Pseudosquamous adenocarcinoma of the lung is an unusual morphologic variant of poorly differentiated non-small cell lung carcinoma that superficially resembles a squamous cell carcinoma. We have examined 10 cases of these tumors in 4 women and 6 men, aged 47 to 93 years. The tumors were all peripheral and measured from 1.5 to 5.5 cm. All cases were characterized by solid nests of large polygonal tumor cells containing atypical nuclei with abundant cytoplasm and sharp cell borders, adopting a pavement-like architecture that simulated squamous cell carcinoma. Some cases demonstrated intracytoplasmic hyaline inclusions suggestive of keratinization. The nests of tumor cells often showed central comedo-like areas of necrosis. Intercellular bridges were not seen in any of the cases. The tumors often displayed marked clearing of the cytoplasm enhancing their epidermoid appearance. In 4 cases, the solid pseudosquamous areas were seen to merge with a focal lepidic adenocarcinoma component, and in 1 case, abortive microscopic foci of acinar differentiation were also noted within the tumor. One case showed focal sarcomatoid spindle cell areas. The tumor cells were negative for p40 and CK5/6 and labeled with TTF1 or Napsin-A, confirming an adenocarcinoma phenotype. Clinical follow-up information was available in 8 patients; 6 patients died of their tumors between 6 months to 11 years after diagnosis (mean: 3.1 y). One patient died of complications related to surgery and one patient with a low-stage tumor died at 27 years from other causes. Solid pattern adenocarcinomas can be confused for squamous cell carcinoma and may require immunohistochemistry to determine their true phenotype.

中文翻译：

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肺假鳞状腺癌：10 例临床病理学和免疫组织化学研究。


肺假鳞状腺癌是低分化非小细胞肺癌的一种不寻常的形态变异，表面上类似于鳞状细胞癌。我们检查了 10 例此类肿瘤，其中包括 4 名女性和 6 名男性，年龄在 47 岁至 93 岁之间。肿瘤均为外周肿瘤，尺寸为 1.5 至 5.5 厘米。所有病例的特征都是大的多边形肿瘤细胞的实心巢，含有不典型的细胞核，细胞质丰富，细胞边界清晰，采用模拟鳞状细胞癌的路面结构。一些病例显示细胞质内透明包涵体提示角化。肿瘤细胞的巢通常显示中央粉刺样坏死区域。在所有病例中均未发现细胞间桥。肿瘤通常表现出明显的细胞质清除，增强其表皮样外观。在 4 例中，可见实性假鳞状区域与局灶性鳞状腺癌成分合并，在 1 例中，在肿瘤内还发现腺泡分化的流产微观病灶。 1例显示局灶性肉瘤样梭形细胞区。肿瘤细胞 p40 和 CK5/6 呈阴性，并用 TTF1 或 Napsin-A 标记，证实了腺癌表型。 8 名患者获得了临床随访信息； 6 名患者在诊断后 6 个月至 11 年内死于肿瘤（平均：3.1 年）。一名患者死于手术相关并发症，一名患有低期肿瘤的患者在 27 岁时因其他原因死亡。实性腺癌可能与鳞状细胞癌混淆，可能需要免疫组织化学来确定其真正的表型。