13
Respiratory Tract
Fig. 13.69 Large-cell carcinoma. Pulmonary resection (H&E x MP).
Fig. 13.70 Giant cell carcinoma. Pulmonary resection (H&E x MP).
Giant cell carcinoma (Fig. 13.70), which has recently been
reclassified by the World Health Organization as a type of sar-
comatoid carcinoma,299 is characterized by the presence of pleo-
morphic multinucleated giant tumor cells. Neutrophils are often
observed within the cytoplasm of these cells. A similar histologic
appearance may result when neoplasms of other types are treated
by radiation. Giant cell carcinomas arising in the pancreas, liver,
thyroid, and other organs may metastasize to the lung. The
prognosis for patients with giant cell carcinoma is extremely
poor. Lipford and associates have suggested that the presence of
tumor giant cells in limited stage lung cancer is predictive of an
unfavorable outcome, regardless of the differentiation of the rest
of the tumor, although this observation has not been confirmed
by others.339,340 Adenosquamous carcinomas contain, by defini-
tion, significant areas of both glandular and squamous differen-
tiation.299 Although in several studies they comprise fewer than
5% of lung carcinomas,341-343 they are diagnosed with greater
frequency when tumors are extensively sampled.152 Adenosq-
uamous carcinomas tend to occur more peripherally than do
squamous cell carcinomas,342 and their behavior is reportedly
similar to that of adenocarcinomas.344 If ultrastructural criteria
Fig. 13.71 Small-cell carcinoma. Note nuclear molding, fine chromatin
pattern, high nuclear/cytoplasmic ratios, and focal crush artifact. Bronchial
biopsy (H&E x MP).
are used, many squamous cell carcinomas, adenocarcinomas,
and large-cell undifferentiated carcinomas contain evidence of
both squamous and glandular differentiation.345
Small-cell carcinoma of the lung is now subdivided into only
two types in the current WHO classification: small-cell carci-
noma (which encompasses the previous oat cell type and the
previous intermediate cell type) and combined small-cell car-
cinoma.299 Cells of the classic oat cell type are approximately
twice the size of lymphocytes and possess scanty cytoplasm, a
high nuclear/cytoplasmic ratio, nuclear hyperchromasia with
finely dispersed granular chromatin, and absent or inconspicu-
ous nucleoli (Fig. 13.71). Mitotic figures and necrosis are com-
mon. In areas of cell degeneration, the nuclei appears pyknotic
and exhibit a characteristic molding against each other. In bron-
chial biopsy specimens, crush artifact is frequently present and
is sometimes so pronounced that it renders the sample uninter-
pretable. Better-preserved areas reveal sheets of cells with occa-
sional perivascular pseudorosettes.298
The cells of tumors previously classified as the intermedi-
ate cell variant of small-cell carcinoma show a chromatin pat-
tern similar to that of the oat cell type but have larger nuclei
with somewhat more abundant cytoplasm (Fig. 13.72) and not
infrequently exhibit distinct nucleoli.346 In some cases, spindle-
shaped cells may predominate. Combined small-cell carcino-
mas include those cases which contain components of both
small-cell carcinoma and non-small-cell carcinoma (squamous,
large cell, or adenocarcinoma).299,347 By electron microscopy, a
few dense core neurosecretory granules may be demonstrated in
most cases of small-cell undifferentiated carcinoma, and some
may show ultrastructural evidence of squamous or glandular
differentiation.348 The latter findings, however, should not alter
the histologic diagnosis.
Most patients will small-cell carcinoma present with dissemi-
nated disease and consequently are not considered surgical can-
didates. Combination chemotherapy has brought about some
prolongation of life, but the overall 5-year survival is poor.346
Although some have suggested otherwise,349,350 it would appear
that tumors belonging to the older categories of oat cell carci-
noma and intermediate cell variant of small-cell carcinoma do
not differ significantly in behavior.351-353 The prognosis of com-
bined small-cell carcinoma is said to be similar to351 or worse
333
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