Mycosis Fungoides : Transformation

Comments:
Mycosis Fungoides (MF) - Transformation: MF pursues a fairly indolent clinical course except when it undergoes transformation to a large T-cell lymphoma - defined as 25% or more of the lymphocytic infiltrate composed of large cells on biopsy of an MF lesion.

It occurs in 10-23% of cases and is usually seen in the tumor stage but can sometimes occur in patch or plaque stages. Median time from the diagnosis of MF to transformation is about 6.5 years. Extracutaneous spread is seen in 40-50% of cases.

The prognosis is extremely poor with a median survival time of 1-3 years once large cell transformation has occurred. This low power view of large cell transformation in MF shows dense dermal infiltrate.

Reference:
Vergier B et al. Transformation of mycosis fungoides: clinicopathological and prognostic features of 45 cases. French Study Group of Cutaneous Lymphomas. Blood. 2000 Apr 1;95(7):2212-8.