212
UNIT 3
Organ Systems
CLINICAL CORRELATION
Figure 11-10C.
Small Cell Neuroendocrine Carcinoma
.
H&E,
3
213
Small cell neuroendocrine carcinoma
is a highly malignant
lung tumor characterized by its origin from the epithelium of
the central airways, rapid growth, inF ltration, gradual obstruc-
tion of the airways, and early metastases. It is associated
with
genetic mutations
,
air pollution
,
and
cigarette smoking
.
Patients will likely present with large hilar lymph nodes with
prominent mediastinal adenopathy in computed tomography
or other radioimagings. Symptoms include weight loss, cough,
chest pain, and dyspnea. The liver, adrenals, bones, bone
marrow, and brain are the common sites of metastasis. The
tumor cells
are round, small, and spindle shaped with spare
cytoplasm, ill-deF ned cell borders, prominent nuclear mold-
ing, and F nely dispersed chromatin without distinct nucleoli.
The tumor cells are about twice the size of lymphocytes and
have characteristic “blue” cell features. Small cell carcinoma
is initially very sensitive to chemotherapy and radiotherapy,
but loses its sensitivity within months. Treatment also includes
surgery if the cancer is discovered at an early stage.
Figure 11-10A.
A small tertiary bronchus and bronchioles,
lung.
H&E,
3
25
A
small tertiary bronchus
and several different sizes of
bronchioles
are shown here. Small tertiary bronchi have much
smaller diameters than large tertiary bronchi (±ig. 11-8C). Its
hyaline cartilage is reduced to a few plates and the epithelial
lining has decreased numbers of goblet cells and glands in the
submucosal layer. These submucosal glands gradually disappear
as the airways become smaller. Small tertiary bronchi give rise
to smaller airways called
bronchioles
, which, because of the ran-
dom branching pattern of the airway, appear at various places
in the section. The glands and the cartilage plates of the bron-
chioles have completely disappeared at this level. Bronchioles
continue to branch and decrease in size and give rise to
terminal
bronchioles
(±ig. 11-11B,C).
Small tertiary
Small tertiary
bronchus
bronchus
Bronchiole
Bronchiole
Bronchiole
Bronchiole
Bronchiole
Bronchiole
Cartilage plates
Cartilage plates
Small tertiary
bronchus
Bronchiole
Bronchiole
Bronchiole
Cartilage plates
A
B
Bronchiole
Bronchiole
Lymph
Lymph
nodule
nodule
Smooth
Smooth
muscle
muscle
Smooth
Smooth
muscle
muscle
Bronchiole
Lymph
nodule
Adventitial layer
of the bronchiole
Smooth
muscle
Smooth
muscle
Figure 11-10B.
Bronchioles, lung.
H&E,
3
71; inset
3
612
The
bronchioles
are lined by ciliated columnar or cuboidal
epithelium with decreased numbers of
goblet cells
and increased
numbers of
Clara cells
.
Goblets cells
occasionally can be found
in larger bronchioles.
Clara cells
are present in small bronchi-
oles, and their numbers are greatly increased in
terminal bron-
chioles
(±ig.11-11A). There are many elastic F
bers in the lamina
propria, which are not easy to see here with H&E stain. A layer
of
smooth muscle
on the bronchiole wall is shown in the
inset
.
The
connective tissue
(
adventitial
)
layer
is attached to the sur-
rounding alveoli.
Lymph nodules
or diffuse lymphocytes are
occasionally found in the connective tissue layer. The epithelium
lining the bronchioles changes from columnar to cuboidal cells.
Each bronchiole gives rise to several terminal bronchioles as it
branches distally in the lung.
C
Tumor cells
previous page 227 Dongmei Cui -  Atlas of Histology with Functional and Clinical Correlations 2011 read online next page 229 Dongmei Cui -  Atlas of Histology with Functional and Clinical Correlations 2011 read online Home Toggle text on/off