patient was discharged on postoperative
day 2. She is disease free at 4.5 years.
Case 2
A 31-year-old right-handed woman presented with a 1-year history of brief, mild, left-sided
headache. Approximately 3 months prior to her visit, she noticed a lump and tenderness
over the left parietal area. As the tenderness increased, she ultimately underwent
MR imaging. This revealed the presence of a large lesion centered within the diploe
of the parietal bone. There was no intradural extension. At the time of presentation,
the patient was in her third trimester of pregnancy, so treatment was postponed to
follow her delivery. Subsequent high-resolution CT and MRI images showed a stable
tumor, and the patient elected for surgery ([Fig. 2]).
Fig. 2 Case 2. Preoperative axial postcontrast T1-weighted MRI (A), axial T2-weighted MRI
(B), and coronal postcontrast T1-weighted MRI reveal a large tumor of the parietal
bone with its epicenter in the diploe of the skull. The typical pattern of inhomogeneous
enhancement on T1-weighted imaging and hyperintensity on T2-weighted imaging is again
seen. Preoperative (D) and postoperative (E) axial CT scans reveal complete tumor
removal with custom cranial implant replacing the removed bone.
She underwent resection of the left parietal calvarial lesion and reconstruction with
a custom cranial implant. Postoperative course was uneventful and the patient was
discharged on postoperative day 3. Her pathology report indicated left parietal calvarial
CMF in bone and 3 month follow-up CT showed no evidence of recurrent or residual tumor.
She is disease free at 5.5 years.
Methods
A retrospective literature review was performed. Pubmed search terms included “chondromyxoid
fibroma” with English-language filter. Publication dates were limited to January 1,
1990 to April 21, 2013. Search was secondarily refined by article type, case report,
and tumor location, calvarial and skull base. Skull base tumors were further categorized
into sinonasal, clival/sellar, sphenoid/parasellar, orbit/zygoma, or temporal bone/occiput.
All included articles were analyzed and relevant information extracted for the table.
Tumor locations and clinical symptoms were standardized for [Table 1]. This study was conducted with approval from The University of Texas M. D. Anderson
Cancer Center Institutional Review Board (IRB) under protocol PA14–0505.
Table 1
Reported cases of CMF in the calvarium and skull base
Calvarial (8)
|
Case no.
|
Author
|
Year
|
Age
|
Sex
|
Location
|
Clinical symptoms
|
Treatment
|
Gross total/subtotal resection
|
Radiation
|
Radiation dose
|
Follow-up (mo)
|
Recurrence
|
1
|
Wilson et al
|
1991
|
26
|
F
|
Parietal bone
Squamous temporal bone
|
—
|
Excision
|
—
|
None
|
0
|
—
|
—
|
2
|
Morimura et al
|
1992
|
41
|
M
|
Frontal bone
|
Hand hypesthesia
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
—
|
—
|
3
|
Wu et al
|
1998
|
—
|
—
|
Frontal bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
4
|
Wu et al
|
1998
|
—
|
—
|
Fontal bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
5
|
Wu et al
|
1998
|
—
|
—
|
Fontal bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
6
|
Karkuzhali et al
|
2005
|
11
|
F
|
Parietal bone
|
Convulsions
HA
|
Excision
|
Gross total
|
None
|
0
|
15
|
No
|
7
|
Hakan et al
|
2008
|
45
|
F
|
Frontal bone
|
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
20
|
No
|
8
|
Our study
|
2013
|
31
|
F
|
Parietal bone
|
HA
Tender swelling
|
Excision
|
Gross total
|
None
|
0
|
3
|
No
|
SKULL BASE (59)
|
Sinonasal (17)
|
Case no.
