Hydroa-like lymphoma with CD56 expression.

Hydroa-like lymphoma is an extremely rare and aggressive lymphoma described in children from Latin American countries (Mexico, Guatemala and Peru) and Asia (Japan, Korea and Taiwan). Clinically, patients present with vesicles, ulcers and scars occurring on both sun-exposed and non-sun-exposed areas. In contrast to classical hydroa vacciniforme, hydroa-like lymphoma is associated with systemic lymphoma of T-cell type that expresses either CD4 or CD8. We report the findings from two unusual cases of hydroa-like lymphoma that, unlike the cases described thus far in the literature, express CD56 and resemble natural killer cell lymphomas. Two 9-year-old boys presented with clinical histories of waxing and waning ulcerative blistering lesions since 3 years of age. Histological examination of skin biopsies from both cases showed periappendigeal infiltrates of atypical lymphocytes. Immunohistochemical studies showed that the cells were highlighted by markers for CD3, CD56 and CD30, but did not express CD4 and CD8. Both patients were alive with disease 1 year later. Hydroa-like lymphoma with natural killer-cell phenotype may have a similar outcome to T-cell derived hydroa-like lymphoma, but the prognosis appears to be better than classic NK lymphomas, which in general behave in an aggressive fashion.