[Primary cutaneous monomelic B-cell lymphoma]

Cutaneous B cell lymphomas, especially when appearing as a monomelic papulonodular eruption, are rare.

Ms H. 87-year-old, consulted for a papulonodular eruption of the left lower limb which developed during the past 5 months. This limb had been the site of a lymphedema since a traumatism 8 years ago. Histopathological analysis and immunostaining of a nodule showed that it was a large cell lymphoma of follicular stem cells. There was no extracutaneous involvement and the patient was successfully treated with radiotherapy. Two months after the completed radiotherapy a cutaneous relapse on the trunk and the upper limbs was treated with cyclophosphamide-vincristine-prednisone chemotherapy.

Lymphedema probably played a role in the genesis of this lymphoma presumably by reducing the local immune response. It may have harmed endothelial cells and maintained an antigenic stimulation leading first to lymphocyte hyperplasia and eventually to a true lymphoma, in the same way this has been proved for some MALT lymphomas.