Based on a review article in ARPA. Approach to CUP with the help of IHC

1. Carcinomas of Unknown Primary Site
Kandalaft et al
(Arch Pathol Lab Med.doi: 10.5858/arpa.2015-0173-CP)

2.  Approximately 4% of all patients with cancer present
as CUPs
 IHC remains a gold standard at diagnosis
 2 classes of antibody markers that can help
- Antibodies to keratins
- Antibodies to organ restricted markers

3. Determine the cell line of differentiation
Determine the CK type or types of distribution
Determine co expression of vimentin
Determine expression of supplemental Ags (CEA, EMA,
PLAP)
Organ specific markers

4.  Low molecular weight
CK
- “simple” epithelium
- K8, K18
- Glandular epithelium of
GIT, hepatocytes
 High molecular weight
CK
- “complex” epithelium
- K5, K14, K17
- Stratified epithelium
- Ductal and basal cells
The subclassification of carcinomas by HMW and LMW
keratins has largely been superseded by subclassification
using antibodies to K7 and K20 which is a far more
powerful discriminator

5. Cancer of Unknown Primary
MD Anderson Cancer Center

6.  Urothelial tumors
 Ovarian mucinous adenocarcinoma
 Pancreatic adenocarcinoma
 Cholangiocarcinoma
 Gastric carcinoma

7.  Lung adenocarcinoma
 Breast carcinoma
 Thyroid carcinoma
 Salivary gland carcinoma
 Esophageal carcinoma
 Endometrial carcinoma
 Cervical carcinoma
 Cholangiocarcinoma
 Pancreatic carcinoma
 Gastric carcinoma
As a rule, gastric
adenocarcinoma
can show almost
any K7/K20
phenotype

8.  Colorectal carcinoma
 Merkel cell carcinoma (dot like pattern)

9.  Hepatocellular carcinoma
 Renal cell carcinoma
 Prostate carcinoma
 Squamous cell and small cell lung carcinoma
 Head and neck carcinoma

10.  Keratin 5 (and its pair 14) – marker of squamous,
transitional cell, myoepithelial and mesothelial
differentiation
 Keratin 17 – when expressed at high levels  good
marker for distinguishing between carcinomas of
pancreatobiliary origin from gastric carcinomas

11. CARCINOMAS
 Anaplastic thyroid
carcinoma
 Endometrial carcinoma
 Mesothelioma
 Metaplastic breast
carcinoma
 Myoepithelial carcinoma
 Renal cell carcinoma
 Sarcomatoid carcinoma
 Thyroid carcinomas
MESENCHYMAL
 Adamantinoma
 Chordoma
 DPSRCT
 Epithelioid angiosarcoma
 Epithelioid sarcoma
 Leiomyosarcoma
 Malignant rhabdoid tumor
 Synovial sarcoma

13. CYTOPLASMIC
- Level of expression and
fraction Function of
the state of
differentiation of the
tumor
NUCLEAR
- When positive  entire
tumor population
- Independent of the state
of differentiation

15.  2/3rd to 3/4th of primary breast
 Lower fraction of breast cancer in metastatic sites
 Primary in endometrium and ovary
 Papillary carcinoma thyroid
 Skin adnexal tumors
 10-20% of lung adenocarcinomas (focally)
 Rare in adenocarcinoms of GIT

16.  23A3 monoclonal antibody- 80% sensitivity
 Function of histological subtype
 Greatest in lobular (particularly those with signet ring
cells) and those with apocrine features
 Very small fraction of basal like carcinomas
 Salivary gland carcinomas and sweat gland carcinomas
 5-10% primary ovarian and endometrial carcinomas
 5-6% lung adenocarcinomas

17.  Sensitivity as a marker of breast cancer is LESS than
that of GCDFP 15 (50-70%)
 7% breast cancers are Mammaglobin A positive but
GCDFP 15 negative
 10% of ovarian and endometrial
 Skin adnexal and salivary gland tumors

