WHO Classification of Tumours 5th Edition Digestive System Tumours by WHO Classification of Tumours Editorial Board (z-lib.org).1

Oesophageal adenosquamous and
mucoepidermoid carcinomas
Brown IS
Ohashi K
Definition
Adenosquamous carcinoma of the oesophagus is an oesophageal
neoplasm composed of separate malignant squamous
and glandular components. Mucoepidermoid carcinoma of
the oesophagus is an oesophageal neoplasm composed of an
admixture of malignant epidermoid, intermediate, and mucous
cells.
ICD-0 coding
8560/3 Adenosquamous carcinoma
8430/3 Mucoepidermoid carcinoma
ICD-11 coding
2B70.Y & XH7873 Other specified malignant neoplasms of
oesophagus & Adenosquamous carcinoma
2B70.Y & XH1J36 Other specified malignant neoplasms of
oesophagus & Mucoepidermoid carcinoma
Related terminology
None
Subtype(s)
None
Localization
Adenosquamous carcinoma arises most commonly in the middle
oesophagus (582,2348), although a predominance of lower
oesophageal cases was observed in one recent series (3697).
Mucoepidermoid carcinoma occurs most commonly in the middle
and lower oesophagus (581).
Clinical features
The clinical features are similar to those of conventional adenocarcinoma
or squamous cell carcinoma of the oesophagus.
Epidemiology
These are rare tumours. Adenosquamous carcinoma presents
at a median patient age of 60 years and affects males 5 times
as often as females (582,2348). Mucoepidermoid carcinoma
accounts for < 1% of primary oesophageal carcinoma and
occurs most commonly in males, at a median patient age of
58 years (581).
to the pathogenesis of other adenosquamous carcinomas. It
has also been suggested that these tumours are simply primary
squamous cell carcinomas from which a subpopulation
has undergone diverging glandular differentiation (3764), or
primary adenocarcinomas showing squamous differentiation
(2500,1773,1777). There is also a rare possibility that the pattern
of adenosquamous carcinoma could be the result of a collision
of two separate primary carcinomas (one glandular and one
squamous). On balance, an origin from oesophageal submucosal
glands is favoured, supported by the common embryology
of oesophageal and salivary glands and the occasional
restriction of the tumour to the oesophageal submucosa, but
further evidence is needed. At other sites, notably the salivary
glands, mucoepidermoid carcinomas have defined molecular
characteristics that include translocations resulting in fusion
genes, which are not found in adenosquamous carcinomas
(852).
Macroscopic appearance
The macroscopic appearance is similar to that of squamous cell
carcinoma.
Histopathology
The histology of these lesions in their pure forms differs considerably,
but intermediate forms also appear to exist, and these
should probably be designated as adenosquamous carcinomas.
Pure mucoepidermoid carcinomas arising from submucosal
glands are extremely rare.
Adenosquamous carcinoma shows an admixture of distinct
components of both adenocarcinoma and squamous cell carcinoma.
Generally, the proportions of these components are
not relevant, although the Japanese Classification of Esophageal
Cancer (1428) requires > 20% of either component for the
diagnosis; otherwise the tumour is classified according to the
primary component alone. Any degree of differentiation can
Etiology
The risk factors are similar to those associated with conventional
squamous cell carcinoma.
Pathogenesis
Adenosquamous and mucoepidermoid carcinomas of the
oesophagus are of uncertain origin. The best evidence is for an
origin from a stem cell (581,1777), probably from the oesophageal
duct, giving rise to biphasic differentiation (3429), similar
Fig. 2.17 Oesophageal adenosquamous carcinoma. A characteristic admixture of
malignant squamoid cell and glandular components.
46 Tumours of the oesophagus
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