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Osseous sarcoidosis presenting as a destructive petrous apex lesion
Osseous Sarcoidosis Presenting as a Destructive Petrous Apex Lesion Matthew Ng, MD,* and John K. Niparko, MD† We report a case of sarcoidosis presenting as a destructive petrous apex lesion of the temporal bone. Sarcoidosis is a disease of unknown etiology, featuring granulomatous inflammation in a number of organs and tissues. Osseous involvement of the temporal bone by sarcoidosis is uncommon and rarely encountered clinically. When osseous tissue is involved, it commonly affects the phalangeal bones of the hands and feet with noncaseating granulomas occupying the marrow space and creating a destructive pattern. A similar clinico-pathologic process was found to occur within the petrous apex of the temporal bone in an individual presenting with otalgia, hearing loss, and aural fullness. Imaging of the temporal bones revealed a unilateral destructive lesion of the petrous apex and adjacent skull base. A review of sarcoidosis and petrous apex lesions is presented. Sarcoid involvement of the petrous apex should be considered in the number of pathologies that feature bony destruction of the petrous apex of the temporal bone. (Am J Otolaryngol 2002;23:241-245. Copyright 2002, Elsevier Science (USA). All rights reserved.) (Editorial Comment: This is a great review of sarcoid in general. Because this is a one in a million case, the review is what makes the paper.)
Sarcoidosis is an idiopathic disease featuring granulomatous inflammation in a number of organs and tissues. The clinical presentation largely depends on which organs and tissues in the body are affected. The most common site involved in sarcoidosis is the lungs. Approximately 90% of patients with sarcoidosis will have pulmonary involvement with either bilateral hilar adenopathy or interstitial lung disease. The lymph nodes, eyes, bone marrow, spleen, liver, kidneys, salivary glands, skin, and mucous membranes are all potential sites of involvement. All of these affected sites will contain the characteristic noncaseating granulomas. The etiology of sarcoidosis has yet to be
From the *Department of Otolaryngology—Head and Neck Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA; and the †Department of Otolaryngology—Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, MD. Address correspondence to Matthew Ng, MD, Department of Otolaryngology—Head and Neck Surgery, LAC-USC Medical Center, 1200 North State St, Box 795, Los Angeles, CA 90033. E-mail: [email protected]. Copyright 2002, Elsevier Science (USA). All rights reserved. 0196-0709/02/2304-0001$35.00/0 doi:10.1053/ajot.2002.123457
elucidated. The current thought is that a focal immune response, probably autoimmune, by T-helper lymphocytes (CD4⫹) and mononuclear phagocytic cells develops against a nonspecified antigen.1 This host response evolves into a granuloma. Morphologically, the granuloma contains mononuclear phagocytes (macrophages and giant cells of the Langhans’ type) in the center, surrounded by a rim of mononuclear lymphocytes. As this focal immune response is mounted, general immune function appears to be depressed, as evidenced by leukopenia and skin anergy. Granulomas will occupy each organ involved by sarcoidosis. The granulomas exert their effect when they increase in size and number and disrupt the structural integrity and function of the particular organ. When osseous tissues are involved with sarcoidosis, the granulomatous inflammation is found within the bone marrow, usually in the phalangeal bones of the hands and feet. With the growth of these granulomatous lesions, the bone displays varying degrees of bone destruction, widening of the bone shafts, and attempts at repair with new bone formation. Three levels of bone involvement have been classified based on their radiographic appearance: lytic, permeative, and destructive.2 Osseous sarcoidosis has been also noted less frequently in the marrow space of the long bones of the extremities, ribs, vertebral bod-
American Journal of Otolaryngology, Vol 23, No 4 (July-August), 2002: pp 241-245
241
242
ies, and calvarial skull. There has only been 1 prior report of sarcoidosis in the petrous apex, identified after a MEDLINE literature search (1966 to present). It was noted only as an incidental radiographic finding on computed tomography scan in a patient with other systemic manifestations of sarcoidosis.3,4 CASE REPORT A 50-year-old African American woman presented with complaints of left otalgia, decreased hearing, and left aural fullness for 8 months. These symptoms began when she developed an episode of acute sinusitis. After being treated with antibiotics for the sinusitis, these symptoms temporarily resolved. Two months later, however, she began to experience a recurrence of the same symptoms, but with left tinnitus, dysequilibrium, and vertigo. A community otolaryngologist previously evaluated the patient and placed a ventilation tube for presumed otitis media with effusion, but her symptoms did not improve. The patient denied any previous history of chronic or recurrent ear infections. Review of her past medical history revealed a history of sarcoidosis, diagnosed in 1981 after a chest radiograph revealed bilateral hilar adenopathy. She underwent mediastinoscopy with biopsy of the enlarged lymph nodes, which confirmed the diagnosis of sarcoidosis. She was not treated for the sarcoidosis until 6 years later when she developed colitis related to the sarcoidosis. She was placed on oral glucocorticosteroid therapy for 3 months. Since then, she was considered to be “in remission.” She denied having any known malignancies. An audiogram revealed an asymmetric, high-frequency, sensorineural hearing loss in the left ear, with normal auditory thresholds between 250 Hz to 2 kHz, but hearing loss that progressed from mild to moderately severe levels between 2 kHz and 8 KHz. She had normal auditory thresholds in the right contralateral ear at the standard test frequencies. Speech recognition scores were 100% bilaterally. These audiometric findings prompted a magnetic resonance imaging study to rule out a retrocochlear cause for the hearing loss. A homogeneously enhancing mass was located in the left petrous apex and clival region, with erosion of the medial wall of the carotid canal.
