Lymphomatous infiltration of the peripheral nervous system in enteropathy‐associated T‐cell lymphoma

Clinical record A 53-year-old woman with a 10-year history of coeliac disease controlled by a gluten-free diet presented with a 6-month history of dramatic weight loss and pyrexia. Physical examination showed wasting and peripheral oedema. Plasma albumin level was 23g/L (normal, 34-48 g/L). Computed tomography of head, neck, chest, abdomen and pelvis, gallium and positron emission tomography scans, liver biopsy and bone marrow biopsy were normal. The serum lactate dehydrogenase (LDH) level was 466 U/L (normal, 110-230 U/L), raising the possibility of occult malignancy, especially enteropathy-associated T-cell lymphoma (EATL). Endoscopic duodenal biopsy revealed mild increase in intraepithelial lymphocytes, crypt hyperplasia and villous abnormality in keeping with coeliac disease. Molecular clonality studies of the lymphoid cells in the duodenal biopsy yielded a monoclonal band of T-cell receptor (TCR) γ gene rearrangement in two separate series of biopsies taken 6 weeks apart. Refractory sprue was diagnosed, and the patient received sequential trials of prednisolone, cyclosporin A and infliximab without benefit. High dose cyclophosphamide (2 g/m 2 ) was administered 3 months later for presumed EATL. This resulted in immediate resolution of the fever and improved weight gain. The patient subsequently complained of paraesthesiae in her feet. Neurological examination was normal. Nerve conduction studies suggested an early axonal sensory peripheral neuropathy. Vitamin B 12 , folate, vitamin A-tocopherol, red blood cell transaminase and transketolase studies, vasculitic screen, glycated haemoglobin, syphilis serology and thyroid function tests were normal. Paraprotein was not detected in serum electrophoresis. Magnetic resonance imaging (MRI) of the brain showed non-specific patchy periventricular areas of high signal not suggestive of the suspected lymphoma. Her systemic symptoms of fever, sweats and weight loss responded to two further doses of cyclophosphamide (1 g/m 2 ), despite worsening neurological symptoms. After 3 months, the patient relapsed with recurrence of pyrexia, and the serum LDH level progressively rose to 838 U/L. Neuropathy progressed to the point where she could not walk. Reflexes were lost, with a glove-and-stocking pattern of sensorimotor disturbance. A repeated nerve conduction study confirmed severe axonal sensorimotor peripheral neuropathy affecting both upper and lower limbs. Cerebrospinal fluid was normal, and there were no malignant cells. Repeated investigations, including brain MRI and upper gastrointestinal endoscopy, did not reveal any further evidence of malignancy. A right sural nerve biopsy showed severe loss of myelinated nerve fibres, and many of the surviving fibres showed varying stages of axonal degeneration (Box 1) associated with a sparse, patchy endoneurial mononuclear cell infiltrate in some fascicles and prominent endoneurial fibrosis on trichrome stain. The CD45RB immunostain showed increased numbers of immunopositive endoneurial lymphoid cells that showed immunopositivity with the T-cell markers CD3 (Box 2) and CD5. The CD68 immunostain showed increased endoneurial macrophages, and ultrastructural assessment confirmed macrophage phagocytosis of degenerate myelinated fibres. CD20 immunostain was negative. The Congo red stain for amyloid was negative.