18.  1 of 6 members of zinc finger transcription factor
family
 Very sensitive for breast and urothelial carcinoma
 Ductal 91%, lobular 100% diffuse and strong nuclear
staining
 UNLIKE previous two seen in 43% of triple negative
and 54% of metaplastic breast cancers
 Maintained in metastatic breast cancer (>90%)
 Skin adnexal, endometrial, pancreatic, salivary gland
carcinomas

20.  NKX2 family of DNA binding transcription factors
 Selectively expressed during embryogenesis in the
thyroid, diencephalon and respiratory epithelium
 Expressed in both neuroendocrine and non
neuroendocrine tumors of the lung

21.  Sensitivity of TTF-1 is greatest among adenocarcinomas
and nonmucinous bronchioloalveolar carcinomas
 Lowest in mucinous adenocarcinomas and squamous
cell carcinomas
 Appears to retain similar sensitivity in metastatic sites
 Small subset of ovarian, endometrial, and colorectal
carcinomas, although the extent of positivity is usually
focal, often in isolated clusters of cells

22.  TTF-1 expression cannot be considered specific for
high-grade neuroendocrine carcinomas of lung origin
 Variable subset of small cell (neuroendocrine)
carcinomas of the genitourinary and gynecologic
(GYN) tract
 Cell blocks of pleural fluids, which contain material
that has been either fixed in alcohol or is nonfixed
before creation of a formalin-fixed cell pellet, can
manifest a profound loss of TTF-1 antigenicity

23.  Aspartic protease that is crucial to the maturation of
surfactant B and present in the cytoplasm of type 2
pneumocytes and alveolar macrophages
 Very sensitive marker for detecting pulmonary
adenocarcinomas
 Subset of renal cell carcinomas
 Minority of endometrial adenocarcinomas and
papillary thyroid carcinomas
 Virtually all cases of clear cell carcinomas of the ovary

25.  Nuclear transcription factor  controlling the
proliferation and differentiation of intestinal epithelial
cells
 Virtually 100% of colorectal adenocarcinomas
 MSI  reduced or even absent expression
 CRC  uniform staining pattern
 Most adenocarcinomas of the stomach, pancreas, and
biliary tract  variegated or focal staining pattern

26.  ½ gastric (more in intestinal type) and 1/3 of
pancreatobiliary
 Ovarian mucinous carcinomas, bladder
adenocarcinomas, and sinonasal intestinal type
adenocarcinomas
 Limited subset of mucinous and nonmucinous
pulmonary adenocarcinomas (enteric subtype)

27.  Endocervical and endometrial  mucinous
differentiation
 ‘‘Squamous’’ morules of endometrioid hyperplasia and
carcinoma
 Germ cell tumors  intestinal differentiation
 GI neuroendocrine tumors, including those primary to
the intestine (eg, carcinoid tumors) and, to a variable
degree, the pancreas (islet cell tumors)

28.  Actin-binding protein, found preferentially in
microvilli
 Expression is largely (but not entirely) restricted to
glandular epithelium and corresponding
adenocarcinomas of the GI tract
 Expression is greatest and most reliably found in CRC
 Lower levels of expression are found in
adenocarcinomas primary to the pancreatobiliary tract
and stomach

29.  Scoring of the membranous or ‘‘brush border’’ signal is
most significant
 Cytoplasmic immunostaining can be seen in other
types of tumors, particularly neuroendocrine
carcinomas
 Can also be seen in adenocarcinomas of other sites
that display a GI-type histology and
immunophenotype
Although the individual sensitivities of CDX2 and
villin are each approximately 50%, their combined
sensitivity is in excess of 75%.

