Keywords
gummatous lesions - labyrinthitis - meningoneuritis - neurosyphilis - otosyphilis
A 50-year-old man presented with gradually progressive hearing diminution in the left
ear of 9 months duration. It was associated with occasional tinnitus. There was no
ear pain, discharge, or fever. It gradually progressed to near total hearing loss.
Two months later he noticed difficulty in closing the left eye. Two days later, he
started having drooling of food and saliva through the left side of angle of mouth.
There was no history of nasal regurgitation, or choking. He had history of pulmonary
tuberculosis 10 years back. Cranial nerve examination revealed a left facial nerve
and left 12th cranial nerve palsy with normal palatal movement. Otoscopy revealed
minimal tympanic membrane bulge and audiogram showed moderate high-frequency mixed
hearing loss.
Magnetic resonance imaging (MRI) showed T2-weighted (T2W) hyperintense lesions in
the left petrous temporal bone and the mastoid region with a T2W intermediate to hypointense
extra-axial lesion at the left cerebellopontine region ([Fig. 1A, B]). Contrast scan showed homogeneously enhancing dural-based soft tissue lesion in
the premedullary cistern and cerebellopontine region extending into the left internal
acoustic meatus and jugular foramen. Enhancing soft tissue foci were also seen in
the left petrous temporal bone, middle ear, and mastoid along with the involvement
of the labyrinth and the cochlear duct ([Fig. 2]). There was edema involving the adjacent left cerebellum without any enhancing parenchymal
lesions.
Fig. 1 (A) T2W axial images show hyperintense lesions in the left petrous temporal bone (short arrow) and the mastoid region with a T2W hypointense extra-axial lesion at the left cerebellopontine
region (long arrow). (B) T1W images show isointense signal intensity corresponding to the lesions at the
petrous mastoid region and the cerebellopontine region. T1W, T1 weighted.
Fig. 2 This figure shows homogeneously enhancing dural-based soft tissue lesion (short arrow) in the premedullary cistern and cerebellopontine region extending to the ipsilateral
internal acoustic meatus. Enhancing lesions (long arrow) in the petromastoid region with enhancement of the vestibulocochlear nerve.
Temporal bone computed tomography (CT) showed conglomerate lytic lesions in the middle
ear and mastoid air cells ([Fig. 3]). In three-dimensional volume rendering technique images, the lesions showed an
unusual worm-shaped appearance of irregular bone destruction predominantly involving
the petrous apex and mastoid region ([Fig. 4]). There was erosion of the incus with suspicious erosion of the head of the malleus.
There was no erosion of the otic capsule. Diffuse sclerosis of the mastoid along with
diploe widening and sclerosis of the adjacent squamous temporal bone was seen.
Fig. 3 This figure shows conglomerate lytic sclerotic lesions (short arrows) in the left petrous temporal bone, middle ear, and mastoid air cells. Diffuse sclerosis
noted with diploe widening seen at the left mastoid and adjacent squamous temporal
bone.
Fig. 4 VRT images showing worm-shaped appearance (short arrow) of irregular bone destruction predominantly involving the petrous apex. VRT, volume
rendering technique.
Positron emission tomography (PET) CT imaging showed focal FDG (fluorodeoxyglucose)-avid
extraosseous lesions ([Fig. 5]) and minimally FDG-avid erosions at the petrous part of the temporal bone. There
was no PET uptake in the brain or any other part of the body. Differential diagnosis that was considered based on imaging includes cholesteatoma,
squamous cell carcinoma, skull-based osteomyelitis and secondaries.
Fig. 5 PET-CT imaging shows high metabolic uptake area (long arrow) corresponding to the enhancing extradural lesion cerebellopontine and premedullary
region with no extension to the adjacent cerebellum. PET-CT, positron emission tomography-computed
tomography.
Patient underwent craniotomy and dural biopsy. Pathological examination showed fragments
of tissues, with moderate to dense inflammation composed predominantly of plasma cells
and lymphocytes. Occasional histiocytes and neutrophils were noted. Exuberant vascular
proliferation was seen with prominent endothelial cells. There was one focus of endarteritis
obliterans evident and no microorganisms were seen. EVG stain highlighted the endarteritis
obliterans ([Fig. 6]). Immunohistochemistry for Kappa and Lambda showed a polyclonal population. The
report suggested possibility of syphilis.
Fig. 6 (A) Pathological examination shows inflammation composed predominantly of plasma cells
and lymphocytes with focus of exuberant vascular proliferation seen with very prominent
endothelial cells. (B) High power of the end arteritis obliterans.
A reactive quantitative rapid plasma reagin (RPR) titer measured 1:128, and a fluorescence
treponemal antibody absorption test was positive. The patient was treated with intravenous
penicillin G, 4 million units every 4 hours for 6 weeks. There was mild improvement
in the hearing and other cranial nerve symptoms. There was a drop in the RPR titer
to 1:36 after 6 weeks of treatment which empirically confirmed the diagnosis of syphilis.