|
Author
|
Year
|
Age
|
Sex
|
Location
|
Clinical symptoms
|
Treatment
|
Gross total/subtotal resection
|
Radiation
|
Radiation dose
|
Follow-up (mo)
|
Recurrence
|
1
|
Koay et al
|
1995
|
57
|
F
|
Ethmoid sinus
Frontal sinus
Nasal bone
Orbit
|
Painless swelling
|
Excision
|
Subtotal
|
None
|
0
|
6
|
No
|
2
|
Isenberg
|
1995
|
34
|
F
|
Ethmoid sinus
Nasal bone
|
Nasal obstruction
Painless swelling
|
Excision
|
(1) Subtotal (2) Gross total
|
None
|
0
|
(1) 36 (2) 8
|
Yes
|
3
|
Nazeer et al
|
1996
|
New born
|
M
|
Ethmoid sinus
|
Apnea
Nasal obstruction
Cardiorespiratory arrest
|
Excision
|
Gross total
|
None
|
0
|
12
|
No
|
4
|
Mendoza et al
|
1998
|
New born
|
M
|
Ethmoid bone
Nasal bone
|
Nasal obstruction
|
Excision
|
Gross total
|
None
|
0
|
24
|
No
|
5
|
Wu et al
|
1998
|
—
|
—
|
Ethmoid bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
6
|
Shek et al
|
1999
|
6
|
F
|
Ethmoid sinus
Frontal bone
Maxillary bone
Nasal cavity
Sella turcica
|
Blindness, Epistaxis
Nasal obstruction
|
Curettage x4
|
Subtotal x4
|
+
|
50 Gy
|
120
|
Yes x3
|
7
|
Wang et al
|
2000
|
60
|
F
|
Ethmoid bone
Nasal bone
|
Asymptomatic
|
Excision
|
Gross total
|
None
|
0
|
6
|
No
|
8
|
Baujat et al
|
2001
|
50
|
F
|
Ethmoid sinus
Frontal sinus
Nasal bone
|
HA
Nasal obstruction
Nasal pain
|
Excision
|
Gross total
|
None
|
0
|
18
|
No
|
9
|
Azorin et al
|
2003
|
46
|
M
|
Frontal sinus
|
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
22
|
No
|
10
|
Smith et al
|
2006
|
49
|
F
|
Nasal cavity
Palate
|
—
|
Biopsy
|
Gross total
|
None
|
0
|
30
|
No
|
11
|
Veras et al
|
2009
|
60
|
F
|
Nasal cavity
|
Asymptomatic
|
Excision
|
Gross total
|
None
|
0
|
12
|
No
|
12
|
Chen et al
|
2009
|
—
|
—
|
Maxillary bone
|
—
|
Excision
|
—
|
None
|
0
|
—
|
—
|
13
|
Kadom et al
|
2009
|
14
|
M
|
Ethmoid sinus
Frontal bone
Fontal sinus
|
Diplopia
Exophthalmos
HA
Nasal obstruction
|
—
|
—
|
None
|
0
|
—
|
—
|
14
|
Castle et al
|
2011
|
43
|
F
|
Ethmoid sinus
|
Sinus pressure
|
—
|
—
|
None
|
0
|
—
|
—
|
15
|
Thomas et al
|
2011
|
49
|
M
|
Nasal cavity
Palate
|
Face pain
Nasal obstruction
Sinus pressure
|
Excision
|
Gross total
|
None
|
0
|
24
|
No
|
16
|
Yoo et al
|
2012
|
New born
|
M
|
Nasal cavity
Nasal bone
|
Nasal obstruction
|
Excision
|
Gross total
|
None
|
0
|
24
|
No
|
17
|
McClurg et al
|
2012
|
49
|
F
|
Nasal bone
Hard palate
|
Nasal obstruction
Maxillary teeth numbness
|
Excision
|
Gross total
|
None
|
0
|
16
|
No
|
Clival/Sellar (7)
|
Case no.
