1
INTRODUCTION
Infantile myofibroma is a rare benign tumor of myofibroblasts, primarily
affecting infants under the age of two, with a notable prevalence in
newborns (54%)1. These tumors typically
manifest in the head and neck region, presenting a wide clinical
spectrum ranging from spontaneous regression to severe complications,
including multi-organ involvement and mortality. Due to its diverse
clinical presentation, infantile myofibroma is often misdiagnosed. The
tumors are most frequently located in the scalp, forehead, parotid
region, and oral cavity.
Infantile myofibromas are classified into solitary and multicentric
forms, with solitary lesions accounting for approximately 74% of cases.
Solitary myofibromas predominantly occur in the skin, muscle,
subcutaneous tissue, and bone, gastrointestinal and laryngeal
involvement is rare while orbital involvement is uncommon. The
histological characteristics of orbital myofibroma typically include
tumor cells composed of spindle-shaped fibroblasts and myofibroblasts,
which grow in an infiltrative manner2.
This case report discusses a solitary orbital myofibroma found in a
3-year-old child. Initially, the clinical signs, imaging studies, and
frozen section suggested a diagnosis of an orbital nerve sheath tumor.
However, subsequent immunohistochemical analysis revealed that the
correct diagnosis was indeed infantile solitary orbital myofibroma.
2 CASE
HISTORY/EXAMINATION
We present a case of a 3-year-old male patient who presented with
progressive swelling of the left lower eyelid over the past month. The
child reported no redness, pain, diplopia, or ocular motility
disturbances, and there was no significant family or past medical
history.
Ocular examination revealed visual acuity of 0.5 in the right eye and
0.6 in the left eye. There was noticeable swelling in the right facial
area and lower eyelid, with a palpable, firm mass that was mobile and
non-tender. The position of both eyes was normal, and ocular motility
was intact. Anterior segment examination and fundoscopy showed no
abnormalities.
Ultrasound examination (Figure 1) indicated a mass in the anterior wall
of the right maxillary sinus, raising the suspicion of a neurogenic
tumor. A coronal CT scan of the paranasal sinuses (Figure 2) revealed a
mass in the area of the right maxillary sinus anterior wall, with
differential diagnoses including an infraorbital nerve sheath tumor or a
hemangioma. An enhanced orbital MRI (Figure 3) confirmed the presence of
a mass in the same region, suggesting a neurogenic tumor, most likely a
nerve sheath tumor.
3 DIFFERENTIAL DIAGNOSIS,
INVESTIGATIONS, AND
TREATMENT
Based on the clinical findings and imaging results, with no history of
ocular trauma or surgery, the patient was tentatively diagnosed with a
right-sided orbital nerve sheath tumor, and preparations for surgical
intervention were initiated. Pre-operative evaluations were conducted to
exclude any contraindications for surgery.
The patient underwent an extensive excision of the orbital mass via a
transcutaneous approach to the right lower eyelid under general
anesthesia, along with an artificial bone grafting procedure.
Intraoperative frozen section analysis (Figure 4、Figure 5a) identified
the mass as a spindle cell tumor, primarily considering a nerve sheath
tumor, with definitive diagnosis pending routine histological and
immunohistochemical evaluation.
4 OUTCOME AND
FOLLOW-UP
Postoperatively, immunohistochemical analysis revealing positive
staining for smooth muscle actin (SMA) and calponin, confirming the
diagnosis of infantile solitary orbital myofibroma not orbital nerve
sheath tumor(Figure 5b).Fortunately,the child recovered well, and at the
one-month follow-up, he reported no ocular discomfort, with no signs of
systemic or visceral involvement.
5
DISCUSSION
Differentiating infantile solitary orbital myofibroma from orbital nerve
sheath tumor can be particularly challenging, as both tumors share
several clinical, radiological, and histopathological similarities,
making misdiagnosis possible without thorough examination.
