The development of peripheral T-cell lymphoma after successful treatment for diffuse large B-cell lymphoma in a patient with suspected adult onset immunodeficiency: more questions than answers?

We present the case of a 60-year-old woman who developed peripheral T-cell lymphoma following successful treatment for high-grade B-cell non-Hodgkin's lymphoma. We consider the possible aetiology of this unusual occurrence. We hypothesise that this case represents one of the undiagnosed adult-onset immunodeficiency, in which the pathogenesis of the patient's T-cell lymphoma may have been in part iatrogenic, namely related to previous immunotherapy with rituximab. We feel this case highlights the importance of rebiopsy in patients with recurrent lymphadenopathy and a history of haematological malignancy and hence acts as an important aide memoir in the investigation of such cases.