Granulomatosis with polyangitis with hypertrophic pachymeningitis manifesting as low T2 signal on MRI

A 32-year-old male patient with longstanding granulomatosis with polyangitis (GPA) presented with chronic headache.

MRI head was performed in order to further evaluate his symptoms. MRI head showed hypertrophic pachymeninges (HPM) with low T1 and T2 signal. Low T2 signal has not been previously described in GPA patients with HPM.

Granulomatosis with polyangitis (GPA), previously known as Wegener’s granulomatosis, is a multisystemic vasculitis typically affecting small and medium vessels. The classic triad of GPA include rhinitis, pulmonary involvement secondary to granulomatous lesions and renal failure secondary to glomerulonephritis commonly associated with crescent formation [1]. While previous studies have reported neurological manifestations occurring between 22-54% of GPA patients, this commonly resulted in peripheral or cranial neuropathy. The incidence of cerebral and meningeal involvement is much rarer affecting between 2-8% of patients [1].

There are three different patterns of disease which have been proposed by Drachman et al. in relation to the neuro-radiological manifestations of GPA [2, 3]. Firstly, small vessel vasculitis leading to infarcts or haemorrhages. The second pattern is extra-cranial granulomatous formation commonly originating from sinonasal or para-nasal mucosa leading to bony destruction and subsequent extension into the meninges. Thirdly, primary intracranial granuloma formation in the skull, meninges or brain parenchyma.

Another important neuro-radiological finding of GPA is hypertrophic pachymeningitis (HPM). HPM refers to fibrosing inflammation of the dura mater [2]. While HPM may be idiopathic, it is important to exclude secondary causes as described below [2]. While previous studies [1, 4] have demonstrated HPM in GPA using contrast-enhanced T1-weighted MR imaging, our case is novel as it shows HPM in GPA can also be demonstrated as low signal on T2-weighted MRI sequences and this is to our knowledge the first time it has been described and published. High dose intravenous glucocorticoids and cyclophosphamide have been used in the treatment of HPM secondary to GPA with the aim of inducing remission [2, 4].

GPA causing central nervous system (CNS) disease involvement is commonly associated with a refractory disease course, hence early radiological diagnosis can prompt clinicians to consider early treatment thereby reducing patient morbidity [5]. The current case demonstrates how HPM in patients with GPA can be demonstrated as low signal T2 weighted MRI.