Basaloid-squamous carcinoma of the upper aerodigestive tract and so-called adenoid cystic carcinoma of the oesophagus: the same tumour type?

Basaloid-squamous carcinoma of the larynx, pharynx and base of tongue and the so-called adenoid cystic carcinoma of the oesophagus are rare but distinctive tumours associated with a grave prognosis. They occur most commonly in elderly males and present at an advanced stage. Our study of four such laryngeal tumours and five such oesophageal tumours shows that they are histologically and immunohistochemically identical, providing support for the idea that they are the same tumour type. They show a biphasic pattern in which basaloid tumour is intimately associated with a neoplastic squamous component which can be invasive or in situ. The basaloid component is in the form of invasive lobules with frequent comedo-necrosis and hyalinization. The constituent cells possess pale pleomorphic nuclei with frequent mitoses. Immunoreactivity for cytokeratin in the basaloid component is remarkable for its absence or weak and focal nature. Review of the literature shows that only a few cases of 'adenoid cystic carcinoma' of the oesophagus are bona fide examples of adenoid cystic carcinoma as it occurs in the salivary glands, while the others are identical to basaloid-squamous carcinoma of the upper aerodigestive tract. Their distinction is important because genuine adenoid cystic carcinoma is much less aggressive than basaloid-squamous carcinoma.