野竹 文章¹, 樋口 清孝², 林 光弘³, 芹澤 博美⁴

Fumiaki NOTAKE¹, Kiyotaka HIGUCHI², Mitsuhiro HAYASHI³, Hiromi SERIZAWA⁴

¹東京医科大学八王子医療センター放射線部, ²国際医療福祉大学大学院医療福祉学研究科, ³東京医科大学八王子医療センター乳腺科, ⁴東京医科大学八王子医療センター病理診断科

¹Department of Radiology, Tokyo Medical University Hachioji Medical Center, ²International University of Health and Welfare Graduate School of Medical and Welfare Studies, ³Department of Breast Oncology, Tokyo Medical University Hachioji Medical Center, ⁴Department of Pathology, Tokyo Medical University Hachioji Medical Center

キーワード : breast ultrasound, ductal carcinoma in situ, elastography, cancer cell density, histopathological images

目的：非浸潤性乳管癌（ductal carcinoma in situ: DCIS）はエラストグラフィで低いスコアを示すことが多い．その要因について病理組織像を定量的に検討した．対象と方法：2012年1月から2013年8月の間に手術でDCIS と確定診断され，エラストグラフィでItohらによるスコアに分類した18例を対象とした．病理組織像から腫瘍の癌細胞密度，管腔密度を算出しスコアとの相関を検討した．スコア（1‐3）を低スコア群，（4‐5）を高スコア群とし癌細胞密度の差を検討した．腫瘤と非腫瘤性病変に分類し癌細胞密度の差を検討した．結果と考察：スコア2は9例と一番多かった．スコアと癌細胞密度には正の相関を認めたが，スコアと管腔密度には相関は認めなかった．低スコア群は13例で高スコア群とくらべ多数であった．癌細胞密度は，低スコア群の方が低く両者の間に有意な差を認め， 非腫瘤性病変は11例と腫瘤とくらべ多数であった．そして，組織亜型分類ではコメド型が4例，乳頭型が3例，低乳頭型が2例，充実型が2例であった．癌細胞密度は，非腫瘤性病変の方が低く両者の間に有意な差を認めた．DCISは癌細胞密度の低い症例が多く，癌細胞密度が低いと低いスコアを示すことがわかった．結論：癌細胞密度の差はDCISがエラストグラフィで低いスコアを示す要因の一つであると推察できた．

Purpose: To quantitatively analyze ultrasound elastographic findings and histopathological images of patients with ductal carcinoma in situ (DCIS) and determine the predictors of a low elastography score. Subjects and Methods: Eighteen patients with a confirmed diagnosis of DCIS after surgery performed between January 2012 and August 2013 were included. We calculated cancer cell density and lumen density from histopathological images and examined their association with elastography scores. Patients were classified into low and high score groups according to an elastography score of 1 to 3 and 4 to 5, respectively, and into mass and non-mass abnormality groups according to lesion type. Differences in cancer cell density were determined between groups. Results and Discussion: The most common score was 2, which was seen in nine patients. The elastography scores were positively correlated only with cancer cell density. The low score group had a larger number of patients (n=13) and a significantly lower cancer cell density compared with the high score group, while the non-mass abnormality group had a larger number of patients (n=11) and a significantly lower cancer cell density compared with the mass group. In addition, the pathohistological subtype of non-mass abnormalities was comedo type in four patients, papillary type in three patients, low papillary type in two patients, and solid type in two patients. Conclusion: A low cancer cell density may be a predictor of a low elastography score in DCIS patients.