NG AND NIPARKO
The petrous carotid artery was mildly effaced. This erosive process extended posteriorly to involve the left foramen rotundum and the jugular canal inferiorly. The brainstem, the cerebellopontine angle, and the VIIth and VIIIth nerve complex appeared normal and without any signal enhancement. Computed tomography imaging of her temporal bones confirmed a 2.5 ⫻ 2 cm irregularly destructive lesion of the petrous apex extending into the clivus, located anterior to the internal auditory canal and medial to the carotid canal (Figs 1 and 2). Extension of this erosive process was noted toward the region of Meckel’s cave. Physical examination of the patient revealed normal otomicroscopic findings with an aerated middle ear space. No cervical lymphadenopathy was palpated. Cranial nerve examination suggested decreased sensation in the maxillary division of the trigeminal nerve distribution. No oculomotor deficits were noted. A transmastoid infralabyrinthine approach to the petrous apex was taken to retrieve diagnostic material. While removing the bone bordered superiorly by the basal turn of the cochlea, inferiorly by the jugular bulb, and anteriorly by the carotid artery, exuberant and friable granulation tissue was encountered.
Fig 1. Axial computed tomography scan through the left petrous apex demonstrating a lytic bony lesion. Note extension of erosion into clivus.
PETROUS APEX SARCOIDOSIS
Fig 2. Coronal computed tomography scan through the left petrous apex demonstrating a lytic bony lesion.
Frozen section analysis demonstrated granulomas and inflammation, but the granulomas did not possess any malignant cytologic features. To promote aeration of the area, the bony window into the petrous apex bordered by the above 3 structures was widened by additional bone removal without violation of the anatomical structures. Final pathologic diagnosis from the permanent specimen revealed tissue containing noncaseating granulomas, consistent with sarcoidosis. An acidfast stain for Mycobacterium tuberculosis was negative. Postoperatively, the patient was treated at the Sarcoid Clinic at the Johns Hopkins Hospital, where she completed a 6-month course of oral prednisone starting at 20 mg per day. Serial computed tomography imaging of the temporal bone at 6 months and 1 year demonstrated a stable and nonprogressive lesion in the petrous apex. DISCUSSION The petrous bone is 1 of the 4 bones that constitute the temporal bone, along with the tympanic, squamous, and mastoid bones. It contains the otic capsule and the petrous segment of the carotid artery. The petrous apex of the petrous bone is situated anterior to the otic capsule and the internal auditory canal. Its
243
pyramidal shape has the petrous ridge forming the apex. The petrous apex is located anteromedially, abutting the clivus medially and the body and the greater wing of the sphenoid bone anteriorly. It forms the anterior floor of the middle cranial fossa. Commonly encountered lesions of the petrous apex include cholesterol granuloma and cholesteatomas. Cholesterol granulomas result from a host response to blood breakdown products, particularly hemosiderin, presumably from a bleed that results after obstruction of the air-containing spaces within the petrous apex. Such a reaction incites a foreignbody response with expansile and destructive properties. Cholesteatomas, or epidermoids, are epithelially lined cysts, either congenital or acquired, that may be found in the petrous apex. They also create a destructive pattern with the growth of the lesion. A host of other lesions that originate both from the petrous apex or extend into the petrous apex from contiguous areas may create a destructive outcome. A list of such lesions is found in Table 1. Sarcoidosis within the petrous apex has been previously reported only as an incidental radiographic finding in one patient.3,4 This patient was newly diagnosed with sarcoidosis after mediastinoscopy and biopsy of the hilar lymph nodes had demonstrated the typical histologic features. The patient had a concurrent frontal calvarial bone lytic lesion that was biopsied and displayed the typical noncaseating granulomas. The destructive lesion in the petrous apex was not biopsied because of its relatively inaccessible location. Therefore, the diagnosis of petrous sarcoidosis in this 1 case was inferred from the patient’s clinical picture. The patient had no symptoms referable to the inner ear. In the present case, the patient presented with an asymmetric hearing loss, aural fullness, and ear pain. These symptoms prompted imaging of the temporal bone and posterior fossa. Because of the bony destructive pattern in the petrous apex and adjacent skull base, a malignant lesion was suspected and a biopsy was carried out. Signal characteristics of the magnetic resonance imaging did not readily suggest the presence of a cholesterol granuloma or cholesteatoma. Because sarcoidosis was rare in the area and because the patient’s
