Keywords
giant cell reparative granuloma - reactive pseudoneoplasms - giant cell - reparative
granuloma
Introduction
Giant cell granuloma (GCG) is a rare, benign, non-neoplastic lesion of the head and
neck, most commonly occurring in the mandible or maxilla.[1]
[2] Few cases of central GCG arise within the skull base.[3] There are several cases of GCG arising in the temporal bone.[4]
[5]
[6]
[7]
[8]
[9]
[10]
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[14] Initially referred to as a “giant cell reparative granuloma,” it is now more commonly
referred to as “giant cell granuloma,” This is due to the fact that the once perceived
notion that the lesion represented an attempt to repair areas of injury. However,
it has been shown to occur without a history of trauma. Also, some cases have a more
destructive nature.[3]
[7] Our case represents a rare finding of GCG occurring within the right temporal bone
including attachments to the dura. This lesion was associated with CNS symptoms and
was believed to be something more ominous. The prognosis is excellent following resection.
Case Report
A 27-year-old African American male presented with a history of headaches, fatigue,
lightheadedness, and difficulty concentrating. His symptoms had progressed slowly
over the course of 4 to 5 years. The patient had no pertinent medical history, but
his social history included being a mixed martial arts fighter. Physical examination
was unremarkable. A computed tomography (CT) scan of the head revealed a lytic lesion
in the right temporal bone above the temporomandibular joint with internal calcifications
([Fig. 1]). A right temporal craniectomy with resection of the calvarial lesion was performed
([Fig. 2]). Upon removal, the lesion was found to have attachments to the dura and extensions
into the middle cranial fossa were present.
Figure 1 Preoperative computed tomography scans demonstrating a lytic lesion.
Figure 2 Postoperative computed tomography demonstrating the location of surgical resection.
Methods
Hematoxylin and eosin (H&E)-stained sections showed a dense spindle cell lesion with
frequent giant cells and areas with numerous mononuclear cells. There were also areas
of fibrosis, reactive bone formation, and extravasated red blood cells ([Fig. 3]). The lesion appeared very similar to a giant cell tumor of tendon sheath; however,
the location within the temporal bone excluded that diagnosis. The differential diagnosis
included meningioma, giant cell tumor, brown tumor, histiocytosis, and other spindle
cell neoplasms. An immunohistochemical (IHC) evaluation was performed using CD68 (clone
KP-1, Ventana, Tuscan, AZ, USA), and CD163 (Biocare Medical, Concord, CA, USA), S100
(Ventana, Tuscan, AZ, USA), synaptophysin (Cell Marque, Rocklin, CA, USA), and EMA
(Cell Marque, Rocklin, CA, USA), as well as an iron stain.
Figure 3 Low-power (A) and high-power (B) views showing the mesenchymal proliferation, giant
cells, hemorrhage, and hemosiderin.
Results
IHC showed the lesional cells to be positive for CD68 and CD163, confirming histiocytic
origin ([Fig. 4]). IHC stains were negative for S100, synaptophysin, and EMA. The iron stain was
strongly and diffusely positive, highlighting the hemorrhage ([Fig. 5]). These H&E and IHC findings were consistent with a giant cell granuloma of the
temporal bone.
Figure 4 Lesional cells are positive for CD68.
Figure 5 An iron stain highlights the copious amount of hemosiderin present.
Discussion
The first case of GCG in the temporal bone was reported in 1974 by Hirschl and Katz.[14] Since then, there have been additional cases reported in the literature.[4]
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[14] GCG has a female predilection and is commonly seen early in the second decade of
life.[10] The etiology is unknown; however, it is theorized that trauma and inflammation may
be a risk factor, as represented in this case. The suggested pathological process
of posttraumatic granuloma formation begins with hemorrhaging into the bone and excessive
macrophage (giant cell precursor) migration into the injured tissue.[15] It has also been found that chronic inflammation giving rise to tissue proliferation
may also increase the incidence of granuloma formation.[3]
[12]
[13]
[14]
[15] Radiographic findings tend to demonstrate an expansile radiolucency.[2] Microscopic examination reveals extravasated erythrocytes, an extensive amount of
hemosiderin, and clusters of multinucleated giant cells within a scaffold of cellular
spindle cells.[2] Positive histological staining includes iron, CD68, and CD163.
The differential diagnosis should consist of giant cell tumor, brown tumor, and aneurysmal
bone cysts.[2] GCG is currently considered a benign non-neoplastic lesion. To date, there are no
malignant transformations nor metastases reported.[10] It is believed that GCG is often misdiagnosed as other lesions such as giant cell
tumor and brown tumor. It is crucial to differentiate these lesions due to the malignant
nature of giant cell tumors.
The treatment currently is surgical resection. Numerous GCG cases that were treated
surgically have reported no features of recurrence on postoperative follow-up ranging
from 7 months to 15 years.[3]
[5]
[8]
[12]
[13] Supplementary treatments have included corticosteroid intralesional injection and
calcitonin for aggressive features such as bony invasion by GCG.[3]
[12]
Conclusion
GCG is a rare, benign, non-neoplastic lesion of the head and neck. Originally believed
to be related to injury or trauma, we now know that these cases can arise de novo
and can have a destructive nature. Our case of GCG occurring within the right temporal
bone including attachment to the dura and mental status changes shows where these
lesions can be aggressive. In addition, the patient's history of mixed martial arts
fighting supports the increased risk associated with trauma. As it is hypothesized
that GCG is often misdiagnosed, it is crucial to differentiate these lesions from
others with a malignant potential. Appropriate diagnosis is supported by patient presentation,
history, imaging, pathological findings, and response to surgical resection. Surgical
resection remains the treatment of choice along with supplementary corticosteroid
injection, and calcitonin if the lesion is considered aggressive. With correct treatment
the prognosis is excellent.