|
Author
|
Year
|
Age
|
Sex
|
Location
|
Clinical symptoms
|
Treatment
|
Gross total/subtotal resection
|
Radiation
|
Radiation dose
|
Follow-up (mo)
|
Recurrence
|
1
|
Linskey et al
|
1990
|
73
|
M
|
Clivus
|
Ataxia
CN 7, 10 impairment
Deafness, Diplopia
Dysphagia
HA
|
Excision
|
Gross total
|
None
|
0
|
3
|
No
|
2
|
Keel et al
|
1997
|
34
|
F
|
Clivus
Nasopharynx
Prepontine Cistern
|
Blindness
Diplopia
HA
|
Curettage
|
Subtotal
|
+
|
68 Gy
|
11
|
No
|
3
|
Keel et al
|
1997
|
65
|
F
|
Clivus
Ethmoid sinus
Sphenoid sinus
|
HA
|
Curettage
|
Gross total
|
None
|
0
|
26
|
No
|
4
|
Keel et al
|
1997
|
42
|
M
|
Clivus
Sphenoid sinus
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
5
|
Patino-Cordoba et al
|
1998
|
41
|
F
|
Clivus
Ethmoid sinus
Nasopharynx
Sella turcica, Sphenoid sinus
|
Ataxia, Deafness, HA
|
Excision x3
|
(1) Subtotal (2) Gross total (3) Gross total
|
(1) + (2) - (3) -
|
—
|
(1) 72 (2) 12 (3) 48
|
Yes x2
|
6
|
Bloom et al
|
2004
|
38
|
F
|
Clivus
Jugular foramen
Occipital bone
|
CN 12 impairment
Dysarthria
Dysphagia
HA
Neck pain
|
Excision
|
Gross total
|
None
|
0
|
5
|
No
|
7
|
Xu et al
|
2011
|
55
|
M
|
Sella turcica
|
Blindness
Decreased ACTH
HA
|
Excision
|
Gross total
|
None
|
0
|
6
|
No
|
Sphenoid/Parasellar (12)
|
Case no.
|
Author
|
Year
|
Age
|
Sex
|
Location
|
Clinical symptoms
|
Treatment
|
Gross total/subtotal resection
|
Radiation
|
Radiation dose
|
Follow-up (mo)
|
Recurrence
|
1
|
Nazeer et al
|
1996
|
66
|
F
|
Nasopharynx
Sella turcica
Sphenoid sinus
|
Nasal obstruction
|
Curettage
|
Subtotal
|
None
|
0
|
12
|
Yes
|
2
|
Keel et al
|
1997
|
51
|
F
|
Ethmoid sinus
Sphenoid sinus
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
3
|
Keel et al
|
1997
|
66
|
F
|
Ethmoid sinus
Nasopharynx
Sphenoid sinus
|
Nasal obstruction
|
(1) Curettage (2) Excision
|
Subtotal
|
(1) − (2) +
|
61 Gy
|
(1) 6 (2) 20
|
Yes
|
4
|
Wu et al
|
1998
|
—
|
—
|
Sphenoid bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
5
|
Wu et al
|
1998
|
—
|
—
|
Sphenoid bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
6
|
Wu et al
|
1998
|
—
|
—
|
Sphenoid bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
7
|
Feuvret et al
|
2005
|
19
|
M
|
Petrous temporal bone
Sphenoid bone
|
Diplopia
|
Excision
|
Subtotal
|
+
|
59 CGE, 45 Gy
|
(1) 14 (2) 12
|
Yes
|
8
|
Feuvret et al
|
2005
|
28
|
F
|
Sphenoid bone
|
CN 6 impairment
Deafness
Diplopia
|
Excision x2
|
Subtotal
|
+
|
59 CGE, 45 Gy
|
48
|
Yes
|
9
|
Vernon and Casiano
|
2006
|
44
|
M
|
Sphenoid sinus
|
Retro-orbital pain
|
Curettage
|
Gross total
|
None
|
0
|
—
|
No
|
10
|
Morris et al
|
2009
|
52
|
F
|
Sphenoid sinus
|
Vertigo
|
Curettage
|
—
|
None
|
0
|
24
|
No
|
11
|
Yu et al
|
2009
|
39
|
M
|
Cavernous sinus
Mandibular ramus
Petrous temporal bone
sphenoid sinus
|
CN 5, 6 impairment
Diplopia
Face numbness
|
Excision
|
Subtotal
|
None
|
0
|
6
|
No
|
12
|
Our study
|
2013
|
38
|
F
|
Clivus
Sphenoid bone
|
Diplopia
Nasal obstruction
Rhinorrhea
|
Excision
|
(1) Subtotal (2) Gross total
|
None
|
0
|
12
|
(1) Yes (2) No
|
Orbit/Zygoma (8)
|
Case no.
