Langerhans cell histiocytosis mimicking preseptal cellulitis.

A 7-year-old girl presented with signs of preseptal cellulitis that initially responded to antibiotics but then relapsed. Computed tomography scan revealed a cystic lesion in the preseptal tissues with associated soft tissue swelling and lacrimal gland inflammation. Anterior orbitotomy revealed a hemorrhagic-appearing lesion extending from the preseptal tissues subperiosteally along the roof of the orbit. The lesion was excised and histopathology and immunohistochemical staining confirmed a diagnosis of Langerhans histiocytosis. Management of this condition depends on the extent of systemic involvement, with single bony lesions usually pursuing a benign course and often spontaneously regressing or resolving following biopsy. This case serves to highlight that an underlying cause for preseptal cellulitis should be sought and if there are relapses or inadequately resolving signs of preseptal cellulitis, then prompt investigation to rule out other causes is required.