Paracentrotus lividus is the most common variety of sea urchin in the west coasts of Spain and has commercial value for the alimentary industry. Puncture with the spine of its rigid external skeleton may cause mechanical injury by skin penetration. It causes immediate local symptoms and, in some cases, a delayed reaction occurs in the site of injury, weeks to months later. In this case, persistent, firm, flesh-colored papules or nodules develop.
Material and methods
Twenty-four biopsies from 21 patients with the diagnosis of sea urchin granuloma were studied, as well the clinical data. Specimens were routinely processed and stained with hematoxylin–eosin and leucocyte common antigen, CD20, CD3, CD4, CD8, CD30, CD68, kappa and lambda.
Patients presented with persistent, single or multiple, nodules or papules, usually located in the hands. They developed from 2 weeks to over 1 year after the injury. Histopathologically, granulomas were present in all but one case. Sarcoidal granulomas were more common than suppurative or necrobiotic granulomas. Immunohistochemistry showed a polymorphous lymphoid inflammatory infiltrate, with T leucocytes predominating in most cases.
Histopathological examination of sea urchin granulomas shows a non-specific granulomatous inflammation, in most cases of sarcoidal type. Being aware of the triggering event is necessary for the correct diagnosis.