244
NG AND NIPARKO
TABLE 1. Lesions of the Petrous Apex Infectious ● Petrous apicitis ● Skull base osteomyelitis/malignant otitis externa Benign ● Mucocele/mucus retention cyst ● Cholesterol granuloma ● Cholesteatoma (primary or acquired) ● Arachnoid cyst ● Sarcoidosis Malignant ● Metastases (breast, lung, kidney, prostate gland) Osteodystrophy (Paget’s disease, fibrous dysplasia, osteopetrosis) Vascular ● Aneurysm of petrous internal carotid artery Lesions extending into petrous apex from contiguous areas: ● Schwannoma (cranial nerves IX-XI with extension into petrous apex) ● Meningioma (eg, petroclival meningioma with extension into petrous apex) ● Chordoma (arises from clivus with spread to petrous apex) ● Chondroma/chondrosarcoma (with lateral extension into petrous apex) ● Endolymphatic sac tumor/papillary adenomatous tumors (with extension into petrous apex) ● Nasopharyngeal carcinoma (with extension to petrous apex through petro-occipital fissure) ● Rhabdomyosarcoma ● Paraganglioma/glomus jugulare tumor
sarcoidosis had been in remission for 12 years, the possibility that this lesion represented a continuation of the sarcoidosis was not immediately considered. The granulomas of osseous sarcoidosis typically reside in the bone marrow. The petrous apex is pneumatized in approximately 30% of temporal bones5; therefore, in the remaining cases the petrous apex contains bone marrow, where it may be a potential focus for granuloma deposition by sarcoidosis. In the present case, bone destruction was also noted in the adjacent clivus, which is marrow-filled as well. Any medullary bone in the skull base may be a potential site for involvement by sarcoidosis. Because the skull base originates from both intramembranous and endochondral types of bone formation, the bone from the former type of bone development will contain bone marrow. Interestingly, a report of skull base sarcoidosis in the planum sphenoidale and greater wing of the sphenoid bone that caused progressive blindness appeared recently in the neurosurgical literature.6 The erosive changes within the medullary bone result from growth of the noncaseating granulomas and gradual replacement of the marrow space. The cortex of the bone thins and expands. Local production of chemical mediators such as lysozyme, elastase, collagenase, and protease contribute to the bone de-
struction.2 The host attempts a reparative response with new bone formation. Osseous sarcoidosis occurs at a frequency of 1% to 13% in patients with sarcoidosis.2 It is usually found in the setting of chronic sarcoidosis.2 This was indeed the case when sarcoidosis was diagnosed 18 years before our patient’s presentation with the petrous apex lesion. There had been no recent manifestations of the disease, which had been quiescent for nearly 12 years. On the same lines, osseous sarcoidosis is rarely the sole manifestation of sarcoidosis. Other organ systems are usually affected before bone. One common feature of osseous sarcoidosis which was not observed in our present case was the fact that osseous sarcoidosis usually occurs with skin lesions. These skin lesions may be in the form of lupus pernio, subcutaneous nodules, or erythema nodosum. In one study, up to 71% of the patients with osseous sarcoidosis concurrently had skin lesions.2 The question arose as to whether the destructive process in the petrous apex alone could have accounted for the patient’s hearing loss, aural fullness, and tinnitus. In all the imaging sequences, the otic capsule appeared intact and was not violated by the erosive process. Hence, the possibility of neurosarcoidosis was entertained. Neurosarcoidosis occurs in about 5% of pa-
PETROUS APEX SARCOIDOSIS
