Leber believes that there is a connection between phlyctenular inflammations and scrofula, although it cannot be strictly proven. The accompanying vesicular eruption on the skin is probably due to a multiple ectogenous infection of the cutis, while phlyctenulae in all probability do not arise in this way.
Reference: Leber T. On phlyctenular inflammation of the eye. Arch Ophthalmol. 1902;31:39.
A look at the past . . .. Arch Ophthalmol. 2003;121(8):1208. doi:10.1001/archopht.121.8.1208-a