2. Carcinoma of unknown primary
Definition: histologically confirmed
metastatic carcinoma for which
primary site cannot be identified after
standard diagnostic approach:
• Detailed history and physical examination
• Blood counts and biochemical analysis
• Urinalysis and stool occult blood test
• CT of thorax, abdomen, and pelvis
• Histologic review including IHC
3. Carcinoma of unknown primary
• Account for 2-5% of malignancies
diagnosed in the US
• 7th or 8th most frequent cancer
• 4th or 5th most common cause of
cancer death in both sexes
• 31,000 new cases in the US in 2012 –
down from 45,000 new cases in 1995
• Improved radiologic imaging
• Increasingly specific IHC markers
4. Organ Incidence
Pancreas 20-25%
Lung 15-20%
Colon/rectum 5-10%
Liver/biliary 5-10%
Stomach 5%
Kidney 5%
Ovary <5%
Prostate <5%
Breast 2%
Other 1%
Origin of primary tumors (autopsy)
5. Histology Frequency
Well or moderately differentiated
adenocarcinoma
60%
Poorly differentiated
adenocarcinoma
or undifferentiated carcinoma
30%
Squamous cell carcinoma 5%
Undifferentiated malignant
neoplasm
5%
Histologic groups of carcinoma of unknown primary
6. Keratin family members in
carcinomas
• Low-molecular-weight keratins
(CK8, CK18, CAM5.2)
– Glandular epithelium, hepatocytes
• High-molecular-weight keratins
(CK5, CK14, 34βE12)
– Squamous epithelium, urothelium,
basal cells
7. Keratin family members in
carcinomas: CK7 and CK20
• CK7 wide distribution in epithelial
cells
• CK20 restricted to lower GI tract
epithelium, umbrella cells of the
urinary bladder, Merkel cells
14. Napsin A
• Warning: napsin A is also positive in
most papillary renal cell carcinomas
15. IHC for lineage/site specification:
nuclear transcription factors
• Insights gained from developmental and
cell biology research
• Transcription factors involved in patterning
of organ systems, lineage commitment
• Some are highly specific for particular cell
type or visceral organ
• Others show expression limited to several
tissue types
• Very helpful in determining primary site for
CUP
16. 1.In molecular biology, a transcription factor is a protein
that controls the rate of transcription of genetic
information from DNA to messenger RNA, by binding to a
specific DNA sequence. Their function is to regulate - turn
on and off - genes in order to make sure that they are
expressed in the right cell at the right time and in the right
amount throughout the life of the cell and the organism.
Groups of TF's function in a coordinated fashion to direct
cell division, cell growth, and cell death throughout life;
cell migration and organization during embryonic
development; and intermittently in response to signals
from outside the cell, such as a hormone. There are up to
2600 TFs in the human genome
18. TTF1 (NKX2-1) (thyroid TF)
• Lineage-specific transcription factor long
history of use in diagnostic IHC
• Originally named for role in activating
transcription from thyroglobulin promoter
• Expressed in normal and neoplastic thyroid
follicular cells
• Most widely used application: ascribing
lung origin to primary and metastatic
adenocarcinomas (and supporting
adenocarcinoma over squamous cell
carcinoma in poorly differentiated NSCLCA)(NON SMALL CELL LUNG CANCER)
19.
20.
21. Primary site Positive cases
Pulmonary
(adenocarcinoma)
70-90%
Pulmonary (squamous
cell carcinoma)
<10%
Thyroid (all types) 80-100%
Cholangiocarcinoma
(extrahepatic)
5-25%*
Endometrial 5-20%*
Ovarian 5-30%*
Expression of TTF1 in carcinomas I
*These cases usually show expression in only a small fraction of
tumor cells
22. Primary site Positive cases
Gastric/esophageal <10%
Cervical <5%
Pancreatic <5%
Breast <5%
Urothelial <5%
Colorectal <5%
Hepatocellular <5%
Salivary gland (adenoid cystic) 30-50%
Salivary gland (other) <5%
Adrenal cortical <5%
Expression of TTF1 in carcinomas II
23. WT1
• Wilms tumor 1
• Transcription factor plays diverse roles
in cancer depending upon tumor type
and biological context
• Expressed in malignant mesothelioma,
serous carcinoma
• Positive in nearly all serous carcinomas
of the ovary; uncommon in serous
carcinomas of the endometrium
(variable results in different studies)
24.