31.  Detects a liver (hepatocyte)-specific marker,
subsequently found to represent the enzyme
carbamoyl phosphate synthase
 Helps to distinguish metastatic carcinomas from
primary HCCs
 (1%–10%) subset of adenocarcinomas primary to the
lung, pancreas, stomach, ovaries, and adrenal cortex
 hepatoid morphology

32.  Enzyme involved in the urea cycle
 Appears to represent the most-sensitive (and, perhaps,
most-specific) marker of HCC to date
 Cytoplasmic, granular pattern
 High level of sensitivity even in the context of high-
grade HCC

33.  It is not expressed in ‘‘hepatoid’’ and other non-HCCs
(particularly carcinomas of the lung, stomach, and
kidney)
This is the marker of choice for
identifying HCC

34.  Oncofetal protein
 Proven useful in distinguishing HCC from
nonneoplastic hepatic lesions and hepatic adenomas
 In mets vs primary  high level of sensitivity and
specificity of arginase-1 to surpass the use of glypcian-3

36.  Nuclear transcription factor implicated in
tumorigenesis and in specifying normal urogenital
development
 Mesothelial cells, ovarian surface epithelium,
mesangial cells in the kidney, a subset of smooth
muscle cells, and granulocytic cells and precursors

37.  Marker of ovarian carcinomas in the context of
adenocarcinomas
 Mesothelioma distinguishing it from nonovarian
adenocarcinomas
 Desmoplastic small, round cell tumors
 Ovarian serous carcinomas, primary peritoneal
adenocarcinomas, and fallopian tube serous
carcinomas
 Very high sensitivity and specificity, both in excess of
90%.

38.  In a poorly differentiated ovarian carcinoma, nuclear
WT1 reactivity favors a serous neoplasm because
endometrioid, clear cell and mucinous carcinomas are
negative
 In the breast, WT1 is expressed in around 6% of the
cases, usually at low levels in pure mucinous (65%)
and mixed mucinous (33%) subtypes

39.  Subset of carcinomas arising within the female genital
tract, exhibit nuclear expression for ER
 In endometrial carcinomas of endometrioid type (type
1), ER antibodies are reactive
 Whereas in uterine serous and clear cell carcinomas
(type 2), they usually are not

40.  Can be part of a panel to differentiate endometrial
adenocarcinoma from endocervical adenocarcinoma
 No value in the distinction between a primary ovarian
adenocarcinoma (mainly including endometrioid and
serous carcinoma) and a metastasis from the breast or
from elsewhere within the female genital tract

41.  Transcription factor, which is critical to embryogenesis
of the thyroid gland, kidney, and mullerian system
 Nonciliated, mucosal cells of the fallopian tubes,
endocervix, endometrium, and simple ovarian
inclusion cysts BUT NOT on the surface of the
epithelial cells of the ovary
 90% to 100% of serous, endometrioid, clear cell, and
transitional cell ovarian carcinomas

42.  PAX8 is not expressed in mammary carcinomas,
including ductal and lobular types
 Because the ovary is a common site of
involvement for metastasis by breast carcinoma,
PAX8 can be a useful marker in the differential
diagnosis of ovarian and breast carcinomas

43.  Highly expressed in clear cell carcinomas of the ovary
 100% of tumors
 Clear cell carcinomas of the endometrium (82%)
 Few endometrial serous carcinomas (8%)
 NO endometrioid endometrial carcinoma

45.  Very high sensitivity of this marker, apparently
independent of Gleason score
 Overall sensitivity in the range of 95% and specificity
approaching 100%
 Expressed by a subset of breast cancers
 Also expressed focally in salivary gland and pancreatic
carcinomas

46.  Antibody to the prostatic tumor suppressor gene
NKX3.1
 Recently reported to be an extremely sensitive marker
for identifying metastatic prostatic adenocarcinoma
(positive in 99%)
 Level of sensitivity of NKX3.1 is maintained in high-
grade prostatic carcinomas

48.  More than 90% of urothelial carcinomas are positive
 Useful marker in distinguishing TCC from other non–
small cell carcinomas potentially in the differential
diagnosis, such as, prostatic adenocarcinoma
(especially high grade)

49.  Glycoprotein of the asymmetrical unit membrane,
which forms plaques on the apical surfaces of
urothelial umbrella cells
 First, specific, urothelial-restricted marker described
 High sensitivity in non invasive; low sensitivity in
invasive