|
Author
|
Year
|
Age
|
Sex
|
Location
|
Clinical symptoms
|
Treatment
|
Gross total/subtotal resection
|
Radiation
|
Radiation dose
|
Follow-up (mo)
|
Recurrence
|
1
|
Carr et al
|
1992
|
41
|
F
|
Orbit
Zygoma
|
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
18
|
No
|
2
|
Wolf et al
|
1997
|
35
|
F
|
Frontal bone
Orbit
Sphenoid bone
|
HA
|
Excision
|
Gross total
|
None
|
0
|
—
|
—
|
3
|
Hashimoto et al
|
1998
|
32
|
M
|
Ethmoid sinus
Frontal sinus
Nasal cavity
Orbit
|
Exophthalmos
Painless swelling
|
Excision
|
—
|
None
|
0
|
24
|
No
|
4
|
Bucci et al
|
2006
|
51
|
M
|
Orbit
Zygoma
|
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
24
|
No
|
5
|
Cruz et al
|
2007
|
10
|
F
|
Ethmoid sinus
Orbit
|
Exophthalmos
|
Excision
|
Gross total
|
None
|
0
|
12
|
No
|
6
|
Heindl et al
|
2009
|
37
|
F
|
Frontal bone
Orbit
|
Exophthalmos
HA
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
24
|
No
|
7
|
Khalatbari et al
|
2012
|
14
|
M
|
Orbit
Sphenoid bone
|
Exophthalmos
Face pain
Swelling
|
Excision
|
Gross total
|
None
|
0
|
96
|
No
|
8
|
Ditta et al
|
2012
|
51
|
F
|
Orbit
Sphenoid bone
Zygoma
|
Exophthalmos
Face pain
HA
|
Both
|
Gross total
|
None
|
0
|
5
|
Yes
|
Temporal bone/Occiput (15)
|
Case no.
|
Author
|
Year
|
Age
|
Sex
|
Location
|
Clinical symptoms
|
Treatment
|
Gross total/subtotal resection
|
Radiation
|
Radiation dose
|
Follow-up (mo)
|
Recurrence
|
1
|
Dumas et al
|
1994
|
43
|
F
|
Jugular foramen
Petrous temporal bone
Occipital bone
|
Painless swelling
Intermittent LOC
tongue atrophy
|
—
|
—
|
None
|
0
|
—
|
—
|
2
|
Maruyama et al
|
1994
|
67
|
M
|
Jugular foramen
Petrous temporal bone
|
CN 5–10 impairment
Deafness
HA
Nausea
|
Excision
|
Subtotal
|
None
|
0
|
—
|
—
|
3
|
LeMay et al
|
1997
|
22
|
M
|
Mastoid temporal bone
|
Deafness
HA
Otalgia
|
Excision
|
Gross total
|
None
|
0
|
3
|
No
|
4
|
Patino-Cordoba et al
|
1998
|
20
|
M
|
Mastoid temporal bone
|
Deafness
|
Excision
|
Gross total
|
None
|
0
|
—
|
—
|
5
|
Wu et al
|
1998
|
—
|
—
|
Occipital bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
6
|
Wu et al
|
1998
|
—
|
—
|
Occipital bone
|
—
|
—
|
—
|
None
|
0
|
—
|
—
|
7
|
Suzuki et al
|
1999
|
49
|
M
|
Squamous temporal bone
|
Blindness
Painless swelling
|
Excision
|
Gross total
|
None
|
0
|
—
|
—
|
8
|
Tarhan et al
|
2000
|
44
|
F
|
Tympanic temporal bone
|
Facial pain
|
Excision
|
Gross total
|
None
|
0
|
—
|
—
|
9
|
Otto et al
|
2007
|
58
|
F
|
Mastoid temporal bone
|
Syncope
Vertigo
|
Excision
|
Gross total
|
None
|
0
|
6
|
No
|
10
|
Thompson et al
|
2009
|
33
|
F
|
Mastoid temporal bone
Stylomastoid foramen
|
CN 7 impairment
|
Excision
|
—
|
None
|
0
|
—
|
—
|
11
|
Crocker et al
|
2009
|
22
|
M
|
C1
Clivus
Occipital bone
|
Deafness
|
Excision
|
Gross total
|
None
|
0
|
24
|
No
|
12
|
Ozek et al
|
2011
|
17
|
M
|
Cerebropontine angle
Petrous temporal bone
|
CN 6, 7 impairment
Deafness, Diplopia
HA
|
Excision
|
Subtotal
|
None
|
0
|
—
|
No
|
13
|
Wang et al
|
2011
|
31
|
M
|
Petrous temporal bone
|
HA
|
Excision
|
—
|
None
|
0
|
—
|
—
|
14
|
Gupta et al
|
2012
|
42
|
M
|
Mastoid temporal bone
Sigmoid sinus
|
Deafness
Otalgia
|
Biopsy
|
—
|
None
|
0
|
—
|
—
|
15
|
Sharma et al
|
2012
