Keywords
middle ear mass - paraganglioma - nonpulsatile
Introduction
Whitish pale looking mass in middle ear cleft throws a variety of diagnosis to consider.
The management of such lesion requires prior good clinical examination and appropriate
radiological investigations to assess its location and extent. We have presented a
case of pale looking mass in middle ear cleft with an array of differentials to consider.
Case Report
A 47-year-old male presented to the outpatient clinic with decreased hearing in left
ear for the past 5 years. Hearing loss was insidious in onset and gradually progressive
that he is unable to hear normal conversations with left ear. It was associated with
left-sided dull aching mild ear pain and buzzing tinnitus (nonpulsatile). There was
no associated otorrhea, bleeding, fever, or facial deviation. On examination, the
pars tensa was intact and draped over a whitish nonpulsatile mass in the middle ear
with a shallow posterosuperior retraction pocket. The high-resolution computed tomography
scan of temporal bone was suggestive of soft tissue density in the left middle ear
over the promontory limited to the mesotympanum with no extension into the mastoid
air cells ([Fig. 1]). Pure tone audiometry of the left ear showed a 27/52 dB HL. After counseling and
informed consent, patient was taken up for excision of mass under general anesthesia.
The standard transcanal with post aural approach was done with vascular strip incision.
Intraoperatively there was a soft pale looking mass involving the mesotympanum with
attachment over promontory and hypotympanic air cells reaching anteriorly up to Eustachian
tube opening ([Fig. 2]).
Fig. 1 HRCT temporal bone showing soft tissue density over the promontory. HRCT, high resolution
computed tomography.
Fig. 2 Pale looking mass in the middle ear over the promontory after elevation of tympanomeatal
flap.
The mass had minimal vascularity with insignificant bleeding on dissection and removal.
The long process of incus was partially eroded with intact stapes and malleus. The
lesion was excised in toto and ossiculoplasty was done with refashioned incus. The
patient had uneventful recovery. The histopathological examination revealed a monomorphic
tumor arranged in clusters and trabeculae separated by thin fibrous septae. The individual
tumor cells had round to oval nuclei, few of which were eccentrically placed, powdery
chromatin, and moderate eosinophilic cytoplasm ([Fig. 3]). Areas of hemorrhage were also identified. No mitosis, necrosis, or atypia was
seen. On immunohistochemistry, it was positive for synaptophysin and CD-56 ([Fig. 4]). Overall features were suggestive of tympanic paraganglioma.
Fig. 3 Histological microphotograph with H&E staining. H&E staining, hematoxylin and eosin
staining.
Fig. 4 IHC with synaptophysin showing tumor cells arranged in clusters. IHC, immunohistochemistry.
Discussion
White mass behind an intact tympanic membrane is an intriguing diagnostic dilemma
that could entice an otologist. What could bring only congenital cholesteatoma to
the mind of an occasional ear surgeon could open a wide array of differential diagnosis
to an experienced mind. An overview of the differential diagnoses of this interesting
clinical presentation is attempted herewith. The presenting symptoms of the patients
with middle ear masses are not particularly helpful in establishing the diagnosis.
Owing to the location most of the patients have symptoms of aural fullness, conductive
loss of hearing, tinnitus and rarely dull aching kind of pain. In spite of extensive
differentials, the location and the appearance of the middle ear mass can give an
idea about the histology. The classical presentation of congenital cholesteatoma is
an asymptomatic white mass behind an intact tympanic membrane. The majority of the
lesions were found to be present in the anterosuperior quadrant.[1]
Paraganglioma in this region presents with pulsatile middle ear mass. The term tympanic
paraganglioma is used for masses confined to middle ear cleft with intact jugular
bulb whereas jugular paraganglioma arise from the dome of jugular bulb in the hypotympanum.
Due to the close proximity of tumor to hypotympanum and jugular bulb the exact site
of origin is sometimes difficult to determine.[2]
Glomangioma or “true” glomus tumor is one of the rarest differentials for middle ear
mass behind an intact tympanic membrane. Arising from the smooth muscles of glomus
bodies, the clinical presentation in one of the reported cases included had whitish
mass behind tympanic membrane with pulsatile tinnitus and hearing.[3]
A vestibular schwannoma though rare could also present in a similar way.[4] Some postulate that the tumors are of intralabyrinthine in origin and extend medially
toward the cerebellopontine angle and laterally into the middle ear via the round
window.[5] Other neurogenic tumors like facial nerve schwannoma and Jacobson’s nerve schwannoma
also form middle ear masses, albeit rarely.[6] These masses present similarly to a glomus tumor. Even imaging findings are quite
similar and virtually indistinguishable. Intraoperatively these tumors could be seen
as tan-pink, firm mass with prominent superficial vasculature.
Another uncommon differential to be considered is middle ear adenoma and are same
as the neuroendocrine (carcinoid) tumors.[7] There are also reports of high riding jugular bulb with intact thick bone presenting
as whitish mass in the mesotympanum.[8]
In spite of the typical location of the tumor, tympanic paraganglioma was not on the
top of our list of differentials for the mass, in view of the scanty vascularity.
The lesion was neither showing any pinkish or reddish hue nor pulsations on otoscopy
or examination under microscope. Even though it appears that more the vascular components
in the lesion, more should be the bleeding, no such correlation could be found out
despite extensive search. The specimen of tympanic paraganglioma under consideration
did show more than usual fibrous stroma in comparison to the vascular channels, but
objective estimation of the same is very difficult, if not impossible. This aspect
of vascular tumors of head and neck thus needs further studies and evaluation.
Conclusion
A long list of differential diagnosis should be kept in mind while dealing with white
pale looking mass behind an intact tympanic membrane. Intraoperative finding of less
than expected bleed should not be a criterion for ruling out paraganglioma and a histopathological
examination should always be obtained before making a final diagnosis.
