Isolated Lower Limb Vasculitis Following SARS-CoV-2 Infection: A Case Report.

Vasculitis is an autoimmune disease defined by inflammation within blood vessels, typically manifesting systemically with multi-organ complications and clinical features. Isolated vasculitis itself, however, is extremely rare and not characteristically based on the pathophysiology of the condition. Whilst there have been cases of isolated vasculitis in large-medium vessels (e.g. the aorta, subclavian, axillary, and/or femoral arteries) documented in the literature, vasculitis isolated to medium to smaller vessels is much more infrequent and is the primary focus of the following case report. We present a case of a 70-year-old male three weeks post-severe acute respiratory syndrome coronavirus 2, presenting with nausea, loss of appetite, eight kilograms of weight loss, and bilateral anterior knee pain resulting in significant functional decline and requiring the use of a four-wheel walking frame. After extensive screening for pathological causes, the most significant findings were elevated C-reactive protein, erythrocyte sedimentation rate, and white cell count with a predominant neutrophilia. Numerous forms of imaging were undertaken, with fluorodeoxyglucose-positron emission tomography suggestive of vasculitis in medium and small vessels within the bilateral lower limbs. The patient was commenced on prednisolone and later methotrexate, with complete resolution of symptoms three and a half months later. Symptom resolution was compared with repeat fluorodeoxyglucose-positron emission tomography, which also demonstrated the resolution of lower limb vasculitis changes. In the absence of other identified precipitants, as well as with the patient having a continuously elevated multiplex polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 during admission, it outlines a unique situation of such an infection being a potential trigger for isolated vasculitis in medium to small vessels. As this is not well expressed in the literature, it provides a basis for further research, whilst also assisting in the work-up of other patients who may present similarly.