Neural spectrum: palisaded encapsulated neuroma and verocay body poor dermal schwannoma

We examined 25 palisaded encapsulated neuromas (PEN) of the skin and used p eripherin antibody as an immunohistochemical label for axons. Quantitative analysis of the axon to schwann cell nuclear ratio for each PEN was determi ned by examining cross-sectioned neuroid fascicles. This revealed that 120 of the 253 cross-sectioned fascicles in PEN lacked axon and only 5% of the fascicles had an axon to schwann cell nuclear ratio greater than 1 : 2. In contrast, all fascicles in 40 dermal nerves adjacent to PENs as well as 35 traumatic neuromas in surgical scars had an axon to schwann cell nuclear ra tio of at least 1 : 2 and the majority a ratio of 1 : 1 or higher. These re sults suggest that there is a spectrum between PENs which are axon rich to a form of schwannoma with an identical histopathology which lacks significa nt axonal content and that not all PENs are true neuromas.