Abstract
An 80 year old man living independently with his wife presented with progressive unsteadiness, generalised weakness and muscle aches over 2 months, following a short episode of flu-like symptoms. Systems review revealed shortness of breath, a hoarse voice, 2kg weight loss and occasional non-drenching night sweats. Bloods showed elevated WCC, CRP and ESR. He was started on 20mg of prednisolone for a working diagnosis of polymyalgia rheumatica. These symptoms did not improve, even after this increased to 30mg. He was admitted to hospital after he developed left leg weakness evolving over the course of 1 day. On examination, he had generalised muscle wasting, no fasciculations, preserved reflexes, left sided foot drop and right sided ulnar nerve palsy. MRI head and spine did not reveal a structural cause. CT thorax-abdomen-pelvis showed no evidence of malignancy, lymphadenopathy or hepatosplenomegaly. An autoimmune screen revealed a strongly positive rheumatoid factor, but negative ANA, ANCA, anti-DSDNA antibodies. A myositis panel and anti-neuronal antibodies were negative. CSF biochemistry showed normal cell count and protein level, with negative oligoclonal bands. Nerve conduction studies suggested a chronic axonal length-dependent peripheral neuropathy and a degree of myopathy. He then developed symmetrical bilateral foot drop and median nerve palsies. FDG-PET-CT showed increased activity within various visualised skeletal muscles- due to either myositis, denervation or physiological changes. Muscle & sural nerve biopsy showed no myositis, but intense inflammation and arterial wall destruction with moderate axonal degeneration suggestive of vasculitic neuropathy. A diagnosis of mononeuritis multiplex caused by tissue-specific vasculitis was made. He received pulsed IV methylprednisolone before starting rituximab. He was discharged when his mobility improved. This case demonstrates that vasculitis can present without rash and mimic polymyalgia rheumatica, which is more common in older patients. Thorough examination and revisiting the diagnosis if steroids do not show improvement is advised.