|
12
|
F
|
Squamous temporal bone
Zygoma
|
HA
Otalgia
Painful swelling
|
Excision
|
Gross total
|
None
|
0
|
—
|
No
|
Abbreviations: ACTH, adrenocorticotropic hormone; CGE, cobalt gray equivalents; CMF,
chondromyxoid fibroma; CN, cranial nerve; F, female; Gy, gray; HA, headache; LOC,
loss of consciousness; M, male; Mo, months.
Reported cases of CMF in the calvarium and skull base. A literature review was performed
identifying all cases of CMF. Eight calvarial tumor cases were reported. Skull base
tumors were further categorized into sinonasal (17 cases), clival/sellar (7 cases),
sphenoid/parasellar (12 cases), orbit/zygoma (8 cases), and temporal bone/occiput
(15). Relevant data were extracted including, presenting clinical symptoms, treatment,
gross total versus subtotal resection, radiation therapy if used, follow-up time,
and recurrence.
Discussion
CMF is an exceptionally rare tumor, primarily affecting the long bones and accounting
for less than 1% of all osseous neoplasms.[1] Its occurrence in the craniofacial skeleton is even less frequent. Wu et al, in
their review of 278 cases, reported only 15 tumors involving the skull and facial
bones.[4] The location, demographics, presenting symptoms, and treatment of all of calvarial
and skull base CMF cases published since 1990 are summarized in [Table 1].
In our literature review, we have found 67 published cases of cranial CMF since 1990.
The mean age of all calvarial and skull base CMFs is 38.2 years, which is consistent
with the literature.[4] Patients with clival/sellar and sphenoid/parasellar sites of origin were, on average,
a decade older than those with other sites of origin. Ages ranged from newborn to
73 years. Additionally, we found a slightly greater predilection for CMF in females,
with 35 females and 24 males. This is conflicting in the literature with some studies
reporting a slight male predilection and others a 2:1 female-to-male occurrence. We
found a slight male predominance in the temporal bone/occipital site subgroup. Of
the cases affecting the cranium, the sinonasal structures were affected most commonly,
with the second most common tumor location being the temporal bone and occiput. Most
tumors rarely affected a single bone, and therefore appeared to grow without respect
to the bony anatomy by involving multiple surrounding bones. Most patients were symptomatic
at the time of presentation. The insidious onset of symptoms can result in a potentially
delayed diagnosis for skull base lesions.[12] Symptoms included painless or tender swelling, headache, nasal obstruction, exophthalmos,
diplopia, deafness, and otalgia. The most common presenting symptom for calvarial
CMF was swelling. For the skull base lesions, the most common presenting symptoms
appeared to be related to their respective locations. For sinonasal CMF, the most
common presentation was nasal obstruction, whereas clival/sellar lesions presented
most commonly with headache. Sphenoid/Parasellar lesions presented with diplopia and
orbital/zygomatic CMF presented most commonly with exophthalmos. Last, temporal bone/occipital
CMF was most commonly associated with deafness at presentation.