tients with sarcoidosis.6 It is usually encountered early in the disease process. Susceptible sites include the cranial nerves, meninges, hypothalamus, and pituitary gland. Basal granulomatous meningitis has been suggested to be the mechanism responsible for most of the cranial neuropathies.6 When cranial nerves are affected, the most commonly afflicted nerve is the facial nerve, followed by the optic nerve, the glossopharyngeal and vagus nerves, and then the cochlear nerve.7 The hearing loss associated with sarcoidosis is sensorineural, sometimes fluctuating,8 varying from unilateral to bilateral and from mild to severe, and can affect the high or low frequencies.9 Vestibular loss has also been noted in several reports.10,11 Babin et al provided the first histologic evidence for involvement of the auditory nerve in a patient with sarcoidosis and hearing loss.12 A perivascular lymphocytic infiltrate (vasculitis) was seen around the cochlear, vestibular, and facial nerves within the internal auditory canal. It is possible that neurosarcoidosis may have been responsible for the hearing loss and other auditory symptoms in our patient but was not detected on the magnetic resonance imaging scan. We would have expected to observe some enhancement or thickening of the acousticofacial bundle if vasculitis or granulomatous neuritis was present. Furthermore, the meninges did not demonstrate any enhancement as is normally seen in neurosarcoidosis.13,14 The customary treatment for osseous sarcoidosis, as well as for neurosarcoidosis, is oral corticosteroids. The rationale behind this type of therapy is to reduce inflammation within the tissues, blunt the focal immune response, and halt the progression of the disease. After 6 months on oral steroids, our patient’s symptoms resolved, and there was no additional bone destruction in the petrous apex on subsequent imaging studies. There have yet been no established guidelines for the length of treatment and endpoint of ther-
245
apy with steroids. Furthermore, no one knows the length of time serial imaging should continue. It appears that our patient’s petrous apex lesion has been held at bay, and interval imaging semiannually will help detect any progression of the disease. Osseous sarcoidosis should be added to the long list of causes that can present with petrous apex destruction. This should be a serious consideration, especially if the patient has a history of sarcoidosis, however remote, and is experiencing neurotologic symptoms. An active search for both osseous sarcoidosis and neurosarcoidosis should then be instigated. REFERENCES 1. Crystal RG: Sarcoidosis, in: Braunwald E, Fauci AS, Kasper DL, et al (eds): Harrison’s Principles of Internal Medicine (ed 15). New York, NY, McGraw-Hill, 2001, pp 1969-1971 2. Neville E, Carstairs LS, James DG: Bone sarcoidosis. Ann N Y Acad Sci 278:475-487, 1976 3. Dalley RW, Robertson WD, Nugent RA: Computed tomography of calvarial and petrous bone sarcoidosis. J Comput Assist Tomogr 115:884-886, 1987 4. Perry TL, Road JD, Sisler WJ: Sarcoidosis of the frontal and petrous temporal bones. Br J Hosp Med 51: 293-294, 1994 5. Myerson MC, Rubin J, Gilbert JG: Anatomic studies of the petrous portion of the temporal bone. Arch Otolaryngol 20:195-210, 1934 6. Dare AO, Lopes DK, Grand W: Sphenoid wing sarcoidosis. J Neurosurg 94:849, 2001 7. Delaney P: Neurologic manifestations in sarcoidosis. Review of the literature, with a report of 23 cases. Ann Int Med 87:336-345, 1977 8. Jahrsdoerfer RA, Thompson EG, Johns MME, et al: Sarcoidosis and fluctuating hearing loss. Ann Otol Rhinol Laryngol 90:161-163, 1981 9. Majumdar B, Crowther J: Hearing loss in sarcoidosis. J Laryngol Otol 97:635-639, 1983 10. Hybels RL, Rice DH: Neuro-otologic manifestations of sarcoidosis. Laryngoscope 86:1873-1878, 1976 11. Von Brevern M, Lempert T, Bronstein AM, et al: Selective vestibular damage in neurosarcoidosis. Ann Neurol 42:117-120, 1997 12. Babin RW, Liu C, Aschenbrener C: Histopathology of neurosensory deafness in sarcoidosis. Ann Otol Rhinol Laryngol 93:389-393, 1984 13. Hayes WS, Sherman JL, Stern BJ, et al: MR and CT evaluation of intracranial sarcoidosis. Am J Roentgenol 149:1043-1049, 1987 14. Ketonen L, Oksanen V, Kuuliaha I: Preliminary experience of magnetic resonance imaging in neurosarcoidosis. Neuroradiology 29:127-129, 1987
Sarcoidosis is an idiopathic disease featuring granulomatous inflammation in a number of organs and tissues. The clinical presentation largely depends on which organs and tissues in the body are affected. The most common site involved in sarcoidosis is the lungs. Approximately 90% of patients with sarcoidosis will have pulmonary involvement with either bilateral hilar adenopathy or interstitial lung disease. The lymph nodes, eyes, bone marrow, spleen, liver, kidneys, salivary glands, skin, and mucous membranes are all potential sites of involvement. All of these affected sites will contain the characteristic noncaseating granulomas. The etiology of sarcoidosis has yet to be
