Desmoplastic Fibroblastoma in Maxillary Alveolar Bone Mimicking An Odontogenic Lesion: A Novel Case Report with Review of Literature
Zohreh JAAFARI-ASHKAVANDI1, Mehdi YASAMIN SHIRAZI2, Sepideh ASSAR1
1Department of Oral and Maxillofacial Pathology, Shiraz Dental School, Shiraz University of Medical Sciences, Shiraz, Iran
2Department of Endodontics, Birjand Dental School, Birjand University of Medical Sciences, Birjand, Iran
Keywords: Desmoplastic fibroblastoma, Collagenous fibroma, Intraosseous, Maxilla, Oral cavity
Desmoplastic fibroblastoma (Collagenous fibroma) is a rare benign soft tissue tumor that disseminates widely and can be intramuscular or
subcutaneously. There are seven reported cases in the oral cavity so far. We reported a novel case of collagenous fibroma that has been found in
the anterior part of maxilla in a 58-year-old woman as an intraosseous radiolucent lesion that has been discovered during routine radiography.
Histopathologically, spindle and stellate-shaped fibroblasts in a collagen-rich stroma as well as binucleated and multinucleated fibroblasts with
prominent nucleoli were seen. Desmoplastic fibroblastoma could be found in jaw bones and excision of the lesion is curative, and no aggressive
growth has been reported.
Desmoplastic fibroblastoma (collagenous fibroma) is a
rare benign soft tissue tumor that disseminates widely and
can be intramuscular or subcutaneously that has been first
described in 1995 (1,2). This tumor usually affects men
with the age range of 40 to 69 years, though it has also been
reported from 16 to 81 years (2). The largest case series with
63 cases was published in 1998 by Miettinen and Fetsch (2).
Involvement of different anatomic sites by this lesion, such
as chest wall, orbital rim and genital areas were reported (3-
5). The intraoral cases are very rare and Mesquita et al. has
reported the first case in 2001. Parotid gland and palate are
the most reported locations for intraoral lesions (2, 6-8).
Desmoplastic fibroblastoma is usually a firm mobile
slow-growing painless mass that is well-circumscribed,
round to oval, or lobulated (9). Microscopically, it shows
a hypocellular soft tissue mass that is mostly composed
of abundant collagen fibers. Tumor cells are spindle
or stellate-shaped with large nuclei that may contain
eosinophilic nucleoli. In dense fibrotic areas, the cells do
not have any mitotic activity or necrosis (2). Binucleated
cells and multinucleated giant cells may also be observed.
Due to the surrounding collagenous stroma, few amounts
of blood vessels were detected in this lesion. Inflammatory
cells are usually absent (1, 2). By immunohistochemical
staining, the cells show strongly positive immunoreactivity for vimentin and a variable immunoreactivity for smooth
muscle actin (10, 11).
Herein we report a novel case of collagenous fibroma in the
anterior part of maxilla and were unexpectedly presented
as an intraosseous periapical lesion.
A 58-year-old woman was referred to the Dental School
of Shiraz University of Medical Sciences because of an
intraosseous radiolucent lesion that has been discovered
during routine dental examination. The lesion was a wellcircumscribed,
rounded radiolucency with a diameter of
20 mm in association with the root of right upper incisors.
The patient did not report any pain or symptom and
there were no swelling, redness or other changes on the
overlying gingiva. Regional lymph nodes were normal on
clinical examination. The patient's medical history was
not remarkable. According to the vital test examination,
adjacent teeth were diagnosed as vital but root canal therapy
of tooth #2 was done by a general dentist because of this
radiolucent lesion, Three months after root canal therapy,
the endodontist referred the patient for excisional biopsy
because of no healing changes in the area (Figure 1
excisional biopsy was done (Figure 2
) and the lesion was
sent to the Oral and Maxillofacial Pathology Department
for histopathological examination. The formalin-fixed
lesion was a piece of round creamy elastic soft tissue measuring 1.3 × 1 × 1 centimeters and was shiny on its cut
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|Figure 1: Periapical radiograph of the patient after root canal
therapy: A well- defined radiolucent lesion mimicking periapical
Hematoxilyn& eosin stained sections showed a benign, wellcircumscribed
mesenchymal tumor consisting of spindle
and stellate-shaped fibroblasts in a collagen rich stroma.
Some fibroblasts were binucleated and multinucleated with
prominent nucleoli. A few blood vessels were detected.
Inflammatory cells, areas of necrosis, calcification, and mitosis were absent (Figure 3A,B). Masson's trichrome
staining revealed abundunt collagen bundles (Figure 4).
Immunohistochemical (IHC) examination was positive for
vimentin (Figure 5A), SMA, CD34 and S-100 were negative
(Figure 5B). According to these findings, a diagnosis of
desmoplastic fibroblastoma was established. The patient
was examined after 1 year and there was no recurrence of
Click Here to Zoom
|Figure 3: A) Well-circumscribed paucicellular mesenchymal
tumor (H&E; x40), B) Binucleated, stellate fibroblasts with
prominent nucleoli (H&E; x400).
Figure 4: Stroma with abundant collagen bundles (Masson's
Click Here to Zoom
|Figure 5: A) Spindle- and stellate-shaped cells positive for
vimentin (IHC; x200), B) Negative for SMA (IHC; x200).
