Use of bevacizumab in a patient with Whipple's disease: managing diagnostic uncertainty.

A man in his 30s with intellectual disability presented with 1 month of diarrhoea, weight loss and dyspnoea. Investigations were hampered due to significant anxiety. Laboratory tests detected microcytic anaemia and hypoalbuminaemia. CT demonstrated a fat-containing infiltrate in the mediastinum, mesentery and axillae, and pulmonary ground-glass infiltrates. Biopsy of the axilla showed cystic lymphatic malformations involving adipose tissue and lymph nodes, leading to a provisional diagnosis of generalised lymphatic anomaly. Over the subsequent 4 months, the patient's respiratory status deteriorated, leading to type 1 respiratory failure necessitating intubation. After multidisciplinary discussion, a decision was made to trial bevacizumab, an anti-VEGF agent, with subsequent improvement in respiratory status. While intubated, gastroscopy was performed; duodenal biopsies revealed pathognomonic changes of Whipple's disease, confirmed on PCR of duodenal and axillae biopsies. This was deemed the most likely unifying diagnosis; antibiotic treatment was commenced, bevacizumab was ceased, and the patient has remained well after 18 months.