Early stage mycosis fungoides with focal CD30-positive large cell transformation

Mycosis fungoides (MF) is typically an indolent disease except when large cell transformation (LCT) occurs. The incidence of LCT has been reported to range from 6% to 23% under the criterion of the presence of more than 25% of large cells in a biopsy of typical MF lesions. LCT is more common in advanced-stage MF, but very rarely found in its early stage. Herein, we present a 45-year-old woman with patch stage MF (Stage IB) who developed a papule within one patch, which revealed large cell transformation with expression of CD30 immunostaining on histopathology. The patient then received phototherapy with narrow-band UVB. The skin lesions regressed quickly and no new skin lesions had been noted during the 6-month follow-up. Intense monitoring for recurrence and extracutaneous involvement is still recommended. In this article, we also review the published articles of mycosis fungoides with CD 30-positive large cell transformation and analyze the clinicopathological and prognostic features.