Desmoplastic fibroblastoma or collagenous fibroma is a
benign fibroblastic/myofibroblastic tumor that typically
occurs subcutaneously. No intraosseous lesion has been
reported so far and the rare bony cases that have been
reported demonstrated erosion on the surface of bone.
Excision of the lesion is curative and no aggressive growth
has been reported (12) .
Seven cases have been reported in the oral cavity so far
in the buccal mucosa, palate, parotid and gingiva. Our
case is the first case that appeared to be intraosseous.
After histopathological evaluation, a scar, desmoplastic
fibroma, neurofibroma, chonromyxoid fibroma, lowgrade
fibromyxoid sarcoma, calcifying fibrous- pseudo
tumor and solitary fibrous tumor were considered in the
differential diagnosis. There was no history of previous
surgery or trauma that could cause a scar. Also there
were no chondroid or myxoid area and no mitosis to
prove chondromyxoid fibroma or fibromyxoid sarcoma.
The lesion was hypocellular with no fascicular pattern
so desmoplastic fibroma was ruled out and there was no
calcification in the lesion for it to be a calcifying fibrous
pseudo tumor. Neurofibroma has a myxoid stroma and
spindle cells with wavy nuclei, which were not seen in our
case. Negative S-100 protein and CD34 staining ruled out
neurofibroma and solitary fibrous tumor.
Desmoplastic fibroblastoma is a tumor of soft tissue
but Merriman et al. reported a case in which the tumor
infiltrated and destructed the scapula (13).
This lesion is very rare in the oral cavity, Mesquita et al.
has reported the first oral lesion in a 37-year-old woman.
In their report, the histopathological features were similar
to our case but clinically, in their case, the lesion was a
solitary and firm 5 cm nodule in the palate and was not
intraosseous. Histopathological sections showed stellate
or spindle-shaped cells in a hypovascular fibrous stroma.
Foci of fat were identified at the edges. Mitotic figures and
tumor necrosis were absent. IHC staining was positive
for vimentin, and a few cells were positive for alphasmooth
muscle actin. Extracellular matrix of the tumor
was immunopositive for type I and type III collagen and
Bhagalia et al. reported a 58-year-old female patient with
the chief complaint of a firm, slow-growing, pedunculated
lesion in the lingual gingival region in relation to the left
3rd molar that had appeared in three months without any
pain or teeth mobility. The connective tissue demonstrated
dense collagen bundles with distribution of spindle to
stellate fibroblastic cells. Multinucleated giant cells were
also observed. Blood vessels and inflammatory cells were
few in number. Fat cells were seen in the center of the
section. Masson's trichrome staining revealed areas positive
for collagen and some areas positive for muscle (11).
Immunohistochemical investigation can be for the definitive
diagnosis and rule out other lesions in the differential
diagnosis of desmoplastic fibroblastoma. We performed
Masson's trichrome staining and immunohistochemical staining for vimentin, S-100 protein, SMA, and CD34. We
found that collagen bundles were abundant by Masson's
trichrome; the cells were strongly positive for vimentin and
negative for S-100 protein, SMA and CD34. It is similar to
the previous cases reported by Mesquita et al. (7).
De Sousa et al. in 2011 reported a 56-year-old man with
a well-circumscribed, sessile, pink-colored mass in the left
buccal mucosa. The mass was single, measuring 35 mm in
diameter. Histopathologic features were similar to our case.
Immunopositivity for vimentin and some positive cells
with Factor XIIIa were seen (10).
In 2014, another case of oral cavity involvement has been
reported in an 8-year-old boy with the complaint of a
swelling in the left buccal mucosa in 6 months. In periapical
radiography, there was no evidence of any periapical or
other osteolytic lesions. Van Gieson special staining was
positive for thick bundles of collagen (12).
Shimoyama et al. reported a case of desmoplastic fibroblastoma
in a 49-year-old woman with a painless slowlygrowing
polypoid palatal mass. Her medical history was
significant for rheumatoid arthritis and she had taken
prednisolone for 4 years. There was no evidence of
root resorption or bone destruction in the radiography.
Histopathologic features were similar to other reported
cases. Thick collagenized desmoid-like areas were also
seen focally. IHC was diffusely positive for vimentin and
there were some positive cells for SMA (14). All of the cases
mentioned above were excised with no recurrence during
follow-up. The case discussed in our report is a 58-year-old
woman, although epidemiologic features of the previous
studies point out to male predominance in the fifth to
seventh decades of life (2). However, case reports in the oral
cavity revealed female predominance. Most of the cases
were found in sixth decades of life, and palate was the most
common site of involvement. Buccal mucosa, gingiva and
alveolar ridge have also been reported with less frequency.
The exact cause of this lesion is still unclear but some
studies stated that it might develop due to a chromosomal
rearrangement (11q12) that could also occur in the fibroma
of the tendon sheath (15). Some authors considered this
lesion as a neoplasm, which does not have a preceding
traumatic or inciting factor (1, 16). The treatment of choice
for this lesion is total surgical excision and the prognosis is
excellent with no recurrence (7).
The authors thank the Vice-Chancellery of Shiraz
University of Medical Science for supporting this research.
The authors would like to thank Dr. Sh. Hamedani (DDS, MSc) from the Dental Research Development Centre for
helping with the English and editorial assistance in the
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