Introduction: Langerhans Cell Histiocytosis (LCH) is a tumour-like condition that runs a variable clinical course. Recent series1,2 have suggested that skeletally immature patients with a solitary bony focus (eosinophilic granuloma) have an especially good prognosis.

Aim: To compare recurrence/progression rates for Scottish patients with solitary eosinophilic granulomas, according to skeletal maturity.

Methods: Retrospective case note review of patients identified from the Scottish Bone Tumour Registry.

Results: We identified 70 cases of biopsy-proven non-spinal eosinophilic granuloma of bone. Of these, 39 were skeletally immature (< 16 years) and 31 were skeletally mature (> 16 years). Follow-up (mean 8.25 years) was either continuing or to discharge/death. On the basis of initial screening (skeletal survey/bone scan), 9 cases (13 %; 4 and 5 patients, from the paediatric and adult groups respectively) were found to have multi-focal disease. Considering those with unifocal disease:

in the immature group, 6 patients (ex 35; 17%) developed a further manifestation of the condition (2 had recurrences at same site; 2 developed a distinct focus in bone; 1 developed a distinct soft tissue lesion causing spinal cord compression; 1 developed diabetes insipidus),

Conclusions: For this population, these data show that the prognosis for paediatric patients with isolated eosinophilic granuloma of bone must be more guarded than that suggested by other series1,2.