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A 32-year-old man presented with intermittent abdominal
pain for 2 weeks. He had otherwise been well until
May 7, 2007 when he devloped sudden onset of progressive abdominal
pain. The symptoms improved temporarily after taking
medications from local clinics, but they recurred on the
next day. He was on regular diet as usual over the following one
week, though he still complained of intermittent postprandial abdominal
fullness. He noted that the stools became liquid
or semi-liquid in consistency, occasionally covered with
blood streaks. On May 17, 2007, sudden onset of lower abdominal
pain developed again. The abdominal pain which accompanied
by vomiting made him unable to walk this time. Therefore,
he was admitted to the hospital on May 17, 2007. He smoked
1.5 packs of cigarettes and with habitual drinking. He was
single, and his father, two elder brothers and one elder sister
also had colon cancer.
On examination, he appeared
acutely ill, with regular pulse of 97 beats per minute, a
respirations 22 breaths per minute, blood pressure 180/70
mmHg, and temperature 37.8 ℃. His height was 168 cm and weight
56 Kg. The conjunctiva was pink. The sclera was anicteric. The
neck was supple without jugular vein engorgement. The thyroid
was not enlarged and there was no palpable lymph node. The
chest expansion was symmetric without abnormal or adventitious
sounds. Cardiovascular examination showed regular heart beat
without murmurs. The abdomen was soft but one tender point was
noted at the right lower quadrant with mild rebound
tenderness. The bowel sound appeared hypoactive and both liver
and spleen was impalpable. There were no skin rashes or
lentiginous rashes on the face, and there was no leg edema.
< Laboratory Data
>
Complete blood count and differential count
| |
WBC |
Hb |
Hct |
Plt |
MCV |
MCHC |
|
|
K/mcL |
mg/dL |
% |
K/mcL |
fL/mcL |
gm/dL |
|
5/17 |
17.72 |
11.4 |
35.6 |
624 |
87.9 |
32 |
|
|
Seg |
Band |
Eos |
Lym |
Mono |
Baso |
|
|
% |
% |
% |
% |
% |
% |
|
5/17 |
87.6 |
0 |
1.7 |
6.7 |
3.6 |
0.2 |
Biochemistry
|
|
BUN |
Cr |
Amylase |
Lipase |
Na |
K |
Ca |
AST |
ALT |
|
|
mg/dL |
mg/dl |
U/L |
U/L |
mEq/L |
mEq/L |
mg/dL |
U/L |
U/L |
|
5/17 |
8.8 |
0.8 |
63 |
18 |
137 |
4.6 |
2.04 |
65 |
15 |
|
|
T-bil |
ALP |
rGT |
LDH |
CRP |
|
|
mg/dl |
U/L |
U/L |
U/L |
mg/dl |
|
5/21 |
0.32 |
104 |
16 |
416 |
2.7 |
Stool
Occult blood: 2+,
<
Course and Treatment >
On admission,
intra-abdominal infection was suspected. KUB (Figure-1b)
showed focal ileus at the cecum level. Abdominal sonography
(Figure
2) revealed ascites with a heterogeneous mass at the left
lower abdomen. Cefmetazole was given under the suspicion of
ruptured appendicitis or a cecal tumor. Abdominal computed
tomography (Figure 3)
showed a cecal and rectal mass with lumen obstruction.
Colonoscopy disclosed multiple colon polyps (Figure 4a,
b ). However, the scope was unable to advance further
when reaching the rectal tumor. Biopsy was done over the rectal tumor
and colon polyps which revealed tubular adenoma with focal
low-grade to high-grade intraepithelial neoplasia (Figure 5 a,
b, c).
According to
the finding of multiple polyps and a family history of colon
cancer, familial adenomatous polyposis (FAP) was diagnosed.
Thyroid sonography (Figure
6), computed tomography of the head (Figure 7)
and enteroscopy (Figure 4c,
d
) for detecting
extra-colonic manifestations of FAP were performed and show gastric polyps,
with normal results of the thyroid and brain.
For familial
adenomatous polyposis, he underwent subtotal colectomy and
ileostomy on May 25, 2007 smoothly. Thousands of colon polyps
and rectal and cecal mass were noted intraoperatively (Figure
8), and the pathology (Figure
5d
) revealed malignancy. The postoperative
course was smooth, and he was discharged on June 3, 2007 with
stable condition.
< Discussion
>
Familial adenomatous
polyposis最主要的臨床特徵，就是在大腸直腸中會產生數百甚至數千個以上的腺瘤性瘜肉。此疾病是一種自體顯性遺傳，但少部分的病患沒有家族史，而是藉由本身基因突變而導致。其最主要的基因變異是在於第五對染色體上5q21-q22
(APC gene)出現變化。喪失該部分正常基因會導致腫瘤抑制基因（tumor suppressor
gene）功能喪失，以致於腫瘤的增生失去抑制。
診斷上依賴三大準則： 1、大腸瘜肉超過100個；
2、家族成員有polyposis coli病史；3、染色體 5q21-q22 APC 異常。
此疾病主要分成三大變異型：
(1) .Gardner's
syndrome
常見的大腸外的表現為軟組織或骨頭腫瘤、視網膜色素細胞增生、硬纖維瘤
(Desmoid tumor與壺腹周圍癌症 (Ampullary cancer)等。
(2).Turcot's syndrome
常見的大腸外的表現為中樞神經腫瘤
(3).Attenuated familial adenomatous polyposis
少數病患的瘜肉數不到100顆，則歸於此亞型。
雖然Familial adenomatous
polyposis所佔比例不到所有大腸直腸癌的1%，但是患者於十五歲或青春期過後便開始逐漸出現瘜肉，到三十五歲前則幾乎全部會表現出來，而病患年屆35-40歲時百分之百會癌化成為惡性腫瘤，因此疾病的診斷、治療以及家族成員的篩選顯的更為重要。
少數認為使用NSAID，如sulindac，或COX-II
抑制劑，如celecoxib可以減少瘜肉數量，但目前仍認為大腸切除為最主要的治療。
因為瘜肉分佈出現直腸至盲腸等區域，因此篩檢部分目前認為直腸鏡(proctosigmoidscopy)
即可達到良好效果而不需要做到昂貴的整段大腸內視鏡檢查(Colonoscopy)。目前建議有家族病史的人一直到50歲止前，需要接受每年一次的內視鏡篩檢。單獨利用大便潛血反應作為篩檢工具則為不恰當。至於APC基因篩檢，目前運用於臨床，這樣的檢驗可於瘜肉未產生前便診斷出疾病。
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Case Discussion
繼續教育考題