Keywords
Meckel cave - metastasis - breast metastasis - schwannoma - meningioma - trigeminal
tumors
Palavras-chave
cavo de Meckel - metástase - metástase de mama - schwannoma - meningioma - tumor trigeminal
Introduction
The Meckel cave is a small dural pouch, filled with liquor, which is located at the
petrous apex of the temporal bone and contains the sensitive ganglion of the trigeminal
nerve. Tumors in this region are quite rare, and they are usually benign. The most
common tumors are fifth-nerve schwannoma and meningioma.[1]
[2] We report the case of a patient who had breast metastasis in the Meckel cave presenting
as a schwannoma of the fifth nerve.
Case Report
A 67-year-old female patient came to our service complaining of facial hypoesthesia
and diplopia. The patient reported she had started with hypoesthesia on the right
face ∼ 1 year before. Initially, there was only a slight numbness, but it progressed
to a complete loss of sensation. In addition, the patient reported that in the previous
three months she had started to show diplopia mainly when looking to the right side.
The patient had no previous comorbidities. Upon the neurological examination, the
patient presented tactile and thermoalgesic hypoesthesia in the entire right hemiface,
slight atrophy of the masseter muscle, as well as paresis of the VI cranial nerve,
identified by a slight convergent strabismus. The direct and consensual corneopalpebral
reflex was abolished on the right side. The patient denied any type of facial pain.
The rest of the exam was normal.
Apparently, the patient was previously healthy. However, she had treated a breast
cancer with chemotherapy in 2017, and had achieved complete remission of the disease.
Initially, a magnetic resonance imaging scan of the skull was requested. This exam
showed an expansive lesion in the projection of the right trigeminal cistern, measuring
around 2.7 × 1.2 cm, with extension to the tentacle, cavernous sinus and inferiorly
to the Gasser ganglion, with homogeneous contrast enhancement ([Fig. 1]).
Fig. 1 T1-weighted magnetic resonance image; (A) axial, (B) sagittal, and (C) coronal views showing an expansive lesion in the trigeminal cistern on the right,
extending to the tentorium, cavernous sinus, and inferiorly to the Gasser ganglion,
with contrast enhancement.
Due to the prolonged and insidious clinical scenario and the rarity of metastases
in the Meckel cave, our main diagnostic hypothesis was fifth-nerve schwannoma, especially
due to its higher prevalence and its clinical manifestations. However, the patient
also had another extra-axial lesion, measuring 1 cm, located in the left frontal parasagital
region, which captured contrast homogeneously, raising the hypothesis of multiple
meningiomas, although there was no dural tail. In addition, the metastasis hypothesis
had not been ruled out; however, it was unlikely, since the primary cancer had been
controlled for a long time, and the progression of current symptoms occurred quite
insidiously. Perineural spread of carcinomas from the infratemporal or pterygopalatine
fossae can also invade the cavernous sinus; nonetheless, we consider this type of
tumor to be unlikely, since they are extremely rare, and fat obliteration has not
been observed in these fossae.
Surgical treatment of the lesion was indicated, with an interdural approach to the
Meckel cave. Intraoperatively, we were able to easily resect the entire lesion. In
the postoperative period, the patient progressed well and was quickly discharged in
good general condition.
In the one-month postoperative follow-up, the patient presented a significant improvement
in hypoesthesia in the face, as well as an improvement in strabismus. However, she
still persisted with diplopia when looking to the right. On the anatomopathological
analysis of the lesion, a breast-cancer metastasiswas identified. Subsequently, the
patient was referred to the oncologist, who performed an extensive investigation to
search for other metastatic sites, and indicated a complementary treatment with radiotherapy.
No other metastic sites were found.
Discussion
Neoplasms of the Meckel cave are extremely rare, and correspond to ∼ 0.5% of all intracranial
neoplasms.[1] Most lesions in this region are benign, with fifth-nerve schwannoma being the most
common lesion by far. In addition, several other benign lesions, such as epidermoid
cysts, lipomas, chondromas, among others, have also been described.[1]
[3] However, malignant neoplasms are not common.
Lesions to the Meckel cave may expand and injure the fifth-nerve ganglion or invade
the posterior fossa and injure the fifth nerve in its cisternal portion. When the
lesion affects the ganglion, the patients generally have facial pain; however, when
there is nerve involvement alone, the complaint of facial pain is not usually important,
and hypoesthesia is the most common symptom.[4] Further complaints of diplopia, paresis and atrophy of the chewing muscles and exophthalmos
are also common, especially in benign tumors when there is an anterior extension of
the tumor. There may still be facial paralysis, hearing loss, and absence of the corneal-eyelid
reflex.
In the case herein reported, the patient had both a lesion in the cavity itself and
in a cisternal portion, which ended up manifesting without a painful condition.
Soni et al[5] evaluated 21 cases of metastasis of the Meckel cave and compared them with the case
series in the literature on schwannomas and meningiomas, and identified that patients
with malignant tumors of the Meckel cave are more likely to develop pain, paraesthesia
and motor deficit when compared with patients with schwannomas and cavity meningiomas.
In addition, the average time until the development of metastasis is also an important
differentiating factor. Soni et al.[5] identified an average of 15 months for the development of metastasis in the Meckel
cave, while Delfini et al.[6] identified 33 months for meningiomas, and McCormick et al.,[7] 39 for fifth-nerve schwannomas. Our patient presented metastasis at ∼ 12 months,
which was already a sign more compatible with metastasis of the Meckel cave. If it
were a metastasis in almost any other location of the central nervous system, 12 months
of presentation would speak more in favor of a benign neoplasm; however, in the Meckel
cave, a duration with this average seems to be more characteristic of malignant neoplasms.
Conclusion
Our case illustrates a case of an elderly patient with a previous history of breast
cancer already in remission, who had a single brain metastasis in the Meckel cave
presenting as a schwannoma.
In the vast majority of cases, the first hypotheses of neoplasms in the Meckel cave
are schwannoma and meningioma, especially if the patient has no history of previous
neoplasia. However, although Meckel cave metastases are less likely, they should be
considered, and further investigation of a primary site should be performed, especially
in the case of older patients with a history of previous neoplasia and faster clinical
presentation.
