Desmoid Fibromatosis Mimicking a Periapical Lesion In a Gardner Syndrome Patient
CASE PRESENTATION
A 34-year-old female presented to the oral surgery clinic with
occasional pain and a history of endodontic therapy to the
mandibular right first molar (#30). Her medical history is
significant for Gardner syndrome and having been treated for
cancerous lesions of the colon, dermoid cysts and desmoid
tumors of both the abdomen and skin. The patient had also
undergone several bowel resections and subsequent multi-
organ transplant involving the stomach, pancreas, duodenum
and small intestine. Recently, the patient experienced drainage
in the right posterior mandible while brushing her teeth. A
panoramic radiograph showed several dental manifestations
of Gardner syndrome, including multiple osteomas and
dental anomalies (Figure 1).
In addition, the right posterior mandible showed well-defined
periapical radiolucencies with irregular borders extending
from the distal root of #30 to the mesial aspect of tooth #29.
The lesion appears to be causing external root resorption and
violating the PDL space. Although several teeth in the lower
right quadrant have large occlusal fillings, teeth #28 and
#29 were vital, and an intraoral exam revealed no perceptible
disturbances to the area, other than dental caries.
The patient’s oral surgeon was concerned about a metastatic
colon lesion, given the patient’s medical history, and
performed a biopsy in the area to submit for histopathologic
analysis. Intra-operative notes mentioned that the lesion was
“very firm and fibrous” and “did not represent the normal
inflammatory periapical lesion that one typically sees.”
Gross examination of the specimen revealed one piece of
tan-brown connective tissue with the consistency of a solid
tumor. The histopathology (Figure 2) showed a hypocellular
infiltrate of bland-appearing spindled cells in a densely-
collagenous stroma. Background inflammatory cells were not
seen. Upon staining with beta-catenin immunohistochemis-
try, the lesion demonstrated nuclear positivity. This feature
along with the histologic presentation strongly suggested
that the lesion is consistent with a desmoid-type fibromatosis
of the mandible. Furthermore, the histologic characteristics of
the present specimen were similar to the patient’s previously
excised desmoid tumors.
DISCUSSION
Several other pathologic entities bear histopathological
resemblance to desmoid fibromatoses, including collagenous
scar tissue, myofibroma, and Gardner fibroma, the last of which
is considered a precursor lesion to desmoid fibromatosis. 3
Histologically, the organized nature of the fascicles and the
pattern of vascular structures in a non-existent inflammatory
background steered us away from myofibroma and Gardner
fibroma. A diagnosis of desmoplastic fibroma, the intraosseous
counterpart to desmoid fibromatosis, was also considered,
given its histological resemblance to desmoid-type fibroma-
tosis. However, given the nuclear beta-catenin positivity and
the patient’s history of desmoid tumors, we favored a
diagnosis of Gardner syndrome-associated desmoid tumor.
A defining feature of desmoid fibromatosis is positive nuclear
beta-catenin, while the other lesions are almost always
negative for nuclear beta-catenin, even though cytoplastic
expression is variable. 4,5,6
Figure 1. (A) Periapical radiolucency with irregular borders in the mandibular right quadrant extending from the distal of #30 to the mesial of #29.
Osteoma= triangles. (B) Cropped and enlarged image of the dental menifestations of Gardner’s syndrome from A.
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JA NUA RY/F E B R UA RY 2019 | P EN N S YLVA N IA D EN TA L J O U R N A L