The differential diagnosis between primary cutaneous large B-cell lymphoma and cutaneous follicular lymphoma: prognostic and therapeutic implications.

The differential diagnosis between primary cutaneous diffuse large B-cell lymphoma and cutaneous follicular lymphoma is one of the most difficult aspects of dermatopathology, even though morphological criteria are well established and a wide panel of antibodies is available to every laboratory. Such diagnosis is, however, not trivial because it has important prognostic and therapeutic implications. Nevertheless, when the literature is reviewed, there is a feeling that the diagnostic deficits from the past could perhaps be responsible for the differences observed in the therapeutic results with less aggressive treatments, such as rituximab. The current report briefly revises some cases of primary cutaneous diffuse large B-cell lymphoma treated with rituximab, which have been reported in the literature. It also presents an additional case emphasizing the current approach to the differential diagnosis.