Krause's end-bulb microtumor of the conjunctiva: optic and ultrastructural description of a case.

Ultrastructural examination of a conjunctival biopsy of a 90-year-old woman with a history of chronic lymphatic leukemia showed numerous densely packed structures located below the epithelial conjunctival layer. They were composed of concentrical flattened lamellae arranged around one or several clear cores containing a large number of mitochondria. The plasma membranes of the lamellae displayed large numbers of pinocytotic vesicles and resembled perineurial cell processes. The central areas were thought to be axons. Because of their conjunctional location and morphological features. The structures were categorized as nerve endings of the Krause's end-bulb type. The aberrant and profuse growth of these structures led to the diagnosis of Krause's end-bulb microtumor of the conjunctiva. We compare our findings with mucosal neuromas, paraneoplastic lesions and age-related alterations are discussed, although they differ morphologically from Krause's end-bulb microtumor.