小野 倫子, 谷口 信行, 鯉渕 晴美, 藤井 康友, 尾本 きよか, 中村 みちる, 伊東 紘一

Tomoko ONO, Nobuyuki TANIGUCHI, Harumi KOIBUCHI, Yasutomo FUJII, Kiyoka ONOMOTO, Michiru NAKAMURA, Kouichi ITOH

自治医科大学臨床検査医学

Department of Clinical Laboratory Medicine, Jichi Medical School

キーワード : abscess, nocardiosis, soft tissue, ultrasound

ノカルジア症は放線菌属による日和見感染症であり, 最近AIDSや臓器移植後の患者で増加してきている. 肺への感染が最も多いが, 血行性に播種が起こると脳や軟部組織にも膿瘍を形成する. 今回我々は, 軟部組織内に多発性の膿瘍を形成した2症例を経験したので, その超音波像について報告する. 症例1は39歳, 女性. Subcutaneous panniculitic T-cell lymphomaのためプレドニゾロン30 mg/日, シクロスポリン200 mg/日を服用していた. 胸部X線異常陰影と背部及び下肢の腫瘤が出現し, 背部腫瘤の穿刺液と喀痰及び血液培養からノカルジアが分離された. 超音波検査では, 広背筋に境界明瞭で内部均一, 一部に無エコー域を伴う低エコー腫瘤を認めた. カラードプラ法では周辺及び内部に血流を認めなかった. 症例2は67歳, 男性. 類天疱瘡にてプレドニゾロン50 mg/日の内服とdouble filtration plasmapheresis療法を併用していた. 右上腕や項部及び臀部に多発性の腫瘤が出現し, 臀部腫瘤の生検にてノカルジア膿瘍と診断された. 超音波検査では, 右上腕皮下に比較的境界明瞭で内部に無エコー域を伴う低エコー腫瘤を, 項部に境界やや不明瞭で不整形の低エコー腫瘤を認めた. ノカルジア膿瘍の超音波像は, 一般的な膿瘍の所見とは異なっていることがあるため, 診断において注意が必要と考えられた.

Nocardiosis is an opportunistic infection caused by bacteria of the Actinomycetaceae family. The incidence of nocardial infections is increasing with the growing number of transplant and HIV-positive patients. Lung involvement is frequent, which causes soft-tissue and cerebral involvement by hematogeneous dissemination. We emphasize ultrasonographic findings in describing two cases of abscesses in soft tissue. Case 1: A woman aged 39 years had received daily doses of predonisolone (30 mg) and cyclosporin (200 mg) for subcutaneous panniculitic T-cell lymphoma. Some nodules on her back and lower extremities developed without inflammatory signs. Chest X-ray showed an abnormal shadow. Nocardia farcinica was isolated from aspiration material of the mass on her back, sputum and blood. Ultrasonograms showed a smoothly outlined hypoechoic mass in the latissimus dorsi muscle. The internal echo pattern was homogeneous and contained amorphous anechoic areas. Color Doppler ultrasonography detected no blood-flow signal in the mass. Case 2: A man aged 67 years had been treated with daily administration of predonisolone (50 mg) and double filtration plasmapheresis for bullous pemphigoid. Multiple nodules on his right upper arm, nuchal region, back, and left buttock were diagnosed as nocardial abscesses on biopsy of the mass on the buttock. The ultrasonogram showed a smoothly outlined hypoechoic mass with a central anechoic area in the subcutaneous layer of the right arm, and an irregularly outlined hypoehoic mass with heterogeneous internal echo texture in the nuchal region. Because ultrasonographic images of nocardial abscesses in soft tissue often appear atypical as abscesses, these findings should be borne in mind when diagnosing these lesions.