Cholestatic pruritus - the role of cutaneous mast cells and nerves.

BACKGROUND: The pathogenesis of pruritus in cholestatic liver disease is poorly understood. Cutaneous mast cells and nerves are thought to contribute to pruritus in several dermatological diseases. AIM: To determine if cutaneous mast cell density, neural density and mast cell-neural interaction are increased in patients with pruritus and cholestatic liver disease. METHODS: Skin biopsy specimens from (i). patients with pruritus due to cholestatic liver disease (CLDP+; n = 6), (ii). patients with chronic liver disease without pruritus (CLDP-; n = 5), and (iii). healthy controls (n = 6) were studied. Biopsies were dual stained immunohistochemically for mast cells and nerves. RESULTS: Mast cell density in the control group was not significantly different from that in CLDP+ group or from that in the CLDP- group. Similarly neural density was not significantly different between groups when assessed either in terms of total nerve area, or in terms of the number of neural elements seen. The frequency of mast cell-nerve contact was not significantly different between groups. CONCLUSIONS: These findings suggest that mast cells, nerves or interaction between the two may not contribute to cholestatic pruritus. Therefore, therapies targeted at cutaneous mast cells or nerves are unlikely to be of benefit.