Otology & Neurotology 37:e180–e181 ß 2014, Otology & Neurotology, Inc.
Imaging Case of the Month
Intradiploic Epidermoid of Temporal Bone Presenting as Pulsatile Tinnitus Jung Min Lee, Jae Ki Kim, Seong Kyeong Yang, and Joong Keun Kwon Department of Otolaryngology–Head and Neck Surgery, Ulsan University Hospital, Ulsan University College of Medicine, Ulsan, Republic of Korea
Pulsatile tinnitus is characterized by a rhythmic sound that is synchronous with the patient’s heartbeat. Causes of pulsatile tinnitus are various and well documented in the literature. Venous causes of pulsatile tinnitus include a dehiscent jugular bulb, high flow through condylar or mastoid vein, local venous stenosis, idiopathic intracranial hypertension, sigmoid sinus diverticulum or dehiscence, and superior canal dehiscence associated with the superior petrosal sinus. In this case, intradiploic epidermoid caused pulsatile tinnitus by eroding the bony walls of the sigmoid sinus and posterior fossa.
and demonstrated a high signal intensity on T2-weighted imaging (Fig. 1C). Diffusion-weighted MRI showed hyperintensity in the corresponding area consistent with restricted diffusion (Fig. 1D). Transmastoid removal of the mass was performed under general anesthesia on full patient consent. A cystic mass with densely accumulated keratin flakes was observed, which had eroded the bony walls of the sigmoid sinus and posterior fossa, compressing both structures (Fig. 2). The mass reached 2.7 cm in maximal length, and the entire cyst was carefully removed. The exposed sinus and dura were covered with harvested cortical bone dust and tissue glue.
CASE A 50-year-old nonobese woman (body mass index, 22.5) presented with constant left-sided pulsatile tinnitus for 3 months, with no other medical history. She found the symptom increasingly distressing. A full head and neck examination was performed. Otoscopy did not reveal any mass behind clear tympanic membrane, but a pulsatile movement of the posterosuperior quadrant was observed. The tinnitus could not be detected on auscultation over the mastoid, eyes, forehead, or neck. Subjectively, the tinnitus decreased when the patient turned her head to both sides but was not diminished on compression of the ipsilateral jugular vein. Pure-tone audiometry was normal with mild ipsilateral air-bone conduction gap (bone conduction hearing, 9 dB; air conduction hearing, 14 dB). The patient underwent computed tomography (CT) and magnetic resonance imaging (MRI). CT scan revealed a 2-cm mass lesion in the diploic space of the left temporal bone posterior to mastoid air cells. The mass had eroded the mastoid cortex and bony wall over the posterior fossa and sigmoid sinus, compressing the sinus (Fig. 1A). On MRI, the lesion was slightly hyperintense on nonfat saturation T1 (Fig. 1B)
FIG. 1. CT and MRI scans of temporal bone. A, Axial view of CT scan shows left-sided mastoid mass eroding both the mastoid cortex and sigmoid sinus bony wall. B, Axial nonenhanced T1-weighted MR image exhibits some hyperintensity of the mass. C, Corresponding axial T2-weighted image. D, Diffusionweighted image shows focally restricted diffusion in the mass (arrow).
Address correspondence and reprint requests to Joong Keun Kwon, M.D., Department of Otolaryngology–Head and Neck Surgery, Ulsan University Hospital, 290-3 Jeonha-dong, Dong-gu, Ulsan, Republic of Korea; E-mail: [email protected] The authors disclose no conflicts of interest.
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Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
INTRADIPLOIC EPIDERMOID OF TEMPORAL BONE
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FIG. 2. Surgical view after left cortical mastoidectomy. A, The cyst was filled with dense keratin flakes extending to the left sigmoid sinus and posterior fossa. The cystic wall was very thin and adherent to the structures. B, Removal of the cyst revealed eroded bony walls of the sigmoid sinus (black arrow) and posterior fossa dura.