From the *Department of Otolaryngology—Head and Neck Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA; and the †Department of Otolaryngology—Head and Neck Surgery, Johns Hopkins Medical Institutions, Baltimore, MD. Address correspondence to Matthew Ng, MD, Department of Otolaryngology—Head and Neck Surgery, LAC-USC Medical Center, 1200 North State St, Box 795, Los Angeles, CA 90033. E-mail: [email protected]. Copyright 2002, Elsevier Science (USA). All rights reserved. 0196-0709/02/2304-0001$35.00/0 doi:10.1053/ajot.2002.123457
elucidated. The current thought is that a focal immune response, probably autoimmune, by T-helper lymphocytes (CD4⫹) and mononuclear phagocytic cells develops against a nonspecified antigen.1 This host response evolves into a granuloma. Morphologically, the granuloma contains mononuclear phagocytes (macrophages and giant cells of the Langhans’ type) in the center, surrounded by a rim of mononuclear lymphocytes. As this focal immune response is mounted, general immune function appears to be depressed, as evidenced by leukopenia and skin anergy. Granulomas will occupy each organ involved by sarcoidosis. The granulomas exert their effect when they increase in size and number and disrupt the structural integrity and function of the particular organ. When osseous tissues are involved with sarcoidosis, the granulomatous inflammation is found within the bone marrow, usually in the phalangeal bones of the hands and feet. With the growth of these granulomatous lesions, the bone displays varying degrees of bone destruction, widening of the bone shafts, and attempts at repair with new bone formation. Three levels of bone involvement have been classified based on their radiographic appearance: lytic, permeative, and destructive.2 Osseous sarcoidosis has been also noted less frequently in the marrow space of the long bones of the extremities, ribs, vertebral bod-
American Journal of Otolaryngology, Vol 23, No 4 (July-August), 2002: pp 241-245
241
242
ies, and calvarial skull. There has only been 1 prior report of sarcoidosis in the petrous apex, identified after a MEDLINE literature search (1966 to present). It was noted only as an incidental radiographic finding on computed tomography scan in a patient with other systemic manifestations of sarcoidosis.3,4 CASE REPORT A 50-year-old African American woman presented with complaints of left otalgia, decreased hearing, and left aural fullness for 8 months. These symptoms began when she developed an episode of acute sinusitis. After being treated with antibiotics for the sinusitis, these symptoms temporarily resolved. Two months later, however, she began to experience a recurrence of the same symptoms, but with left tinnitus, dysequilibrium, and vertigo. A community otolaryngologist previously evaluated the patient and placed a ventilation tube for presumed otitis media with effusion, but her symptoms did not improve. The patient denied any previous history of chronic or recurrent ear infections. Review of her past medical history revealed a history of sarcoidosis, diagnosed in 1981 after a chest radiograph revealed bilateral hilar adenopathy. She underwent mediastinoscopy with biopsy of the enlarged lymph nodes, which confirmed the diagnosis of sarcoidosis. She was not treated for the sarcoidosis until 6 years later when she developed colitis related to the sarcoidosis. She was placed on oral glucocorticosteroid therapy for 3 months. Since then, she was considered to be “in remission.” She denied having any known malignancies. An audiogram revealed an asymmetric, high-frequency, sensorineural hearing loss in the left ear, with normal auditory thresholds between 250 Hz to 2 kHz, but hearing loss that progressed from mild to moderately severe levels between 2 kHz and 8 KHz. She had normal auditory thresholds in the right contralateral ear at the standard test frequencies. Speech recognition scores were 100% bilaterally. These audiometric findings prompted a magnetic resonance imaging study to rule out a retrocochlear cause for the hearing loss. A homogeneously enhancing mass was located in the left petrous apex and clival region, with erosion of the medial wall of the carotid canal.
