True histiocytic lymphoma as a second neoplasm in a follicular centroblastic-centrocytic lymphoma.

We report on a patient who developed a true histiocytic lymphoma, 16 years after initial diagnosis of a follicular low grade centroblastic-centrocytic lymphoma with several recurrences. We consider, out of gene rearrangement and immunohistochemical studies, that in this case, true histiocytic lymphoma is a second neoplasm in the evolutive course of the low grade lymphoma. The natural history of a low grade malignant lymphoma is to develop into a high grade large cell lymphoma and, if a second neoplasm appears, it is usually an epithelial tumor. This fact makes our report unique, as it would be, to our knowledge, the first case of true histiocytic lymphoma as the second neoplasm of another lymphoma.