Antineutrophil Cytoplasmic Antibody Vasculitis Causing Skull Base Inflammation and Aortitis.

Sir,

A 70-year-old female was admitted with sudden-onset bilateral hearing loss followed 2 weeks later by severe pain in both angles of the jaw, paresthesia of tongue, ageusia, sinonasal congestion, and vertex headache. She had a history of systemic hypertension and diabetes mellitus. On evaluation, she was afebrile and had a normal external ear canal, bilateral severe sensorineural hearing loss, and temporal bone tenderness bilaterally. Magnetic resonance imaging (MRI) showed T2 opacification with contrast enhancement of both middle-ear cavities as well as symmetric contrast enhancement of the basal and middle turns of both cochlea [Figure 1]. The 7th and 8th nerve complex within the internal auditory canals was normal. Her erythrocyte sedimentation rate (ESR) was 105 mm/h, and P-antineutrophil cytoplasmic antibody (ANCA) by IF and anti-myeloperoxidase (MPO) by ELISA was positive (23.2 U/L).

Figure 1

Magnetic resonance imaging; left panel; T2 weighted images of both middle ear cavities show T2 hyperintense opacification with contrast enhancement, suggesting inflammation/infection. Right panel; T1 contrast magnetic resonance imaging; symmetric contrast enhancement in the basal and middle turns of both cochlea and to mild degree in the vestibule and left sided posterior semicircular canal [blue arrows]

Positron emission tomography-computed tomography (PET-CT) and three-phase bone scan showed avid uptake suggestive of inflammation in bilateral middle-ear cavities, petrous temporal bones, mastoid regions, and left torus tubarius without bone erosion [Figure 2]. Fluorodeoxyglucose PET also showed circumferential wall thickening in the right brachiocephalic artery, arch of the aorta, infrarenal abdominal aorta, distal abdominal aorta, and left common iliac artery suggestive of diffuse aortitis. She refused a biopsy of the skull base lesion. Based on this, she was diagnosed with ANCA vasculitis with skull base inflammation and aortitis. She was started on intravenous methylprednisolone 1 g/day × 5 days, followed by combination therapy with oral prednisolone and mycophenolate mofetil 2 g/day for 2 months. Her hearing improved by 30 decibels and her headache resolved in 2 months. She is on maintenance immunosuppression with steroids and mycophenolate.

Figure 2

Positron emission tomography-computed tomography images; (a and b) increased fluorodeoxyglucose uptake noted in the opacification of bilateral mastoid air cells and middle-ear cavities and in the prominent left torus tubarius in the nasopharynx. (c) Fluorodeoxyglucose avid wall thickening in infra-renal abdominal aorta (short segment), distal abdominal aorta, and left common iliac artery. (d) Circumferential wall thickening in the arch of the aorta. (e) Circumferential fluorodeoxyglucose avid wall thickening of the right brachiocephalic artery

Skull base osteomyelitis (SBO) is a devastating condition often seen in diabetics. It presents with headache, cranial neuropathy, elevated ESR, and abnormal temporal bone or clival imaging findings.[1] Biopsy is often required for diagnosis as SBO can be caused by infection, inflammation, or malignancy. Classic malignant otitis externa occurs from spread of infection from the external auditory canal to the temporal bone, whereas central skull base osteomyelitis (CSBO) often centers on the clivus and spreads to the sphenoid or occiput.[2] CSBO is not often accompanied by external or middle-ear granulation tissue and is more indolent. CT and MRI are less useful as imaging abnormalities occur late. MRI change includes diffuse clival hypointensity on T1-weighted images relative to normal fatty marrow and pre- and paraclival soft-tissue infiltration with obliteration of normal fat planes or soft-tissue masses.[1] PET-CT/single-photon emission computed tomography and bone scans can be useful for the diagnosis and targeting a site for biopsy.[3] Wegener's granulomatosis (now known as granulomatosis with polyangiitis [GPA]) can involve the skull base and mimic SBO.[45]

Aortitis is an inflammation affecting the wall of the aorta. Unlike normal myocardium which can accumulate radiotracer, aortic wall uptake is always abnormal and indicative of aortitis, either inflammation or infection. Large-vessel vasculitis, such as Takayasu's arteritis (TA) and giant cell arteritis, is the most common noninfectious cause of aortitis. GPA with ANCA vasculitis is a very rare cause of aortitis as it typically involves small- and medium-sized vasculitis.[67]

In contrast to the predominantly stenotic complications of TA, ANCA-associated aortitis is often accompanied by perivasculitis and dissection due to vasa vasorum vasculitis of the aorta and its major branches; causing perivascular soft-tissue masses, aneurysms, dissection, and rupture.[8] C-ANCA is more commonly associated with aortitis than P-ANCA.[9]

Although GPA is primarily associated with PR3-ANCA (C-ANCA) and microscopic polyangiitis with MPO-ANCA (P-ANCA), cross-reactivity, double seropositivity, or even ANCA negativity can occur in around 10%–20% of these patients.[10]

In our patient, PET-CT disclosed concurrent skull base lesions and aortitis in the context of P-ANCA antibodies. This unusual combination has not been reported earlier.

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Conflicts of interest

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