NG AND NIPARKO
The petrous carotid artery was mildly effaced. This erosive process extended posteriorly to involve the left foramen rotundum and the jugular canal inferiorly. The brainstem, the cerebellopontine angle, and the VIIth and VIIIth nerve complex appeared normal and without any signal enhancement. Computed tomography imaging of her temporal bones confirmed a 2.5 ⫻ 2 cm irregularly destructive lesion of the petrous apex extending into the clivus, located anterior to the internal auditory canal and medial to the carotid canal (Figs 1 and 2). Extension of this erosive process was noted toward the region of Meckel’s cave. Physical examination of the patient revealed normal otomicroscopic findings with an aerated middle ear space. No cervical lymphadenopathy was palpated. Cranial nerve examination suggested decreased sensation in the maxillary division of the trigeminal nerve distribution. No oculomotor deficits were noted. A transmastoid infralabyrinthine approach to the petrous apex was taken to retrieve diagnostic material. While removing the bone bordered superiorly by the basal turn of the cochlea, inferiorly by the jugular bulb, and anteriorly by the carotid artery, exuberant and friable granulation tissue was encountered.
Fig 1. Axial computed tomography scan through the left petrous apex demonstrating a lytic bony lesion. Note extension of erosion into clivus.
PETROUS APEX SARCOIDOSIS
Fig 2. Coronal computed tomography scan through the left petrous apex demonstrating a lytic bony lesion.
Frozen section analysis demonstrated granulomas and inflammation, but the granulomas did not possess any malignant cytologic features. To promote aeration of the area, the bony window into the petrous apex bordered by the above 3 structures was widened by additional bone removal without violation of the anatomical structures. Final pathologic diagnosis from the permanent specimen revealed tissue containing noncaseating granulomas, consistent with sarcoidosis. An acidfast stain for Mycobacterium tuberculosis was negative. Postoperatively, the patient was treated at the Sarcoid Clinic at the Johns Hopkins Hospital, where she completed a 6-month course of oral prednisone starting at 20 mg per day. Serial computed tomography imaging of the temporal bone at 6 months and 1 year demonstrated a stable and nonprogressive lesion in the petrous apex. DISCUSSION The petrous bone is 1 of the 4 bones that constitute the temporal bone, along with the tympanic, squamous, and mastoid bones. It contains the otic capsule and the petrous segment of the carotid artery. The petrous apex of the petrous bone is situated anterior to the otic capsule and the internal auditory canal. Its
243
pyramidal shape has the petrous ridge forming the apex. The petrous apex is located anteromedially, abutting the clivus medially and the body and the greater wing of the sphenoid bone anteriorly. It forms the anterior floor of the middle cranial fossa. Commonly encountered lesions of the petrous apex include cholesterol granuloma and cholesteatomas. Cholesterol granulomas result from a host response to blood breakdown products, particularly hemosiderin, presumably from a bleed that results after obstruction of the air-containing spaces within the petrous apex. Such a reaction incites a foreignbody response with expansile and destructive properties. Cholesteatomas, or epidermoids, are epithelially lined cysts, either congenital or acquired, that may be found in the petrous apex. They also create a destructive pattern with the growth of the lesion. A host of other lesions that originate both from the petrous apex or extend into the petrous apex from contiguous areas may create a destructive outcome. A list of such lesions is found in Table 1. Sarcoidosis within the petrous apex has been previously reported only as an incidental radiographic finding in one patient.3,4 This patient was newly diagnosed with sarcoidosis after mediastinoscopy and biopsy of the hilar lymph nodes had demonstrated the typical histologic features. The patient had a concurrent frontal calvarial bone lytic lesion that was biopsied and displayed the typical noncaseating granulomas. The destructive lesion in the petrous apex was not biopsied because of its relatively inaccessible location. Therefore, the diagnosis of petrous sarcoidosis in this 1 case was inferred from the patient’s clinical picture. The patient had no symptoms referable to the inner ear. In the present case, the patient presented with an asymmetric hearing loss, aural fullness, and ear pain. These symptoms prompted imaging of the temporal bone and posterior fossa. Because of the bony destructive pattern in the petrous apex and adjacent skull base, a malignant lesion was suspected and a biopsy was carried out. Signal characteristics of the magnetic resonance imaging did not readily suggest the presence of a cholesterol granuloma or cholesteatoma. Because sarcoidosis was rare in the area and because the patient’s
