Unifocal bony lesion of langerhans cell histiocytosis of tibia in a child mimicking osteomyelitis : A diagnostic challenge.

ABSTRACT

Langerhans cell histiocytosis (LCH) is a rare proliferative histiocytic disorder of unknown etiopathogenesis. The clinical presentations range from unifocal or multifocal bony lesions to disseminated form of the disease with multiorgan involvement. The unifocal bony lesion (Solitary eosinophilic granuloma) carries a good prognosis. We report such a case of unifocal bony lesion of LCH involving tibia in a 8 years old female child. The clinical and radiological manifestations were non specific, enlightening the suspicion of osteomyelitis. A curettage excision biopsy was performed which on microscopy revealed sheets of eosinophils in milieu of Langerhans cells, giant cells, lymphocytes and plasma cells. Langerhans cells showed strong immunoreactivity for S-100 and CD1a antigen thus establishing the diagnosis of LCH. LCH of long bones may be a rare entity but it must be kept in mind as a differential diagnosis whenever a child presents with features of osteomyelitis.