Recurrent Langerhans cell histiocytosis at the site of prior craniotomy: case report.

Tumors of the CNS represent the largest group of solid tumors found in the pediatric patient population. Langerhans cell histiocytosis (LCH) is an inflammatory lesion that may present in bone and/or soft tissue, including the CNS. Management depends on the extent of multisystem involvement, which determines resection with or without systemic chemotherapy. The authors report on the case of a child who underwent an open craniotomy for biopsy of a pituitary stalk lesion followed by neuropathological assessment, procedures used to diagnose LCH. The patient then underwent 12 months of systemic chemotherapy with subsequent resolution of the pituitary stalk lesion. Two years following pathological diagnosis, the patient presented with frontal orbital pain at the site of the prior craniotomy. Advanced imaging revealed MRI enhancement and radiotracer uptake of a soft-tissue growth at the frontal burr-hole site and MRI enhancement at a posterior burr-hole site without soft-tissue growth. The patient then underwent open biopsy and curettage that revealed LCH recurrence at the site of prior craniotomy. This case demonstrates that LCH may represent an abnormal reactive clonal proliferation of dendritic cells, rather than a de novo malignant neoplasm that can occur at sites of prior craniotomy despite systemic chemotherapy. The authors advocate close follow-up with contrast-enhanced imaging. Special attention should be given to sites of prior surgical manipulation to avoid missing distant sites of recurrence.