Given this tumor's rare propensity for the calvarium and skull base, we also reviewed
our own institution's experience with CMF. Since 1957 to present, MDACC has seen 36
patients with CMF. Of these patients, there were two cases affecting the spine: one
at C2 and the other at S1/ilium. There were only one calvarial case and one skull
base case,[13] both reported here.
Radiologic findings are not diagnostic, but they can offer insight into the diagnosis
before intervention. Classically CMF is described as a “radiolucent, lobulated, circumscribed
lesion with a sclerotic rim and cortical expansion or erosion”[14] and calcification is rare. Because of the low occurrence rate of this tumor, MRI
findings have not been clearly established. However, similar to other bone tumors,
CMF has low signal on T1-weighted and high signal on T2-weighted images owing to its
cartilaginous nature.[14] The most challenging aspect to radiologic diagnosis of CMF is the high variability
of involved sites. Therefore suspicion for CMF should be maintained when evaluating
solitary bone lesions.
Histopathologic analysis of CMF reveals a myxoid lesion containing a paucicellular
center, bland stroma cells, reactive boney spicules, and hyaline cartilage with up
to 75% of lesions in the skull and facial bones also containing matrix calcifications.[8]
[15] Though not always present, the characteristic features of CMF include lobular appearance,
chondromyxoid stroma, and fibrous tissue with multinucleated giant cells.[16] Nielsen et al performed ultrastructural examination on six tumor samples finding
populations of cells with features of three different cell types: chondrocytes, myofibroblasts,
and a mixture of both chondrocytes and myofibroblasts.[17] It should be noted that if the lesion shows significant atypia or mitotic activity,
the diagnosis of CMF should be reconsidered. CMF is most commonly found to be positive
for vimentin, smooth muscle actin, desmin, S-100 (variably), and CD34.[18] Generally CMF is negative for pancytokeratin, carcinoembryonic antigen (CEA), and
GFAP, and also has a low proliferation rate visualized by Ki-67 staining.[19] Veras et al describe SOX9 staining in a case of sinonasal CMF. SOX9 has been previously
described as a chondrogenesis “master regulator” and plays a role in early-phase chondrocyte
differentiation.[15]
Chondrosarcoma, chondroblastic osteosarcoma, fibrous dysplasia, chondroblastoma, and
chordoma are included in the differential diagnosis.[20]
[21] This is an important distinction to make given the relatively benign nature of CMF.
