A 20 year old boy presents with an intermittent low grade fever, anorexia, and night sweats for 3 months. He also lost 8 kg of weight during the same period.

He also complains of feeling multiple 'lumps' in the left side of his neck for several weeks. Further questioning reveals that these have slowly enlarged over time.

There is no history of recent travel, exposure to infections, or animal or insect bites. He was in good health before the onset of symptoms, with unremarkable medical, surgical, and family histories.

He does not smoke or drink, and aside from trying out marijuana a couple of times several years ago, has never used recreational drugs. He is in a heterosexual relationship with a single regular partner.

A complete blood count is within normal parameters, as are renal and liver profiles. However, his ESR is 100 mm/1h.