FDG‐PET guided diagnosis of vaginal intravascular diffuse large B‐cell lymphoma

A 76-year-old woman presented with a 6-month history of progressive bilateral lower limb weakness, anorexia and weight loss and the recent onset of urinary and faecal incontinence with saddle anaesthesia. There was no palpable lymphadenopathy. Urgent magnetic resonance imaging (MRI) ruled out spinal cord or cauda equina compressive lesions. Blood tests showed a raised lactate dehydrogenase (LDH) and erythrocyte sedimentation rate with an IgM paraprotein of 7 g/l; immunoglobulins were otherwise normal. Cerebrospinal fluid analysis showed a reactive lymphocytosis on morphology and by flow cytometry. Bilateral bone marrow aspirates and trephine biopsies were normal. Computed tomography (CT) was entirely normal but a repeat MRI with gadolinium showed enhancement of lumbosacral nerve roots suggestive of infiltrative disease. [F]fluorodeoxyglucose (FDG) positron emission tomography (PET) showed diffuse uptake in the uterus, cervix, vagina and numerous groups of lymph nodes throughout the body. The FDG-PET findings led to a vaginal mucosal biopsy, which showed subepithelial capillaries packed with neoplastic lymphoid cells (left) expressing CD20 (right), CD79a and CD5 with a Ki-67 index of 100%; the histological features were those of intravascular diffuse large B-cell lymphoma (DLBCL). At the time of diagnosis the patient had a performance score of 4 and she remained an inpatient. She received twice weekly intrathecal methotrexate, followed by one cycle of CVP (cyclophosphamide, vincristine and prednisolone combination chemotherapy). Rituximab was given 1 week later due to the high risk of tumour lysis syndrome, which has been reported previously. Unfortunately she developed neutropenic sepsis and died 2 weeks after diagnosis. Despite extensive prior investigations it was the results of the FDG-PET scan that eventually guided the biopsy site. The lack of solid lesions makes routine CT and MRI unhelpful in diagnosing this rare subtype of extranodal DLBCL; approximately 50% of patients are diagnosed at autopsy. This case highlights how the nonspecific and diverse symptoms, in the absence of significant lymphadenopathy, can result in critical delays in diagnosing this clinically aggressive lymphoma and how the use of FDG-PET scanning in such patients can guide the biopsy site.