25. CDX2
• Caudal-type homeobox transcription
factor involved in intestinal
differentiation
• Nuclear expression in >90% colorectal
adenocarcinomas
• Somewhat lower sensitivity in high
grade and MSI-H carcinomas
• Widely used to support colorectal origin
• No significant loss of sensitivity in the
metastatic setting
26.
27. CDX2
• Also expressed in carcinomas from other
gastrointestinal primary sites associated
with intestinal differentiation
– Esophagus and stomach
– Pancreas and biliary tree
• Often more heterogeneous staining in
tumors from these other sites
• Particularly helpful in differential diagnosis
between primary (poorly cohesive) gastric
carcinoma and metastatic breast
carcinoma
28. GATA3
• Transcription factor originally
recognized for role in T-cell function
• Clinically useful as marker for breast or
urothelial origin
• Positive in >80% of breast and urothelial
carcinomas
• No significant loss of sensitivity in the
metastatic setting
• More recent large surveys revealed
expression in wide range of tumor types
29.
30.
31. Positive Negative
Metastatic lobular breast
carcinoma
Gastric signet-ring-cell carcinoma
Metastatic ductal breast
carcinoma
Lung/GI/ovarian adenocarcinoma
Urothelial carcinoma Prostatic adenocarcinoma
Squamous cell carcinoma of skin Squamous cell carcinoma of lung
Malignant mesothelioma Lung adenocarcinoma
Paraganglioma Other neuroendocrine tumors
Choriocarcinoma, yolk sac tumor Embryonal carcinoma, seminoma
Potential value of GATA3 in
differential diagnosis
32. NKX3-1
• Homeobox transcription factor,
androgendependent
• Expression limited to prostate
• Usually more diffusely positive than
conventional cytoplasmic markers
• Helpful to distinguish high grade prostatic
adenocarcinoma from urothelial carcinoma
• Helpful to suggest prostatic origin in
metastatic carcinoma
33.
34. SATB2
• More recently described transcription
factor expressed in colorectal/appendiceal
epithelium
• Similarly high sensitivity and likely higher
specificity than CDX2
• Positive in 80-90% of primary and
metastatic colorectal adenocarcinomas
• Higher sensitivity than CDX2 for medullary
carcinomas
• Unlike CDX2, SATB2 rarely expressed in
gastroesophageal and pancreaticobiliary
adenocarcinomas
35.
36. PAX8
• One of the most widely used lineagespecific
transcription factors in IHC
approach to CUP
• Highly sensitive for carcinomas
originating in ovary, kidney, thyroid
• >90% serous, endometrioid, and clear
cell ovarian carcinomas positive for
PAX8
• Much lower rate of expression in
ovarian mucinous adenocarcinomas
• PAX2 largely supplanted by PAX8
37.
38.
39. SF1
• Steroidogenic factor 1 (NR5A1)
• Recently investigated transcription
factor
• Highly sensitive marker for sex cordstromal tumor
• Highly sensitive marker for adrenal
cortical carcinoma
• Particularly useful in distinguishing
primary adrenal cortical carcinoma
from metastatic renal cell carcinoma
40.
41. Hepatocellular carcinoma
• Alpha fetoprotein (AFP)
– Low sensitivity
• Polyclonal carcinoembryonic antigen (CEA)
– Bile canalicular pattern
• Carbamoyl-phosphate synthase 1 (CPS1) =
Hep-Par 1 antibody
– Urea cycle enzyme
– Also expressed in 5-10% of adenocarcinomas
of diverse sites
• Arginase 1 (ARG1)
– Urea cycle enzyme
– Appears to be most sensitive and specific
