側頭筋浸潤を示す頭蓋Langerhans cell histiocytosisの1例

Langerhans Cell Histiocytosis of the Temporal Bones with Infiltration of Temporal Muscle: A Case Report

Ⅰ．はじめに

　Langerhans cell histiocytosis（LCH）は従来histiocytosis Xと総称された，小児に多く発症する好酸球性肉芽腫症（eosinophlic granuloma），Hand-Schüller-Christian病，Letterer-Siwe病を含む疾患群であり⁴⁾，免疫機構に関与するLangerhans cellと同様な形質をもつ異常組織球の単クローン増殖が病因とされている¹⁾．本疾患の病態は浸潤する臓器により多様であるが，全身型，局所型に大分され，骨に限局するものは現在も好酸球性肉芽腫症と呼ばれることが多く，頭蓋が好発部位の1つである．今回，9歳男児の頭頂骨に有痛性に急速増大し軟部組織浸潤を示したLCH外科治療症例を経験したため，画像診断上の特徴を含め考察する．

　A 9-year-old boy presented a painful right painful parietal mass that rapidly enlarged within a month. He had no other symptom of infection or malignancy. Laboratory findings were normal. Plain skull X ray demonstrated a "punched-out" lesion in the right parietal bone. Magnetic resonance (MR) imaging revealed a 4×4×3cm mass centered in the right parietal bone which was enhanced after administration of a contrast material. In addition, as well as the mass region, the pericranial soft tissue was densely enhanced. The parietal bone mass was soft and successfully removed. Histological examination disclosed Langerhans cell histiocytosis (LCH) infiltrating the temporal muscle. MR imaging is useful for diagnosis of LCH of the skull with soft tissue involvement.