FINE-NEEDLE ASPIRATION CYTOLOGY IN A CASE OF ISOLATED INVOLVEMENT OF THYROID WITH LANGERHANS CELL HISTIOCYTOSIS

We present an unusual case of isolated thyroid involvement with Langer hans cell histiocytosis (LCH), diagnosed presumptively by fine-needle aspiration (FNA) cytology and subsequently confirmed by immunohistoche mistry in a 13-year-old boy. The cytologic findings include high cellu larity in a hemorrhagic background, the presence of characteristic mon onucleated and multinucleated Langerhans cells with prominent nuclear grooves, and abundant foamy cytoplasm in a background of mixed eosinop hilic and lymphocytic infiltrate, along with the presence of few focal aggregates of benign thyroid follicular cells. Further diagnostic con firmation was obtained by positive S-100 protein immunohistochemistry of the Langerhans histiocytes on paraffin-embedded sections of open th yroid biopsy of the prominently enlarged left lobe. We present the com plete clinicopathologic features of this case, along with ultrasound, computerized axial tomographic, and technetium-99 scan findings. We al so discuss possible differential diagnostic consideration in light of a review of the literature and the role of FNA cytologic diagnosis in such a rare yet cytomorphologically characteristic case. (C) 1998 Wile y-Liss, Inc.