244
NG AND NIPARKO
TABLE 1. Lesions of the Petrous Apex Infectious ● Petrous apicitis ● Skull base osteomyelitis/malignant otitis externa Benign ● Mucocele/mucus retention cyst ● Cholesterol granuloma ● Cholesteatoma (primary or acquired) ● Arachnoid cyst ● Sarcoidosis Malignant ● Metastases (breast, lung, kidney, prostate gland) Osteodystrophy (Paget’s disease, fibrous dysplasia, osteopetrosis) Vascular ● Aneurysm of petrous internal carotid artery Lesions extending into petrous apex from contiguous areas: ● Schwannoma (cranial nerves IX-XI with extension into petrous apex) ● Meningioma (eg, petroclival meningioma with extension into petrous apex) ● Chordoma (arises from clivus with spread to petrous apex) ● Chondroma/chondrosarcoma (with lateral extension into petrous apex) ● Endolymphatic sac tumor/papillary adenomatous tumors (with extension into petrous apex) ● Nasopharyngeal carcinoma (with extension to petrous apex through petro-occipital fissure) ● Rhabdomyosarcoma ● Paraganglioma/glomus jugulare tumor
sarcoidosis had been in remission for 12 years, the possibility that this lesion represented a continuation of the sarcoidosis was not immediately considered. The granulomas of osseous sarcoidosis typically reside in the bone marrow. The petrous apex is pneumatized in approximately 30% of temporal bones5; therefore, in the remaining cases the petrous apex contains bone marrow, where it may be a potential focus for granuloma deposition by sarcoidosis. In the present case, bone destruction was also noted in the adjacent clivus, which is marrow-filled as well. Any medullary bone in the skull base may be a potential site for involvement by sarcoidosis. Because the skull base originates from both intramembranous and endochondral types of bone formation, the bone from the former type of bone development will contain bone marrow. Interestingly, a report of skull base sarcoidosis in the planum sphenoidale and greater wing of the sphenoid bone that caused progressive blindness appeared recently in the neurosurgical literature.6 The erosive changes within the medullary bone result from growth of the noncaseating granulomas and gradual replacement of the marrow space. The cortex of the bone thins and expands. Local production of chemical mediators such as lysozyme, elastase, collagenase, and protease contribute to the bone de-
struction.2 The host attempts a reparative response with new bone formation. Osseous sarcoidosis occurs at a frequency of 1% to 13% in patients with sarcoidosis.2 It is usually found in the setting of chronic sarcoidosis.2 This was indeed the case when sarcoidosis was diagnosed 18 years before our patient’s presentation with the petrous apex lesion. There had been no recent manifestations of the disease, which had been quiescent for nearly 12 years. On the same lines, osseous sarcoidosis is rarely the sole manifestation of sarcoidosis. Other organ systems are usually affected before bone. One common feature of osseous sarcoidosis which was not observed in our present case was the fact that osseous sarcoidosis usually occurs with skin lesions. These skin lesions may be in the form of lupus pernio, subcutaneous nodules, or erythema nodosum. In one study, up to 71% of the patients with osseous sarcoidosis concurrently had skin lesions.2 The question arose as to whether the destructive process in the petrous apex alone could have accounted for the patient’s hearing loss, aural fullness, and tinnitus. In all the imaging sequences, the otic capsule appeared intact and was not violated by the erosive process. Hence, the possibility of neurosarcoidosis was entertained. Neurosarcoidosis occurs in about 5% of pa-
PETROUS APEX SARCOIDOSIS