Follow-up review after 2 months showed some improvement in the cranial nerve palsies
but the hearing loss had not improved further. A follow-up MRI showed significant
reduction in size of the extradural soft tissue at the premedullary cistern and cerebellopontine
angle. There was significant reduction in the enhancement in the inner ear. Based
on clinical, serological, and imaging findings of gummatous lesions in the temporal
bone, meningoneuritis, and labyrinthitis, a final diagnosis of otosyphilis was established.
Discussion
Syphilis is a complex systemic illness with clinical manifestations caused by the
spirochete Treponema pallidum. Syphilis can be classified into four stages according to the clinical manifestations
of the disease. These include primary, secondary, latent syphilis, and tertiary syphilis.[1]
Primary stage occurs 3 to 4 weeks after exposure and presents with the painless chancre.
Secondary stage presents usually with rashes that occurs 4 to 8 weeks after that latent
syphilis is the asymptomatic stage. Tertiary stage may present with cardiovascular
and neurological manifestations.
Neurosyphilis is a common clinical manifestation in the tertiary stage that can present
with meningitis and encephalitis. The central nervous system involvement in syphilis
patients is classified into four syndromes: syphilitic meningitis, meningovascular
syphilis, parenchymatous, and gummatous neurosyphilis.[2]
Otosyphilis may present as a destructive bone disease that may be accompanied by systemic
manifestations of syphilis. Involvement of the inner ear is recognized in the late
congenital, late latent, and tertiary stages of syphilis.[3] Otosyphilis can manifest as a gummatous lesion of the internal auditory canal, a
labyrinthitis, or a luetic osteitis. Other typical pathologic findings are osteomyelitis
and periostitis. Histopathologically, otosyphilis is characterized by obliterative
endarteritis, multinucleated giant cell, and round cell infiltration. Symptoms may
be ranging from sudden or insidious reversible hearing loss, tinnitus, and vestibular
symptoms ranging from dizziness to vertigo. Meniere's disease is close differential diagnosis of this condition with similar clinical
and pathological findings.[4]
When spirochetemia occurs in syphilis, the organisms can infect the deeper vascular
areas of the periosteum, with eventual extension into the Haversian canals and medullary
spaces, resulting in periostitis, osteitis, or osteomyelitis. Disease progression
can develop into osteolytic or osteoblastic changes in the bones, often with superficial
bone involvment.[5] The tumor-like gummatous lesion with formation of the granulation tissue is due
to excessive response of the cell-mediated immune system to T. pallidum. Gummas are uncommon and usually develop in the dura and pia mater over the cerebral
convexity or at the base of brain. In otosyphilis imaging, features like osteitis
and osteolysis may be seen in the temporal bone and gummas in the internal auditory
canal.[6] CT features show irregular bone destruction preferentially involving the outer table
of the skull with unusual “worm-eaten” pattern that is considered characteristic of
calvarial syphilitic involvement on conventional radiographic and gross pathologic
assessment.[5] Single or multiple masses attached to the dura mater can invade the brain parenchyma
with development of symptoms similar to that of primary neuroparenchymal tumors. Other conditions that can mimic such imaging findings include malignancies such as
lymphoma, squamous cell carcinoma, cholesteatoma, and infections like chronic otitis
media. Ogungbemi et al reported patients with acquired syphilis who had bilateral hearing
loss with CT showing features of luetic osteitis of temporal bone. In syphilitic meningitis common imaging features may include leptomeningeal enhancement,
cranial nerve involvement (such as 7th and 8th nerve), focal pachymeningitis, and
syphilitic myelitis.[6]
Meningovascular syphilis may present as large vascular infarcts in cortical and subcortical
locations.[6] In our case multiple gummatous lesions were seen in the petrous part of temporal
bone sparing the otic capsule. The linear extra-axial enhancing soft tissue adjacent
to the premedullary and cerebellopontine cisterns could represent the meningeal involvement
(syphilitic meningitis) which correlated with the positive fluorescence treponemal
antibody absorption test of the CSF. The bone destruction was demonstrated better
by the volume-rendered imaging (using 1-mm thin reconstructed images) than in conventional
bone window. Erosions of the otic capsule and moth-eaten demineralization of the temporal
bone have been described in the literature.[7] On MRI, the gummatous lesions are reported to be isointense relative to the gray
matter in T1W images, hyperintense in T2W images, and show enhancement in postcontrast
imaging. In summary, otosyphilis can present as a manifestation in early neurosyphilis with
or without meningitis or meningovascular manifestation. Imaging presentation in otosyphilis
may be variable depending on the manifestations and hence correlation with the serology
becomes mandatory for diagnosis. To the best of our knowledge, MRI in otosyphilis has not been reported previously.
Otosyphilis, though rare, should be considered as the differential diagnosis of a
destructive lesion of the petrous bone with or without adjacent meningeal involvement.
