190
UNIT 3
Organ Systems
Figure 10-9A.
Appendix, MALT.
H&E,
3
18
The
appendix
and
Peyer patches
in the ileum of the digestive system
are
GALT
. The
appendix
is a small, blind tube that extends from
the cecum in the lower right quadrant of the abdomen. It contains
large numbers of
lymphatic nodules
in its lamina propria. Most
of the nodules are secondary nodules with germinal centers. The
secondary nodules often penetrate into the submucosa.
Lymphatic
nodules
A
CLINICAL CORRELATIONS
Figure 10-9B.
Diffuse Large B-Cell Lymphoma.
H&E,
3
1,000
Diffuse large B-cell lymphoma (DLBCL)
is the most
common type of
non-Hodgkin lymphoma
(25% of all
lymphomas), characterized by a fast-growing and often
symptomatic mass at a nodal or extranodal site. The
most common extranodal site is the gastrointestinal
tract, but other sites include skin, soft tissue,
Waldeyer
ring
, lung, spleen, and kidneys. Patients may experi-
ence fever, weight loss, and drenching night sweats.
Histologically, tumor cells are large with
large nuclei
,
open chromatin
, and
prominent nucleoli
. The tumor
grows in a diffuse pattern. Treatment for DLBCL
includes intensive combination chemotherapy with
possible radiotherapy to the involved tumor site.
Figure 10-9C.
Lymph Node, HIV Infection.
H&E,
3
40
HIV infection
is associated with a progressive decline
in helper T lymphocytes, resulting in immunosuppres-
sion (Fig. 10-5B). Patients with acute HIV infection
may experience fever,
lymphadenopathy
,
pharyngitis
,
rash
, and
myalgia
. The chronic phase of HIV infection
may last from months to years with patients exhibiting
few symptoms. During the ±
nal crisis phase, patients
are at an increased risk of opportunistic infections and
neoplasms.
Lymph nodes
in the early stage of HIV
infection show marked follicular
lymphoid hyperplasia
with enlarged, irregularly shaped follicles (lymphatic
nodules) and increased numbers of
macrophages
in
the
germinal center
. The enlarged lymph nodes may be
found ±
rst in the upper body, then around the lungs,
and ±
nally around the bowel. Patients with compro-
mised immunity are highly likely to be infected by
bacteria and other microbes. Anti-HIV drugs include
four major classes:
Reverse transcriptase inhibitors
,
protease inhibitors
,
entry
and
fusion inhibitors
, and
integrase inhibitors
.
Lymphoma cells
with large nucleolus
Large irregular
lymphoma cells
B
Enlarged and
irregular-shaped
lymphatic nodules
Lymphatic
Lymphatic
nodules
nodules
Lymphatic
nodules
C
Appendicitis
is a common disease, which may be triggered by
bacterial and viral infections resulting in hyperplasia of lymphatic
nodules and obstruction of the lumen of the appendix. Patients
may experience abdominal pain, which most likely will be local-
ized at the
McBurney point
(one third of the distance between the
anterior superior iliac spine and the umbilicus on the right side) as
the disease progresses. Fever, nausea, and vomiting are the com-
mon symptoms. Emergency
appendectomy
is the ± rst treatment
choice for most cases.
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