Tonic pupil is due to a lesion of orbital parasympathetic neurons in the ciliary ganglion or short ciliary nerves (1). Precise etiology of the condition remains obscure. In the case described here, development of “tonic pupil” was followed by systemic features typical of lymphomatoid granulomatosis, and diagnosis was confirmed by histology of the skin rash. This case underlines the heterogeneity of the causes of tonic pupil. Vascular occlusion can be a possible mechanism in the pathogenesis of tonic pupil.