We present a case of lung carcinoma with a unique biphasic feature. The patient was a 67-year-old male smoker with idiopathic pulmonary fibrosis (IPF). A subpleural tumor in the left lower lobe, embedded in fibrotic tissue, was resected. Histologically, the tumor consisted of major and minor components of mucoepidermoid carcinoma (MEC) and surrounding conventional lepidic adenocarcinoma, respectively. Both components had the same TP53 somatic mutation (p.V157F) but not Mastermind-like 2 (MAML2) gene rearrangement. The two components may have developed from an identical origin. The tumor could be trans-differentiating from lepidic adenocarcinoma to MEC, possibly promoted by IPF-induced tissue damage. The final diagnosis was “adenosquamous carcinoma with mucoepidermoid-like features (that may originate from lepidic adenocarcinoma).” This case has implications for the potential histogenesis of peripheral lung MEC. Over time, the MEC would expand and outgrow the lepidic adenocarcinoma, making it impossible to distinguish between fake and true MEC. The present case suggests that peripheral MEC could differ from proximal MEC in its histogenesis and molecular genetics. Thus, careful examination is necessary to diagnose peripheral lung MEC, particularly in patients with interstitial lung diseases.

中文翻译：

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具有独特双相特征的肺癌病例：对周围肺中发生的“假粘液表皮样癌”的组织发生的影响

我们提出了一个具有独特双相特征的肺癌病例。患者是一名 67 岁男性吸烟者，患有特发性肺纤维化（IPF）。切除了左下叶的胸膜下肿瘤，包埋在纤维化组织中。组织学上，肿瘤分别由粘液表皮样癌（MEC）和周围传统鳞状腺癌的主要成分和次要成分组成。两种成分均具有相同的TP53体细胞突变 (p.V157F)，但不具有类似 Mastermind 2 (MAML2) 基因重排。这两个组件可能是从相同的起源发展而来的。该肿瘤可能从鳞状腺癌转分化为 MEC，这可能是由 IPF 诱导的组织损伤促进的。最终的诊断是“具有粘液表皮样特征的腺鳞癌（可能源自鳞状腺癌）”。该病例对于周围肺 MEC 的潜在组织发生具有重要意义。随着时间的推移，MEC 会扩大并超过鳞状腺癌，从而无法区分假 MEC 和真 MEC。本病例表明，外周 MEC 在组织发生和分子遗传学方面可能与近端 MEC 不同。因此，需要仔细检查来诊断周围肺 MEC，特别是对于患有间质性肺疾病的患者。