In our case, we reported a 3-year-old child who presented with right
lower eyelid swelling for one month. Initial imaging studies, including
ocular ultrasound, orbital CT, and MRI, strongly suggested a diagnosis
of nerve sheath tumor. Subsequent surgical treatment and intraoperative
frozen section pathology also supported this, identifying the lesion as
a spindle cell tumor, most likely a nerve sheath tumor. However, final
confirmation came after immunohistochemical analysis, which showed
positivity for smooth muscle actin (SMA) and calponin, leading to the
accurate diagnosis of infantile orbital myofibroma.
The misdiagnosis in this case initially arose due to the overlapping
clinical features and imaging characteristics between myofibroma and
nerve sheath tumors. Both are spindle cell tumors commonly found in the
orbit, and both can present with painless proptosis. Patients with
either tumor may seek medical attention due to symptoms such as eyelid
swelling, proptosis, or vision disturbances. Orbital masses from either
tumor type can cause ocular motility restrictions and share similar
imaging appearances on ultrasound, CT, and MRI. Both can appear as
well-defined intraorbital masses with clear borders. On imaging, the
masses may be oval, round, or irregular in shape, sometimes showing
heterogeneous internal echo or signal intensity, which may reflect
cystic degeneration or necrosis within the tumor3.
However, there are subtle but important differences. Nerve sheath tumors
are often located along the path of the nerves and can present with
characteristic features such as a ”dumbbell shape” or the presence of a
small “tail” sign on imaging, reflecting the involvement of a nerve
pathway4. In contrast, myofibromas may have
a different distribution in the orbit. On MRI, nerve sheath tumors tend
to have more uniform signal intensities, while myofibromas may show
mixed signals due to their fibrous and myofibroblastic components.
Despite these imaging clues, definitive diagnosis relies heavily on
histopathology and immunohistochemical studies. In this case, the key to
differentiation was the immunohistochemical markers. The positive
staining for SMA and calponin in our patient’s tumor confirmed the
diagnosis of infantile myofibroma, as these markers are characteristic
of myofibroblastic tumors. Nerve sheath tumors, on the other hand,
typically show S-100 protein positivity, which was not observed in this
case.
Regarding treatment, surgical excision remains the primary therapeutic
approach for infantile myofibroma. Given that the tumor may adhere
tightly to surrounding tissues, special care must be taken during
surgery to preserve critical orbital structures. In our case, the
excision was performed successfully, and the patient had an uneventful
recovery with no post-operative complications.
6
CONCLUSION
Infantile solitary orbital myofibroma is a rare benign soft tissue tumor
that typically occurs in the head and neck region of infants. When it
presents in the orbit, it can lead to symptoms such as proptosis and
restricted ocular motility, impacting the patient’s appearance and
vision5. This case highlights the
diagnostic challenges in differentiating infantile solitary orbital
myofibroma from an orbital nerve sheath tumor due to their overlapping
clinical and imaging features. Although initial signs, imaging, and
frozen section pathology suggested a nerve sheath tumor,
immunohistochemistry was essential for the correct diagnosis of
myofibroma. Careful attention to histopathological details and
immunohistochemical markers is crucial for accurate diagnosis and
appropriate management. Surgical excision remains the mainstay of
treatment, with a favorable outcome as demonstrated in this case.
AUTHOR
CONTRIBUTIONS
Ligang Jiang: writing – original draft; writing – review and
editing.Wencan Wu: writing – review and
editing;Conceptualization.Fangzheng Jiang :project
administration;supervision
FUNDING
INFORMATION
This study was supported by funding from Natural Science Foundation of
Zhejiang Province(Zhejiang Provincial Basic Public Welfare
Project,LGF22H120017)
CONSENT
Written informed consent was obtained from the patient to publish this
report in accordance with the journal’s patient consent policy.
CONFLICT OF INTEREST
STATEMENT
There is no conflict of
interest.