CD30 positive atypical lymphocytes in perniosis: a potential histopathologic pitfall in a benign condition.

In classical clinical perniosis (chilblains), the presence of atypical lymphocytes with immunohistochemical staining positive for CD30 is unusual and rarely reported. Here we report 2 cases of clinical perniosis, one in a 16-year-old girl and another in a 67-year-old woman. The biopsies revealed lymphocytic infiltrates, papillary dermal edema, and atypical cells highlighted with a CD30 immunohistochemical stain. Our cases demonstrate the importance of clinicopathologic correlation in the assessment of CD30 positive lymphocytes in benign nonneoplastic conditions. Dermatopathologists must be aware of this potential histologic pattern in perniosis to prevent misdiagnosis and overtreatment of this condition.