tients with sarcoidosis.6 It is usually encountered early in the disease process. Susceptible sites include the cranial nerves, meninges, hypothalamus, and pituitary gland. Basal granulomatous meningitis has been suggested to be the mechanism responsible for most of the cranial neuropathies.6 When cranial nerves are affected, the most commonly afflicted nerve is the facial nerve, followed by the optic nerve, the glossopharyngeal and vagus nerves, and then the cochlear nerve.7 The hearing loss associated with sarcoidosis is sensorineural, sometimes fluctuating,8 varying from unilateral to bilateral and from mild to severe, and can affect the high or low frequencies.9 Vestibular loss has also been noted in several reports.10,11 Babin et al provided the first histologic evidence for involvement of the auditory nerve in a patient with sarcoidosis and hearing loss.12 A perivascular lymphocytic infiltrate (vasculitis) was seen around the cochlear, vestibular, and facial nerves within the internal auditory canal. It is possible that neurosarcoidosis may have been responsible for the hearing loss and other auditory symptoms in our patient but was not detected on the magnetic resonance imaging scan. We would have expected to observe some enhancement or thickening of the acousticofacial bundle if vasculitis or granulomatous neuritis was present. Furthermore, the meninges did not demonstrate any enhancement as is normally seen in neurosarcoidosis.13,14 The customary treatment for osseous sarcoidosis, as well as for neurosarcoidosis, is oral corticosteroids. The rationale behind this type of therapy is to reduce inflammation within the tissues, blunt the focal immune response, and halt the progression of the disease. After 6 months on oral steroids, our patient’s symptoms resolved, and there was no additional bone destruction in the petrous apex on subsequent imaging studies. There have yet been no established guidelines for the length of treatment and endpoint of ther-
245
apy with steroids. Furthermore, no one knows the length of time serial imaging should continue. It appears that our patient’s petrous apex lesion has been held at bay, and interval imaging semiannually will help detect any progression of the disease. Osseous sarcoidosis should be added to the long list of causes that can present with petrous apex destruction. This should be a serious consideration, especially if the patient has a history of sarcoidosis, however remote, and is experiencing neurotologic symptoms. An active search for both osseous sarcoidosis and neurosarcoidosis should then be instigated. REFERENCES 1. Crystal RG: Sarcoidosis, in: Braunwald E, Fauci AS, Kasper DL, et al (eds): Harrison’s Principles of Internal Medicine (ed 15). New York, NY, McGraw-Hill, 2001, pp 1969-1971 2. Neville E, Carstairs LS, James DG: Bone sarcoidosis. Ann N Y Acad Sci 278:475-487, 1976 3. Dalley RW, Robertson WD, Nugent RA: Computed tomography of calvarial and petrous bone sarcoidosis. J Comput Assist Tomogr 115:884-886, 1987 4. Perry TL, Road JD, Sisler WJ: Sarcoidosis of the frontal and petrous temporal bones. Br J Hosp Med 51: 293-294, 1994 5. Myerson MC, Rubin J, Gilbert JG: Anatomic studies of the petrous portion of the temporal bone. Arch Otolaryngol 20:195-210, 1934 6. Dare AO, Lopes DK, Grand W: Sphenoid wing sarcoidosis. J Neurosurg 94:849, 2001 7. Delaney P: Neurologic manifestations in sarcoidosis. Review of the literature, with a report of 23 cases. Ann Int Med 87:336-345, 1977 8. Jahrsdoerfer RA, Thompson EG, Johns MME, et al: Sarcoidosis and fluctuating hearing loss. Ann Otol Rhinol Laryngol 90:161-163, 1981 9. Majumdar B, Crowther J: Hearing loss in sarcoidosis. J Laryngol Otol 97:635-639, 1983 10. Hybels RL, Rice DH: Neuro-otologic manifestations of sarcoidosis. Laryngoscope 86:1873-1878, 1976 11. Von Brevern M, Lempert T, Bronstein AM, et al: Selective vestibular damage in neurosarcoidosis. Ann Neurol 42:117-120, 1997 12. Babin RW, Liu C, Aschenbrener C: Histopathology of neurosensory deafness in sarcoidosis. Ann Otol Rhinol Laryngol 93:389-393, 1984 13. Hayes WS, Sherman JL, Stern BJ, et al: MR and CT evaluation of intracranial sarcoidosis. Am J Roentgenol 149:1043-1049, 1987 14. Ketonen L, Oksanen V, Kuuliaha I: Preliminary experience of magnetic resonance imaging in neurosarcoidosis. Neuroradiology 29:127-129, 1987