Pulsatile tinnitus decreased immediately after the surgery and completely disappeared on the third postoperative day. Pulsatile movement of the left tympanic membrane was not observed at the following visit, and the patient was free of symptoms 5 months postoperatively. DISCUSSION Intradiploic epidermoids represent less than 1% of intracranial tumors, and the temporal bone is rarely involved. Histopathologically, it is indistinguishable from congenital cholesteatoma and is regarded as the same disease. The suggested pathogenesis is erroneous detachment of epithelial remnants from the neural groove between the third and fifth embryonic weeks (1). The usual symptoms are retroauricular pain and/or swelling, neck pain, and dizziness when it involves the temporal bone; this condition could also be found incidentally. A case of epidermoid cyst of the skull with nonpulsatile tinnitus has been reported previously (2). However, to our knowledge, there are no prior reports of intradiploic epidermoid or congenital mastoid cholesteatoma presenting as pulsatile tinnitus.
Pulsatile tinnitus usually originates from either arterial or venous vascular structures. Venous pulsatile tinnitus may originate from stenosis or tortuosity of venous structure or from intracranial hypertension. Recently, growing evidence implicates sigmoid sinus abnormalities, such as diverticulum or dehiscence, as the etiology for the pulsatile tinnitus of venous origin (3). In this case, the epidermoid growth reaching the size enough to compress the sigmoid sinus was suspected to have caused the turbulent flow and the pulsatile tinnitus. Direct transmission of cerebrospinal fluid pulsation through the eroded bony wall of the posterior fossa could be another possible etiology, explaining the pulsatile movement of the tympanic membrane. REFERENCES 1. Ciappetti P, Artico M, Raco A, Gagliardi FM. Intradiploic epidermoid cysts of the skull: report of 10 cases and review of the literature. Acta Neurochir 1990;102:33–7. 2. Piotin M, Gailloud P, Reverdin A, Schneider PA, Pizzolato G, Ru¨fenacht DA. Epidermoid cyst of the skull with nonpulsatile tinnitus. Neuroradiology 1998;40:452–4. 3. Otto KJ, Hudgins PA, Abdelkafy W, Mattox DE. Sigmoid sinus diverticulum: a new surgical approach to the correction of pulsatile tinnitus. Otol Neurotol 2007;28:48–53.
Otology & Neurotology, Vol. 37, No. 5, 2016
Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
Imaging Case of the Month
Intradiploic Epidermoid of Temporal Bone Presenting as Pulsatile Tinnitus Jung Min Lee, Jae Ki Kim, Seong Kyeong Yang, and Joong Keun Kwon Department of Otolaryngology–Head and Neck Surgery, Ulsan University Hospital, Ulsan University College of Medicine, Ulsan, Republic of Korea
Pulsatile tinnitus is characterized by a rhythmic sound that is synchronous with the patient’s heartbeat. Causes of pulsatile tinnitus are various and well documented in the literature. Venous causes of pulsatile tinnitus include a dehiscent jugular bulb, high flow through condylar or mastoid vein, local venous stenosis, idiopathic intracranial hypertension, sigmoid sinus diverticulum or dehiscence, and superior canal dehiscence associated with the superior petrosal sinus. In this case, intradiploic epidermoid caused pulsatile tinnitus by eroding the bony walls of the sigmoid sinus and posterior fossa.
and demonstrated a high signal intensity on T2-weighted imaging (Fig. 1C). Diffusion-weighted MRI showed hyperintensity in the corresponding area consistent with restricted diffusion (Fig. 1D). Transmastoid removal of the mass was performed under general anesthesia on full patient consent. A cystic mass with densely accumulated keratin flakes was observed, which had eroded the bony walls of the sigmoid sinus and posterior fossa, compressing both structures (Fig. 2). The mass reached 2.7 cm in maximal length, and the entire cyst was carefully removed. The exposed sinus and dura were covered with harvested cortical bone dust and tissue glue.
