An uncommon diagnosis for a recurrent erythematous patch in a paediatric patient.

A 14-year-old girl presented with a circular erythematous patch over the left buttock for approximately 10 years, with ongoing ulceration and papules developing over the last 4 years. Punch biopsies were taken within and above the patch for diagnosis. Both revealed marked inflammatory infiltrates with atypical, irregular lymphocytes and increased mitosis. Immunostaining revealed CD8 positivity and a pan T helper cell phenotype. T cell receptor gene rearrangement analysis showed T cell clonality in both biopsies. These findings were consistent with mycosisfungoides and associated lymphomatoid papulosis. Both are rare conditions but have been associated in 5%-20% of cases. A definitive association has not yet been established; however, T cell monoclonality shows 50%-60% share a common origin. Management options are extensive with no one treatment showing superiority. Our patient received low-dose radiotherapy with good outcomes, but subsequently required further radiotherapy.

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

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.

Regional lymphomatoid papulosis in a child--treatment with a UVB phototherapy handpiece.

Lymphomatoid papulosis (LyP) is a rare skin lymphoproliferative disorder that has been reported only rarely in children. It is included in the World Health Organization classification of cutaneous lymphomas. We report a case of LyP in a 13-year-old Caucasian girl who presented with a 6-month history of recurrent papular lesions on the left upper arm. Histopathologic examination showed a diffuse cellular infiltration of small and medium-sized T lymphocytes CD30+ in the superficial dermis. Treatment was started using a UVB phototherapy handpiece (twice weekly), with resolution of the lesions after 6 weeks of treatment. There was a relapse after 9 months with a good response after six more sessions of treatment. The patient is in good health without lesions after 12 months of follow-up.