関節リウマチ治療中の間質性肺炎悪化との鑑別が困難であった浸潤性粘液性腺癌

Invasive mucinous adenocarcinoma difficult to distinguish from worsening interstitial pneumonia during treatment for rheumatoid arthritis

間質性肺炎に癌の合併が多いことは広く認められている。

We report a case of invasive mucinous adenocarcinoma of a woman in her 50s. She was during treatment for rheumatoid arthritis and had interstitial pneumonia. The computed tomography（CT）scan revealed progressively increasing consolidation, raising concerns for exacerbating interstitial pneumonia. However, subsequent treatment for interstitial pneumonia proved ineffective. Consequently, transbronchial lung cryobiopsy was performed, leading to the diagnosis of invasive mucinous adenocarcinoma. When invasive mucinous adenocarcinoma arises concomitantly with interstitial pneumonia, distinguishing between the two conditions based on imaging studies can be particularly challenging. Even if the imaging history does not contradict a progression of interstitial pneumonia, it is imperative to consider invasive mucinous adenocarcinoma as a differential diagnosis.