This first case contains undulating epithelial structures lined by squamous and mucin containing cells, which may not be appreciated fully at this power
Other structures consist of dilated cystic spaces lined by malignant squamous cells with comedonecrosis in the lumen.
This area is composed of malignant squamous epithelium and surrounded by inflamed desmoplastic stroma.
This area may appear similar but has some more luminal cells which are mucinous. These cells are intimately admixed with the squamous ones. .
Squamous proliferation growing in broad irregular nests. The stroma in between is desmoplastic.
Again, you can appreciate the mucin within some of the neoplastic glandular cells.
Mucicarmine can be helpful in highlighting the adenocarcinomatous component.
Keratin 5/6 can highlight the squamous component. The mucinous cells are negative.
This different case has a more glandular and mucinous look.
In fact, the glandular cells focally assume a signet ring morphology.
Some areas demonstrate well-differentiated glands with luminal mucin and basally situated nuclei.
Squamous areas, by definition, are also well-presented and comprised over 10% of the tumor. This is an area of the bronchus with an in situ lesion and an underlying invasive component.
Adenosquamous carcinoma of the lung demonstrate features of both adenocarcinoma and squamous cell carcinoma. The two components can be intimately admixed or sharply demarcated (although this is rare). Each component should comprise at least 10% of the tumor.
There is some literature suggesting that this histologic subtype is more aggressive than either the "pure" forms of adenocarcinoma or squamous cell carcinoma. For example, in one study, 3 and 5 year survival for stage I adenosquamous carcinoma was similar to adenocarcinoma or squuamous cell carcinoma presenting at stage IIIA (Nakagawa). Other studies fail to show any significant difference (Nakagawa).
Nakagawa K, et al. Poor prognosis after lung resection for patients with adenosquamous carcinoma of the lung. Ann Thorac Surg. 2003 Jun;75(6):1740-4.