Low-grade chondrosarcomas and CMF share stellate cells, S-100 protein stain positivity,
and negative keratin stain. However, chondrosarcomas are more infiltrative than CMFs,
which tend to “push” adjacent bony trabeculae.[10] Additionally, chondrosarcomas lack the fibrous component seen in CMF.[22] Desai et al, in their study of 10 CMF cases, reviewed the characteristics of the
histologic differential diagnosis.[20] Chondroblastic osteosarcoma diagnostically has osteoid production, of which CMF
does not, but it may be difficult to differentiate when there are large patches of
CMF-like tissue present. Fibrous dysplasia has a myxoid appearance, but it is differentiated
from CMF by its irregular osteoid seams. Chondroblastoma has prominent calcifications
and an eosinophilic polygonal cytoplasm that is differentiated from the stellate cytoplasm
of CMF. Last, chordoma tends to have large tumor cells, epithelioid with eosinophilic
or vacuolated cytoplasm arranged in nests or cords.[22] Additionally, chordoma stains positive for S-100, epithelial membrane antigen (EMA),
and cytokeratins whereas CMF is only positive for S-100.[22]
Though it had previously been thought that CMF is an acquired lesion, there is evidence
suggesting a possible genetic link. Though cytogenetic studies are limited, Smith
et al report there are 14 cases of CMF in the literature with known karyotypes. Notably
11 of the 14 cases had nonrandom clonal abnormalities of chromosome 6. In particular,
rearrangements of the chromosome 6 long arm were most frequent, with four of the cases
having pericentric inversion inv(6)(p25q13).[23] Importantly, chromosome 6 has been implicated in normal cartilaginous development,
carrying genes BMP6 (bone morphogenetic protein 6), COL9A1 (collagen type 9 α 1),
COL10A1 (collagen type 10 α 1), and IGF2 (insulin-like growth factor 2). Additionally,
supporting the possible genetic propensity for CMF, our literature review revealed
three cases of congenital CMF presenting in newborns.
Recommended first-line treatment is surgical resection.[6] Given the benign nature of CMF, surgery can provide a cure. In our literature review,
most patients received excision. Of the 67 cases reported here, 43 had excision, 6
curettage, and 2 received both. Two patients received only biopsy, and 14 cases did
not report treatment. Of all the cases included here, there were nine recurrences.
All but one case of recurrence was associated with subtotal resection, five with excision
and three with curettage. Only one recurrence occurred in the setting of gross total
resection in which the patient had the extraosseous component excised, while the bone
itself was curetted until all visible tumor removed. Twenty-five cases had no data
on recurrence.
Efficacy and need for radiotherapy is controversial. Some authors have argued in support
of postoperative radiation to prevent local recurrence,[24] whereas others have reported concern for secondary risks of irradiation induced
malignant transformation.[25] It remains to be clear if radiotherapy is of benefit in patients with subtotal resection
or curettage. In our literature review, five patients received radiotherapy. Dosing
ranged from 50 to 68 Gy. In two cases, the patient also received proton therapy, 59
CGE with 45 Gy. No dosing recommendations are available for CMF, but Feuvret el al
proposed 55 to 60 Gy, consistent with other benign tumors.[26] Feuvret et al believe that radiotherapy should be part of standard treatment and
proposed a treatment flow diagram for skull CMFs. Recommendations for radiation include
patients who are unresectable or received curettage or partial resection in vital
neurologic areas, or have a recurrent tumor.[26] In our literature review, four of the five patients who received radiation had recurrence
postradiation. All of the patients who received radiotherapy had an initial subtotal
resection. Though efficacy of radiotherapy in the setting of subtotal cranial CMF
resection cannot be dismissed, our review did not show a benefit.
One of our patients and three patients identified in our literature review had symptom
onset and subsequent diagnosis during pregnancy. This raises the possibility that
these tumors are hormonally sensitive. To our knowledge, however, there is only one
reported case where a hormonal influence was potentially associated with CMF.[27] Cytogenetic analysis of a scapular CMF revealed mutation in the parathyroid hormone/parathyroid
hormone-related peptide receptor gene (PTH/PTHrP). Halbert et al indicate that this
suggests the existence of autocrine/paracrine regulatory loops thought to be essential
for normal chondrocyte maturation and/or endochondral bone formation.
Conclusion
Cranial CMF is rare, and consequently frequently misdiagnosed. Key features of diagnosis
are radiographic and histologic findings. It is important to keep CMF in the differential
diagnosis when evaluating solitary cranial bone lesions, as CMF is curable by total
excision. Total resection is the best treatment, and should be the goal of any surgical
intervention. Curettage results in high recurrence rates. Radiotherapy in the setting
of subtotal resection or recurrence cannot be definitively recommended and needs further
investigation.