Lymphomatoid papulosis with associated cerebellar lesion of similar histology and T-cell clonality

Abstract

A 9-year old boy presented with a 4-month history of a truncal monomorphic eruption with self-healing papulonecrotic lesions. A skin biopsy revealed a dermal infiltrate of CD4, CD8 and CD30-positive T-cells, consistent with lymphomatoid papulosis. He responded to 4 months of treatment with narrowband UVB phototherapy (311 nm) which stabilised his disease. Five years later he presented with an acute onset of nausea and vomiting, dizziness, headache and ataxia. Magnetic resonance imaging of the brain revealed a lesion in the cerebellum and stereotactic resection was undertaken. Histology showed CD4, CD8 and CD30-positive T-cells similar to his skin lesions, with a monoclonal T-cell receptor (TCR) gamma gene rearrangement. Subsequent analysis of the skin detected a monoclonal band of the same size as the cerebellar lesion. Treatment was initiated for a primary central nervous system (CNS) lymphoma but ceased after one course of high-dose methotrexate. Opinion on the pathology was divided as to whether the cerebellar lesion represented an atypical reactive T-cell lymphoproliferative response or a T-cell lymphoma. On follow-up 2 years later, the patient remains clinically and radiologically clear, making CNS lymphoma unlikely.