Role of Fine Needle Aspiration in the Diagnosis of the Rare Disease of Langerhans Cell Histiocytosis in a Child

Langerhan’s cell histiocytosis (LCH) results from the proliferation of immunophenotypically and functionally immature, morphologically rounded Langerhan’s cells along with eosinophils, macrophages, lymphocytes, and, commonly, multinucleated giant cells. Here we report a case in a 6-year-old boy of differential diagnoses including dermatopathic lymphadenitis (DL), parasitic infection, Kimura’s disease, hypersensitivity reactions, cat-scratch disease, sinus histiocytosis with massive lymphadenopathy (SHML), hyperplasic lymph nodes, and lymphoma. 1. Introduction Controversy exists regarding whether the immunologic abnormalities observed in LCH are the cause of the clonal proliferation lesional Langerhan’s cells [1]. The etiology of LCH is unknown. Efforts to define a viral cause have not been successful [2, 3]. The incidence of LCH has been estimated to be 2 to 10 cases per million children aged 15 years or younger [4, 5]. The male to female ratio is close to one and the median age of presentation is 30 months. The nomenclature used for LCH indicates the disease extent (i.e., single organ, single system, multisystem, or diffuse). Prognosis and treatment are closely linked to the extent of disease at presentation and whether high-risk organs (spleen, liver, bone marrow, and lung) are involved. The outcome for children with LCH involving low-risk organs (skin, bones, lymph node, and pituitary gland) has always been excellent. 2. Case Report A 6-year-old boy presented with a four-week history of right neck swelling. On clinical examination a 3 × 2？cm right cervical enlarged lymph node was noted. The patient did not have any other lymphadenopathy. There was no significant clinical history including weight loss or fever. Skeletal survey was normal. There were no osseous lytic lesions. PET scan was reported to be normal. Fine needle aspiration (FNA) of the right neck lymph node was performed. Cytology smears were prepared. 3. Materials and Methods Diff-Quik (Medical Chemical Corp., Torrance, CA, USA) and Papanicolaou stains (Cardinal Health, Ontario, Canada) were performed. The residual pellet, after Cytospin processing, was fixed in 10% buffered neutral formalin for cell block preparation followed by hematoxylin and eosin (H&E) staining and ancillary studies. Immunocytochemistry stains were performed on unstained sections of formalin fixed, paraffin embedded cell block by the standard avidin-biotin technique. The panel of antibodies used included CD1a, CD68, and S 100. 4. Results The cellular aspirate smears showed numerous single lying mononucleated and