Langerhans cell histiocytosis in lymph nodes - cytomorphological diagnosis and pitfalls

Abstract

Background Langerhans cell histiocytosis (LCH) is a rare disorder of unknown aetiology that may present as a multisystem or unisystem disease. The Lymph nodes can be involved as part of disseminated disease, as a metastatic site draining a focus of LCH or may be a unisystem involvement. Paucity of literature on the cytomorphology of LCH in lymph nodes led us to undertake this study. Materials and methods Nine cases with a confirmed histological diagnosis of LCH and a prior lymph node aspirate were retrieved over a 12 year period (1988–1999). Five more cases were reviewed where the cytological diagnosis of LCH was rendered on a background of clinical and radiological findings. Papanicolaou and May Grunwald–Giemsa-stained smears were examined. S-100 protein staining was available in four cases. Results and conclusions Nine cases had multisystem involvement, while in five cases only lymph nodes were involved. There were eleven males and three females; age ranged from five months to 27 years. The cytological diagnosis of LCH had been rendered in six, suspected in four and missed in four. Of the latter, two were reclassified as LCH on review, one as reactive lymphadenitis and in one a necrotising lesion was suspected. The pathognomonic ‘LCH cell’ was identified in 12 of 14 cases along with varying numbers of eosinophils, polymorphs and lymphocytes. Giant cells were seen in only six cases. In conclusion lymph node involvement by LCH can be identified on aspirates. However, LCH must be differentiated from dermatopathic lymphadenitis, sinus histiocytosis with massive lymphadenopathy and Hodgkin's disease.