Primary cutaneous ganglioneuroma arising within a seborrheic keratosis: a rare association

A 75-year-old woman presented to her general practitioner with a keratotic skin lesion on her abdomen. Microscopic examination showed an irritated seborrheic keratosis. However, further inspection revealed a well-defined dome-shaped area in the dermis showing a number of small nerve fibres admixed with relatively few mature ganglion cells. Both the spindle cell component and the ganglion cells stained positively for S-100 protein, neurofilament protein and CD56 (Leu-19, NCAM) by routine immunohistochemistry. Primary cutaneous ganglioneuroma is an exceedingly rare benign tumour of the skin with only 13 cases having been reported in English literature. We describe the second case of primary cutaneous ganglioneuroma associated with seborrheic keratosis.