Persistent atypical lymphocytic hyperplasia following tick bite in a child: report of a case and review of the literature.

We report a 6-year-old girl who developed a red papule on the posterior neck at the site of a previous tick bite. Initial biopsy was performed a year after the bite and the specimen showed a dense lymphoid infiltrate with admixed CD30+ cells. The patient was referred to our center because of concern about the development of a CD30+ lymphoproliferative disorder. The lesion was completely excised. Histology showed no evidence of a clonal lymphoproliferative disorder or Borrelia infection, but persistence of CD30+ cells. This case demonstrates that a tick bite reaction can persist for more than 1 year and show immunophenotypic and morphologic overlap with a CD30+ lymphoproliferative disorder. Complete history with thorough clinical and histopathologic evaluation is necessary to arrive at the correct diagnosis.