51.  Critical to the embryogenesis of the kidney, is
identified in renal tubular epithelium and vas
deferens, but not glomeruli
 Most of the renal epithelial neoplasms
 Clear cell > Papillary > Chromophobe = Sarcomatoid
= Xp11 Translocation
 Not expressed in bladder TCC
 Subset of renal pelvic urothelial carcinomas

53.  Specific and sensitive markers of both primary and
metastatic carcinomas of the thyroid
 Excellent marker of papillary and follicular carcinomas
 Poor marker of anaplastic
 NOT a marker for medullary

54.  Even more-sensitive marker of thyroid carcinomas
than thyroglobulin
 Medullary also
 Anaplastic  negative

55.  Critical to the organogenesis of the thyroid gland and
is highly expressed in the thyroid follicular epithelium
 Papillary and follicular  100%
 Anaplastic  80%
 PAX8 is useful in discriminating between a TTF-1 +
lung adenocarcinoma and a TTF-1+ thyroid carcinoma
because PAX8 expression has not been identified in
primary lung adenocarcinomas

57.  Expressed in a restricted subset of healthy cells,
including ovarian granulosa cells, testicular Leydig
cells, and adrenal cortical epithelium
 Excellent marker for the identification of primary
adrenal cortical tumors and their distinction from
metastatic carcinomas to the adrenal gland
 Ovarian and testicular stromal tumors

58.  Alternative or supplementary marker of adrenal
cortical differentiation
 Sensitivity is comparable or even greater than that of
Inhibin

59.  100% specificity at discriminating these neoplasms
from other tumors with clear cell morphology, such as
renal cell carcinoma, ovarian clear cell carcinoma, and
chordomas
 High levels in sex cord-stromal tumors of the ovary
 Lower levels in testicular sex cord-stromal tumors

60.  Unique among epithelial tumors  very low level of
keratins
 Unique among nonneuroendocrine tumors 
synaptophysin

62.  Uniformly and strongly p63 and p40 positive  pure
SCC (lung and cervix)
 Thymomas can also be positive

63.  Uniform expression of p63 and p40, even in the setting
of poorly differentiated tumors, such as spindle cell,
bladder TCC

64.  Carcinomas demonstrating myoepithelial
differentiation (eg, adenoid cystic and other salivary
gland carcinomas)
 Carcinomas demonstrating trophoblastic
differentiation.

66.  73 years old man
 Long term smoker
 Needle biopsy of single left lower lobe lung nodule

67. CK 20
CDX 2 TTF 1

68. Metastatic adenocarcinoma from
rectosigmoid

70.  63 years old male
 Cervical lymph node needle biopsy
 No known primary
 Suspicious for lymphoma

71. CK 7
PSA VILLIN

72. Metastatic prostatic adenocarcinoma

74.  55 years old woman
 Right axillary lymph node biopsy
 Ill defined density seen on mammogram
 PET positive uptake in right parotid gland

75. GCDFP-15
GATA 3 HER 2

76. Metastatic ductal carcinoma from breast

78.  73 years old woman
 Needle biopsy of retroperitoneal lymph node
 History of hysterectomy for unknown reasons many
years back
 Retroperitoneal lymphadenopathy, possible splenic
metastasis
 Left pelvic sidewall mass on CT scan - ?residual ovary

79. ER
WT 1 PAX8

80. Metastatic high grade serous carcinoma
of ovary

82.  58 years old man
 Needle biopsy of mediastinal lymph node
 Recent diagnosis of prostate adenocarcinoma (Gleason
score 4, “hypernephroid”)
 Nephrectomy 5 years ago for sarcomatoid renal cell
carcinoma
 Remote history of melanoma
 Presented with mediastinal and lung masses

83. CK
PSA PAX 8

84. PAX 8 + male  thyroid and renal
TTF negative
Metastatic renal cell carcinoma