CASE A 50-year-old nonobese woman (body mass index, 22.5) presented with constant left-sided pulsatile tinnitus for 3 months, with no other medical history. She found the symptom increasingly distressing. A full head and neck examination was performed. Otoscopy did not reveal any mass behind clear tympanic membrane, but a pulsatile movement of the posterosuperior quadrant was observed. The tinnitus could not be detected on auscultation over the mastoid, eyes, forehead, or neck. Subjectively, the tinnitus decreased when the patient turned her head to both sides but was not diminished on compression of the ipsilateral jugular vein. Pure-tone audiometry was normal with mild ipsilateral air-bone conduction gap (bone conduction hearing, 9 dB; air conduction hearing, 14 dB). The patient underwent computed tomography (CT) and magnetic resonance imaging (MRI). CT scan revealed a 2-cm mass lesion in the diploic space of the left temporal bone posterior to mastoid air cells. The mass had eroded the mastoid cortex and bony wall over the posterior fossa and sigmoid sinus, compressing the sinus (Fig. 1A). On MRI, the lesion was slightly hyperintense on nonfat saturation T1 (Fig. 1B)
FIG. 1. CT and MRI scans of temporal bone. A, Axial view of CT scan shows left-sided mastoid mass eroding both the mastoid cortex and sigmoid sinus bony wall. B, Axial nonenhanced T1-weighted MR image exhibits some hyperintensity of the mass. C, Corresponding axial T2-weighted image. D, Diffusionweighted image shows focally restricted diffusion in the mass (arrow).
Address correspondence and reprint requests to Joong Keun Kwon, M.D., Department of Otolaryngology–Head and Neck Surgery, Ulsan University Hospital, 290-3 Jeonha-dong, Dong-gu, Ulsan, Republic of Korea; E-mail: [email protected] The authors disclose no conflicts of interest.
e180
Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
INTRADIPLOIC EPIDERMOID OF TEMPORAL BONE
e181
FIG. 2. Surgical view after left cortical mastoidectomy. A, The cyst was filled with dense keratin flakes extending to the left sigmoid sinus and posterior fossa. The cystic wall was very thin and adherent to the structures. B, Removal of the cyst revealed eroded bony walls of the sigmoid sinus (black arrow) and posterior fossa dura.
Pulsatile tinnitus decreased immediately after the surgery and completely disappeared on the third postoperative day. Pulsatile movement of the left tympanic membrane was not observed at the following visit, and the patient was free of symptoms 5 months postoperatively. DISCUSSION Intradiploic epidermoids represent less than 1% of intracranial tumors, and the temporal bone is rarely involved. Histopathologically, it is indistinguishable from congenital cholesteatoma and is regarded as the same disease. The suggested pathogenesis is erroneous detachment of epithelial remnants from the neural groove between the third and fifth embryonic weeks (1). The usual symptoms are retroauricular pain and/or swelling, neck pain, and dizziness when it involves the temporal bone; this condition could also be found incidentally. A case of epidermoid cyst of the skull with nonpulsatile tinnitus has been reported previously (2). However, to our knowledge, there are no prior reports of intradiploic epidermoid or congenital mastoid cholesteatoma presenting as pulsatile tinnitus.
Pulsatile tinnitus usually originates from either arterial or venous vascular structures. Venous pulsatile tinnitus may originate from stenosis or tortuosity of venous structure or from intracranial hypertension. Recently, growing evidence implicates sigmoid sinus abnormalities, such as diverticulum or dehiscence, as the etiology for the pulsatile tinnitus of venous origin (3). In this case, the epidermoid growth reaching the size enough to compress the sigmoid sinus was suspected to have caused the turbulent flow and the pulsatile tinnitus. Direct transmission of cerebrospinal fluid pulsation through the eroded bony wall of the posterior fossa could be another possible etiology, explaining the pulsatile movement of the tympanic membrane. REFERENCES 1. Ciappetti P, Artico M, Raco A, Gagliardi FM. Intradiploic epidermoid cysts of the skull: report of 10 cases and review of the literature. Acta Neurochir 1990;102:33–7. 2. Piotin M, Gailloud P, Reverdin A, Schneider PA, Pizzolato G, Ru¨fenacht DA. Epidermoid cyst of the skull with nonpulsatile tinnitus. Neuroradiology 1998;40:452–4. 3. Otto KJ, Hudgins PA, Abdelkafy W, Mattox DE. Sigmoid sinus diverticulum: a new surgical approach to the correction of pulsatile tinnitus. Otol Neurotol 2007;28:48–53.
Otology & Neurotology, Vol. 37, No. 5, 2016
Copyright © 2016 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited.
